The Model Yacht: Volume 3, Number 2 – Fall 1999

LINCOLN MEMORIAL POOL, WASHINGTON, D.C. NEWSLETTER OF THE U.S. VINTAGE MODEL YACHT GROUP VOLUME THREE, NUMBER TWO FALL 1999 NEWSLETTER OF THE U.S. VINTAGE MODEL YACHT GROUP VOLUME THREE, NUMBER TWO FALL 1999 Editor’s Welcome We are late with this issue for several reasons. Our national events did not end this year until September and we wanted to cover them all in a single issue. Then there was that perpetual interference called “a job,” which occupied more time than it should have. Finally, we had the effrontery to take a break from “paper yachting” to build and sail a free-sailing M boat. As always, we ask that you check your mailing label to see when we think your subscription runs out. If it says “32,” for “Volume 3 Number 2,” then we think this is your last issue and have enclosed a SASE for your renewal, three issues for $15.00. If you think we got it wrong, drop us a note and we’ll fix it. We’ve just moved the subscription list to a high-tech format (a Rolodex) which should make it easier to keep track of everybody. We have received several indications that some copies of Volume 3, Number 1 were lost in the mail. If this happened to you, contact us in any of the ways listed on the masthead (phone, email, U.S. Mail) and we’ll get a copy out to you. Besides the descriptions of our events, this issue contains two technical articles of note. One describes the previously undocumented work of Nathanael Herreshoff on vane gears. The other article is a 1928 reprint on design. We hope you enjoy them. Earl Boebert Ebbs and Flows The President’s Message Vintage Membership Our annual $15 fee covers three issues of the VMYG newsletter – “The Model Yacht”, and access to technical assistance and vintage model plans. A VMYG lifetime membership is $100. Our “how to” book/video package on plank-on-frame model construction is available to members but not included with the annual fee. To subscribe to our newsletter and services, send a check (payable to US VMYG) or cash for $15 (or $100) to: John Snow, c/o US VMYG, 78 East Orchard St., Marblehead, MA 01945. For inquiries on our activities, either call me @ 781-631-4203 or visit the VMYG Web Page at http:// www.swcp.com/usvmyg R/C “Vintage M” (VM) Group There are two VM divisions: 1945 and prior designs, “Traditional M’s, and post-1945 through 1970 designs, “High Flyer M’s. For rating rules or VM registration, contact Charlie Roden, the VM Coordinator, at 19 Oak Glen Ln., Colts Neck, NJ 07722 and 732-4627483. Email: c.roden-5@worldnet.att.net A report on the September VM regatta, which included a static judging event, appears elsewhere in this issue. Traditional Sailing Craft/Scale Models Group Schooner model rules are available through our Traditional Coordinator Harry Mote at 18 Woodmansee Blvd, Barnegat, NJ 08005 and 609-660-0100. Email: stryker@cyber- Page 1 comm.net This group held its annual regatta, which combines sailing and static judging, in conjunction with the VM regatta in September. Proposed R/C American Classic “50/800” (C50) Group The VMYG supports activities for “M 50/ 800” model yachts from early AMYA designs: 1971 to 1991 “M” boats with conventional sail rigs having non-kevlar hull material. The C50 Group Coordinator is Dennis Lindsey at 515 N. Lyall Ave, West Covina, CA 91790 and 626-966-9538. Email: lindseyd@flash.net Dennis has a listing of older AMYA M designs and C50 rating rules. “A” Class Invitational Regatta The VMYG supports AMYA “A” Class activities to help preserve the “A” as viable class/ design entity, in light of the early international “A” competitions popularizing the sport. Only a single US “A” regatta was held in 1999. It was hosted by the Mill Pond MYC which still schedules monthly “A” races. If interested, contact Commodore Charlie Blume at PO Box 227, Port Washington, NY 11050 or 516-883-0207. A report on their August invitational “A” race is elsewhere in this issue. In the event the “A” Class Secretary may step down, the VMYG will continue to coordinate with the AMYA in their efforts to regenerate interest in the “A”. WoodenBoat Show Report Several members actively supported the VMYG booth and R/C sailing demos at 1999 WB Show at the Chesapeake Bay Maritime Museum in St. Michaels, MD. These included Alan & Nan Suydam, Harry & Alice Mote, Charlie & Dot Roden, Biff Martin, Don Miller, Tom Younger and The Marbleheaders of Spring Lake, NJ Club members. We had several neat examples of VM, schooner and skipjack models on display and sailing daily. The crowds at our booth seemed as large as last year, with a total three-day show attendance of 10,000. Vintage Etcetera The VMYG participated in three other summer events: SFMYC “VM” Free-Sail Regatta at Spreckles Lake, 17th Annual Boston Antique & Classic Boat Festival and “Family Day” at IYRS in Newport, RI. There is a report in this issue on the SFMYC event run by Jeff Stobbe, which Earl Boebert and Ron Thornhill attended. Locally, Jim Dolan, Steve Denis and myself manned a VMYG booth at the IYRS event, with Jim, John Storrow and myself doing likewise at the Boston festival, along with model sailing. In addition, Thom McLaughlin is to be commended for teaching a highly successful model building course (36-inch, hard chine sailing design) at the Wooden Boat School this August. Given the interest generated and that there were sixty people on this year’s waiting list, it is likely that another course(s) will be taught in 2000 by Thom and possibly other VMYG members. The VMYG and the AMYA have made a formal proposal to the Mystic Seaport Museum for a 2000 “J” Class “Challenge Cup” Regatta involving the original “J” designs of 1930s America’s Cup fame in R/C models. The objective, like our “A” support, is to help regain visibility for an AMYA class with vintage design roots. Vintage Films One final plea for old film of early model racing scenes involving free-sailed models, both skiff and pond. Our goal for 2000 is a historical video documenting this aspect of the sport. Anyone having such film and willing to loan it to the VMYG should contact Earl Boebert @ 505-823-1046 or via email at: boebert@swcp.com Confirmed 2000 Vintage Events WoodenBoat Show – June 23-25 Mystic Seaport Museum, Mystic, CT; VM/Traditional Sailing Craft model displays/demonstrations, plus exhibits of full-size wooden sail/power boats and accessories/maritime items by trades people. VMYG Contact – John Snow 781-6314203 National Vintage Regatta – August 11-13 Redd’s Pond, Marblehead, MA; R/C VM & Traditional Sailing Craft model regattas/displays. Friday optional for free-sail VM racing at Redd’s Pond. Model yachting exhibit at Marblehead Historical Society April – October. Marblehead MYC Contact – John Snow 781631-4203 International Yacht Restoration School “Family Day” August 20 IYRS, Newport, RI; VMYG model display; IYRS exhibits/open house, harbor excursions, children’s activities. VMYG Contact – John Snow 781-631-4203 Page 2 John Snow Nathanael Herreshoff’s Vane Gears Nathanael Herreshoff Nathanael Green Herreshoff (1848-1938), known to all as “Captain Nat,” was perhaps one of the most creative individuals ever to concern himself with watercraft. His innovations covered every aspect of boating, from hull design to powerplants to fittings. He had a strong aesthetic sense, so that even the smallest details of his designs were, themselves, works of art. He designed hulls in three dimensions by carving half-hulls and then taking measurements off of them for the builders. These models, and those made by later Herreshoffs, are the principal displays in the Model Room of the Herreshoff Museum in Bristol, Rhode Island and are well known in the world of yachting. neutral. The vane arm, 5, is attached through a sliding linkage to the tiller arm, 6, which is rigidly attached to the rudder. If the boat changes course relative to the wind, the wind strikes the feather, swinging it and the vane base. This in turn moves the tiller arm and the rudder, and a course correction is made. The vane gear was invented by Captain Nat in 1875. It was installed on a model catamaran, which can be viewed today in the Museum. The vane feather was a real bird feather (probably turkey) and rode atop a tripod mast. A series of wooden shafts, arms, and bellcranks transmitted the movement of the feather to the rudder. What are not so well known are the sailing models in the museum. The oldest of these that we can date is a catboat of about 18” LOA with the following notation on its deck in Captain Nat’s own hand: Made by NGH for himself, 1861-1862. Passed: Francis H 1865 Julian H 1866 Bertie C About 1880 L. Francis 1903 Returned N G Herreshoff 1936 This is the oldest American sailing model we know about whose age has been documented. There are many other sailing models in the museum, each of which deserves an article of its own. This article will concentrate on one aspect of one boat: the vane gear on a large sailing model named “Robie,” which was built by Captain Nat over the winter of 1929-30 when he had retired to Coconut Grove, Florida for his health. This large boat, and her slightly older sister “Trillium,” also in the Museum, are equipped with vane steering gears of a previously undocumented design. Vane Gear The simple form of a model vane gear is shown in the illustration. The feather, 1, is set at the desired angle on the base 4; the angle is determined by the desired course relative to the wind; the feather is set so that when it is held by the wind the rudder is The patent diagram by Iversen that prompted Captain Nat’s letter to The Model Yachtsman. The working of the vane is described in the text. Page 3 Subsequently, there were a few isolated instances of its re-invention in one form or another until 1932, when an article in the British journal The Model Yachtsman described a workable design. The designer, one Iversen, thought he had a patentable device. He was disabused of this by the following letter from Captain Nat, which appeared in the December 1932 issue of The Model Yachtsman: Dear Sirs: I have been much interested in reading the article in your October number entitled “A Novel Automatic Steering Gear for Model Yachts,” as I have had quite an experience with devises for steering sailing models directly by angle of wind movement to the course desired for the model, and I consider it the best principle, when the details are properly worked out. Way back in 1875 when I was working on double-hulled sailing craft — the details of which I had patents and I also constructed many — I made a model of the contrivance about 33 inches long. This I sailed, but could not keep it on a course until I added a wind vane that controlled the rudder, and it did the trick perfectly. Due to busy days, I did no more with the idea until a few years ago, when I took up model making just to give exercise without having to stand much over on fatigue. I built four models to which I applied the windvane steerer, and when I tried each proved successful. I carried out the details somewhat different in each case, but all having the same principle of connecting the rudder to the wind-vane so they turn reverse directions. In one case a pin on the arm on lower end of vane shaft worked in a forked tiller turned on the rudder shaft, exactly as shown in the illustration on page 148. However, the details of the vane shaft and adjusting mechanism are quite different. The arrangement as shown in your paper is crude, as it is not designed to eliminate friction and the inertia of moving parts. In mine the wind vane iscounter balanced so that careering or rolling of the model will have no effect. The entire weight of vane and gear bears on a fine pivot point, so the slightest air will swing the vane. Also, the rudder blade is of the same specific gravity as water, so it is not effected by careering and turns very easily. I tried an elastic centering device and found it was not needed, and I also arranged a disc on the vane shaft with a circle of pin holes that a pin on the Nathanael Herreshoff’s vane gear, as installed on “Robie.”. Page 4 F1 F3 devised by Ted Houk in the U.S. in 1940. Houk went on to invent the “break back” mechanism, after which all advances were essentially in the details. Fore An Engineering Puzzle F2 T2 L1 L2 F4 L3 T1 T3 Perspective Layout of the Herreshoff Vane Gear vane dropped into to hold the vane at desired angle and gave that up in favour of a friction arrangement on disc that is adjustable by screws to give sufficient friction to control the rudder, but can be pushed round to any angle in an instant without breaking anything. I sent a drawing of this arrangement to a New York yachtsman and model enthusiast who asked for it, with the declaration that I had not patents, and gave it freely to the public. Unfortunately, the device was not carried out correctly and had considerable friction and, therefore, failed. The principle certainly is not patentable, but of course some special details may be. Yours Truly, Nathanael G. Herreshoff Besides establishing precedent, this letter provided several hints that helped in deducting the operation of “Robie”’s vane gear. Subsequent developments included the incorporation of a “self-tacking” ability. This feature permitted a boat to tack in the middle of a pond. A primitive self-tacking mechanism was described by Lt. Col. F. Moffitt of Great Britain in 1936. A similar geometry was We had several pictures of the Herreshoff vane gears taken from a considerable distance, but were still somewhat taken aback when we saw the actual device close up. It was clear that this was a much more complicated and advanced arrangement than we had expected. Since no notes or letters (except the one quoted above) about Captain Nat’s experiments are known to have survived, we were faced with a reverse engineering problem. This was compounded by the age and importance of the device in the Museum, which precluded disassembly or anything other than the most gentle movement of parts. Despite this, we feel we have a solution which will withstand scrutiny. A guiding principle in our analysis was that this device was constructed by a man who was an elegant designer and a fastidious craftsman; it can be safely assumed that no part on the vane is put there by accident. Dimensions “Robie” is slightly smaller than an “A” boat of her era: 68” LOA, 47” LWL, 12” beam and carrying about 1500 sq. in. of sail. She is gunter rigged, and equipped with wishbone booms, which Captain Nat favored for models. We were not able to weigh her, but we estimate she displaces around 30 pounds. The vane gear is considerably smaller than those evolved for competition, being only about 3” high. “Robie” has a high aspect rudder of 11 sq. in. area, balanced by a tab of about 1.5 sq. in. ahead of the pivot. The vane feather has about 22 sq. in. of area. This 2/1 ratio contrasts sharply with the recommended 5/1 to 9/1 ratios of competition vanes. Part of the difference can be explained by the balanced rudder; other comparisons will have to wait until someone takes the lines off “Robie” and builds and sails a replica. Operation of the Herreshoff Vane As shown in the perspective view, the vane consists of three subassemblies, a feather subassembly F, a tiller subassembly T, and a linkage subassembly L which connects the two. In this diagram the vane is set for a beat (upwind), with the feather trailing aft. Page 5 surmise, but were not able to verify, that there is a needle bearing on the top of T3 on which F2 rotates. There is definitely a washer under the drum F4, which may have been lubricated. The linkage consists of a U shaped assembly, L2, on which two threaded stops L1 are mounted. L2 can rotate in its bracket on T1. There is a second fixed stop, L3, which in the position shown prevents L2 from being rotated past the vertical. F1 F2 F3 L2 Self-Tacking It is clear from the layout that the F4 T1 T3 The Herreshoff vane gear, showing the locking mechanism. Parts not associated with locking omitted. The Feather Subassembly The feather rod, F1, holds the feather and the counterweight as shown in the photograph. It is rigidly attached to the shaft F2, which also has a fixed tab F3 and a rigid joint to the drum F4. The Tiller Subassembly The tiller plate T1 is rig- idly attached to the tiller rod T3, which connects to the actual tiller through the arm and crank mechanism visible in the photograph. A holding plate T2 is attached with three screws and serves to hold the feather subassembly in place. The Linkage Subassembly Without the linkage, the feather subassembly is free to rotate independently of the tiller subassembly. We Natural Tendency of Boat Correcting Action of Vane Wind Direction vane was designed to be self-tacking; otherwise it would simply lock in any position, as in the Iversen design. The self-tacking operation is as follows: the boat is trimmed to require lee helm, that is, left alone it will turn away from the wind as shown in the diagram. The natural tendency, as shown, keeps wind pressure on the starboard side of the feather, which holds the tab F3 against the port side stop L1 as shown in the perspective diagram. The vane is set to overcorrect this natural tendency. This turns the boat into the wind. At some point the wind pressure eases off the starboard side of the vane, the boat swings through the “eye of the wind” and assumes the opposite tack, in which the vane position and wind pressures are the opposite of before. Later developments involved mechanisms to keep the boat out of irons as she swung from tack to tack; called “guys” or “Liverpool Boys,” these used elastic bands to swing the main boom or jib club appropriately. There are no indications that “Robie” was equipped with these. Either Captain Nat accepted the problem or the use of the balanced rudder was sufficient to keep her on course until the vane “flipped” over. Locking The feather must be locked in position for runs and reaches (down and across wind). This is done very cleverly and with impressive economy of mechanism. The U shaped arm L2 is swung through a 300 degree arc as shown in the plan diagram; not shown is the fact that the fixed stop L3 then comes into play, resting against the bottom of the tiller plate T1. Swinging L2 down enables the feather subassembly to be rotated to any angle without the tab F3 hitting the stops. When the desired angle is set, the two threaded stops L1 are screwed down against the drum F4, holding the Page 6 feather subassembly fixed in relation to the tiller subassembly, as Captain Nat explained in his letter. Acknowledgements We are deeply grateful to the curator of the Herreshoff Museum, Carlton Pinhero, and his staff for their warm and kind hospitality during the day we spent studying the sailing models. Earl Boebert San Francisco Invitational Regatta 1999 45 year hiatus — it was his 7th grade shop project in 1953 and it sports a rare Lassel vane. Ron Thornhill from Ventura Calif. got his yacht wet for the first time in Spreckles Lake and commenced a furious pace of tuning and trimming and only finished during the races on Sunday. Rod Toesetti beautifully restored an early 1 950’s M tor the regatta and it proved to be unbeatable in light air. Rolf Faste flew down from Washington and stepped through the door to the clubhouse an hour before the first race and picked up his yacht rerigged and pretuned by Tony Marshall. Jim Harvey was also assembling his restored yacht just hours before Saturdays first race. The rest of us, Jason Spiller, Tony Marshall, Bill Davis and myself, had been campaigning our boats for several years in our regular M-Class races here and this obviously paid off in the final results. Editor’s Note The top three yachts after many great races, laughs and anguished looks, were only separated by 4 points at the final race. The Regatta Afterwards we retired to a fine dinner arranged by Tony Marshall and we were able to relive the moments when we thought we had control of these freesailers. I want to thank the V.M.Y.G. for donating a hat to every competitor. I believe this now annual regatta will grow every year in participation, enthusiasm and pure fun. The final standings were Jeff Stobbe, Tony Marshall, Jason Spiller, Rod Toesetti, Bill Davis, Paul Staiger, Jim Harvey, Earl Boebert, Rolf Faste, and Ron Thornhill. This is why your issue is late — blame Jeff! Seriously, I had the time of my life. Early arrivals began tuning up their boats on Wednesday for the weekend regatta. They were greeted with about every condition Spreckles lake has to offer over the next three days, including a little rain on Friday. Earl Boebert arrived with several of the V.M.Y.G. vanes and a genial buzz pervaded over the clubhouse as everyone pitched into coaxing the yachts to perform well off Spreckles Lake’s generally lee shore. Several yachts were launched for the regatta. Paul Staiger got his yacht in the water after a Jeff Stobbe The obligatory vintage pose by the participants.. Spreckles Lake, San Francisco, August 7, 1999 Page 7 Port Washington “A” Class Races Probably the largest fleet of “A” Class “pond yachts” to race against each other in the last decade sailed at Fort Washington’s Mill Pond on Sunday, August 15th. Ten of the large boats (6 feet long, weighing up to 40 pounds, and carrying over 1300 square inches of sail) competed. Almost “extinct”, several of the boats racing were over 40 years old, although recently there has been increased interest in the class. One of the boats raced was built this year in England, and is owned and raced by Bob Tantillo, a Mill Pond Model Yacht Club member. Model yachtsmen from southern New Jersey, Manhattan’s Central Park Model Yacht Club, and all over Long Island entered the event. The first place trophy went to Joe Cole, Williamstown, NJ; second place to Wally Ruff, Westfield, NJ; third place to Russ Page, Levittown, NY, all members of the Mill Pond club. Charles Blume USVMYG National Regatta 1999 marked the Vintage Model Yacht Group’s fifth National Vintage Regatta. The Detroit Model Yacht Club (DMYC) was privileged to conduct this year’s event at the Independence Oaks County Park in Clarkston, Michigan, just north of Detroit. The weekend led off with an optional day on Friday. A vane sailing demonstration and practice sailing was held at a small pond at the Independence Oaks Park. Ned Lakeman from Center Ossipee, New Hampshire brought a vane Marblehead and gave us a great demonstration of vane sailing. I also brought my Cheerio which has been converted back to it’s original vane configuration, but my vane gear is a very simple friction vane on the tiller post. Ned and I managed to get a few runs of the boats together, but his boat could self-tack for upwind, whereas mine could only be set for one tack at a time. Several of the weekend participants brought their boats to tune-up for Saturday’s racing. After having lunch as a group at Mel’s Grille, we all caravaned down I-75 to A. J. Fisher in Royal Oak. Bob Irwin is the Ned Lakeman pulls off a port tack start at the VM Regatta. Page 8 present owner and operator of the business, having inherited it from his father, who worked for the original A. J. Fisher. The group all marveled at the vintage machinery in Bob’s shop. Most of the machines were set up back in the 1930’s when the business was first established, and haven’t been changed very much since. This was truly a “vintage experience” to look at these machines producing brass stampings and turnings, just as if we walked into the shop back in the 1930”s. Bob was a very gracious host, taking time to explain the workings of the shop and answer the many questions from the group. Many of us took advantage of the opportunity to purchase some fittings and plans while we were at the shop. Saturday dawned clear and sunny, but no wind on the lake! Everyone was at the site early, anticipating the weekend’s events. We held the skippers meeting on time and introduced everyone to the group, then we waited for the wind to fill before Paul Eseman and Eric Reno, our DMYC race committee for the weekend, could set the course. The wind filled in about a half-hour later, and the Vintage Marbleheads started their morning of racing. The surprise of the morning was the 50 inch model of an Alden schooner converted to a vintage “M” sailed by Joe Cieri of North Plainfield, New Jersey. At the end of the morning’s racing, Joe had the lead score with a full keel boat with rudder attached to the keel. Wick Smith of Grosse Point Woods, Michigan was right behind Joe, sailing his grandfather’s Marblehead built in 1942 and restored by Wick just in time for this regatta. Saturday afternoon, the Traditional schooners and Open class boats had their turn on the lake. After a morning of light and fluky winds for the Marbleheads, the wind blew in the afternoon for the schooners. Ned Lakeman‘s new schooner “Pleione” had a perfect day with four first place finishes. Pleione definitely was set up for the weather. I was consistently behind Ned in “Brilliant”, which was sailing “rail under the water” most of the time upwind. Joe Cieri’s Alden schooner now converted to schooner rig was third, and Jerry Peters of Waterford, Michigan with a pretty model of the “Rachel” was just behind Joe. Sharing the water with the schooners and getting their own starts were the Open Class. Here the object was to establish a first race time, then try to match the same time each race. Skippers had to put their watches in their pockets and just sail their best estimate of time for each race. The Open Class format was suggested so that any boat could participate, regardless of speed potential. Several of the Marblehead skippers from the morning racing tried their hand at this contest. The leader at the end of the afternoon was Carl Olbrich of Lakewood, New Jersey, sailing a Spring Lake “double-ender”. Carl’s race times varied by just one second from race-to-race, a near perfect example of seamanship. Saturday night the skippers and their guests were treated to dinner at Eric and Luisa Reno’s house. After dinner, the Detroit Model Yacht Club surprised everyone with a fantastic slide show choreographed to music. Wick Smith and John O’Dell, along with Rob Boggs and myself had taken slide photos of the weekend so far and had them developed at a “one-hour” slide processing place. Wick secretly organized the show while everyone was having dinner. When we had everyone reorganize the room from dining room to viewing room, the skippers and wives finally realized what was about to happen. The show was a gathering of old model sailing and building photos from Wick’s family and Bob Irwin of A. J. Fisher, along with the slides of the previous two days events. Everyone enjoyed the glimpse at the early days of Detroit model yacht racing at Belle Isle. Sunday morning looked like a repeat of Saturday, except the wind cooperated by race time. The race committee, inspired by the vintage attire in the slide show on Saturday night, wore shirts and ties for the occasion! The temperature was a balmy 80 degrees in the afternoon, with strong winds after lunch. Forecasts were for up to 25 knot winds in the afternoon! The Marbleheads got in five more races before lunch time. Wick Smith and Ned Lakeman did very well on the second day to finish in the top two spots by the end of the regatta. Final Marblehead results were as follows: First Place, 22 pts.:Wick Smith, Grosse Point Woods, Mi. Second Place, 29 pts.: Ned Lakeman, Center Ossipee, N. H. Third Place, 32 pts.: Adam Lawall, Mt. Clemens, Mi. Fourth Place, 56 pts.: Harry Mote, Barneghat, N. J. Fifth Place, 59 pts.: Carl Olbrich, Lakewood, Page 9 N. J. Sixth Place, 64 pts.: Pete Peterson, Spring Lake, N. J. Seventh Place, 66 pts.: Thom McLaughlin, Tampa, Fl. Eighth Place, 68 pts.: Joe Cieri, N. Plainfield, N. J. Ninth Place, 79 pts.: Dave Harrington, W. Bloomfield, Mi. Charlie Roden, Colts Neck, N. J. was the only “High-Flyer” marblehead sailing. Charlie placed fourth in the combined standings (38 pts.) and first in the “High-Flyer” category. New for the 1999 regatta is a static judging category for the Vintage Marblehead class. The VMYG board felt that the craftsmanship that goes into the building of a vintage model should be rewarded as a separate category. Here are the top three builders in this new category: First Place, 8.4/10 pts.: Pete Peterson, Spring Lake, N. J. Second Place, 8.1/10 pts.: Thom McLaughlin, Tampa, Fl. Third Place, 8.0/10 pts.: Adam Lawall, Mt. Clemens, Mi. Sunday afternoon the wind really whistled for the schooners and open class boats. The schooners were only able to get two races in before we called it quits due to the strong winds. I was able to sneak up a bit on Ned’s score when he and Joe had a tangle at the leeward mark in the first race. Then equipment failure was starting to eliminate the field and we called it quits. The vintage schooner class scoring is a combination of display judging which considers appearance and workmanship, and the score on the race course. The display score is divided by five for the five categories, and the race score is divided by the number of races run. The final result is the combined finishing score of display and race scores. The results were as follows: First Place, 3.4 pts.: Alan Suydam, Farmington, Mi. Second Place, 3.5 pts.: Ned Lakeman, Ctr Ossipee, N. H. Third Place, 5.6 pts.: Joe Cieri, N. Plainfield, N. J. Fourth Place, 6.1 pts.: Jerry Peters, Waterford, Mi. The open class participants had dwindled from Saturday’s racing, but Carl Olbrich con- tinued his winning ways and ended up with a total time differential in five races of 2:41. Second place went to Harry Mote with a time differential of 4:25. All the members of the Detroit Model Yacht Club want to thank the regatta participants for a great weekend. Special thanks to my cohost Dr. Jerry Peters, our race committee Paul Eseman and Eric Reno, the entertainment committee Wick Smith, John O’Dell, and Robb Boggs, static Marblehead judges Earl Boebert and Bob Boggs, Static Schooner judges Harry Mote and Jim Skalnek, and especially Eric and Luisa Reno for use of their basement for dinner and the slide show. We had a great time and we are looking forward to next year’s national regatta on August 12 and 13, 2000 at Redd’s Pond in Marblehead, Massachusetts. Al Suydam Vintage Marblehead Coordinator’s Report Many thanks to Alan and Nan Suydam and other members of the Detroit Model Yacht Club for hosting an excellent National Vintage Regatta in Clarkston, Michigan on Sept. 25 & 26. The weather was perfect, the sailing site was excellent, and the social activities were outstanding. The VM racing was very competitive, and yet was protest free. This was the first year that VM static judging was held in addition to racing. There were several scratch built VM’s of outstanding quality that made the static judging a real challenge. Our decision to award separate trophies for racing and static judging appears to have been justified as there was only one sailor who won trophies in both racing and static judging. Some sailors place emphasis on racing while others get more pleasure from the construction phase of the program. Recognizing both talents by separate awards will continue in the VM Class. Now is the time to consider possible changes to the VM rating rules. Members are invited to submit rule change proposals to me at this time. Proposed changes will be published in the next issue of The Model Yacht and regis- Page 10 tered VM sailors will be allowed to vote on these changes at that time. The following issue of The Model Yacht will report the outcome of the voting. Please submit proposed changes to me in writing and include the rationale for the change. An important criteria for acceptance of any change is that the feature was in “general use” in the applicable time period (Traditional – 1945 and before, High Flyer – after 1945 and before 1970) although the need for a change can override this consideration if there are other strong arguments in its favor. My address is 19 Oak Glen Lane, Colts Neck, NJ 07722. Charlie Roden Pond Yacht Building Course at WoodenBoat Magazine’s School During the first week of August I taught a course in building vintage pond yachts at WoodenBoat Magazine’s School in Brooklin, Maine. The class was intended to expose students to the history of pond yachts, building techniques – in particular plank on frame, and have them leave with at least a hull ready to come off the building board. Ten students were in the class, which actually had a waiting list of significant numbers. The WoodenBoat School is located on a 60 acre ‘gentleman’s estate’ built in 1917 but left to deteriorate during the depression Since the early 1980’s WoodenBoat Magazine has published its magazine from the estates renovated house. The original boat house and dock have also been restored and overlooks a sheltered harbor on Eggemoggin Reach where approximately twenty boats, built at the school over the years, are moored. The school itself is in the original carriage house and stables. Now that facility houses a large variety of wood working equipment and enough space to conduct three to four simultaneous classes. I have been preparing for this class over the last two years. As many of you know, to An “Acadia” build a hull in six days is a daunting task. Thus to facilitate this I choose a simple boat, yet one that could take students through most of the considerations in vintage pond yacht building. I used John Black’s “Starlet” 36/600 design as an initial model because of its hard chine shape, hence minimum of complicated plank curvatures. I gave it more beam to allow for R/C equipment, a deeper draft fin keel, and a lead shot bulb to avoid the hazards of cast lead. By the time the redesign was completed and prototypes tested I decided that it had changed enough from the original source that it should have a new name. The class boat is now called “Acadia” in honor of the region in Maine where the WoodenBoat School resides. Probably the most rewarding class experience for me was the students. They were a very experienced group, seven of them having taken other WoodenBoat courses before. Several VMYG members were also in the class, Al Suydam and Doug Bebee. Doug brought a car full of vintage literature and Al brought his schooner “Brilliant.” Several of the other students also had pond boats with them, a vintage M that had been found in a basement in the 50’s and a commercially made 36/600 from the 30’s. We even held the “First Annual WoodenBoat Vintage Regatta” by sailing Al’s boat and my two “Acadia”s on a local pond. Many of the students in the other concurrent classes came, making probably 30 people attending and sailing till twilight. The class will be offered again next year. I am currently attempting to design a nonhard chine hull for the coming year, but no promises! Eventually I hope to have the class building vintage Marbleheads, but that also is down the road. If enough 36/600 Page 11 (actually in true vintage language, 36R) come out of this course, perhaps they can form a new vintage category for national events. Stay tuned and hope to see more of you in Maine in the coming summers. Thom Mclaughlin Red Cedar We sold out of the first batch of red cedar and re-ordered. The new batch is a little thicker to simplify fairing of hulls. The price is the same, fifty pieces of 1/8 in. by 1/2 in. by 5 feet for $60.00, shipping included. Please make checks payable to Earl Boebert, at the Editorial Address. Restoration Guide Bits of Oakum Vintage Hull For Sale Grant Slinn has a hull for sale. 63” LOA full keel boat, 26 lb. displacement. From the 1920’s from the looks of her, probably a MYRAA Class C or D boat. Contact Grant at 830 N. 4th Ave, Phoenix AZ 85003-1814. Vane Experience My simple self-tacking vane had a failure at San Francisco after five afternoons of constant sailing. I had a bad solder joint on the feather arm; this should probably be reinforced with a small triangle of sheet metal. Other than that, despite its fragile appearance, the vane performed well. I took Biff Martin’s advice and cut a bungee cord apart for its internal elastics. These worked very well for guying rubbers on the vane, the main boom, and the Liverpool Boy. The thin elastic strands can be doubled or tripled up to get the exact amount of “oomph” required. In the next issue we hope to write up our impressions of what it takes to free sail at Spreckles Lake. We certainly hope to see more of you there in May 2000! Cotton Sailcloth News Bill Bithell visited Great Britain and enjoyed the kind hospitality of Russell and Gil Potts . While there he located what appears to be a satisfactory cloth for cotton sails. He is testing the material now and we will report on results as soon as they are available. Sailmaking Services Maria Kay has offered her services as a sailmaker, and has shown John Show an impressive example of her work. Contact her at 527 Zion Hill Road, Atglen, PA 19310; 610-5937027; email: halfdan@epix.net Russell Potts has prepared a great guide on restoring old boats, based on work by the late Jack Drury. We are working on a glossary for North American readers. It will be available from Graham Bantock’s Sails Etc. in Great Britain. Ordering information will be in the next issue. Mill Pond Centennial Video A 20 minute video of the 1998 Mill Pond Centenial Regatta, including footage of Jim Wood’s spectacular library display is available for $20.00 from: Charles Blume P.O. Box 227 Port Washington NY 11050 Orders will help support this grand old club. Earl Boebert The Model Yacht is published three times a year by the U.S. Vintage Model Yacht Group. Copyright 1998-1999, U.S.V.M.Y.G. Reproduction for noncommercial purposes permitted; all other rights reserved. Editorial Address: 9219 Flushing Meadows NE Albuquerque NM 87111 Email: boebert@swcp.com Phone: 505 823 1046 Officers of the U.S. Vintage Model Yacht Group: President: John Snow Eastern Vice-President: Ben Martin Midwest Vice-President: Al Suydam Western Vice-President: Dominic Meo, III Southeastern Vice-President: Thom Mclaughlin Traditional/Scale Coordinator: Harry Mote Vintage M Class Coordinator: Charles Roden Classic “50” Coordinator: Dennis Lindsey Historian: Earl Boebert Historian: Charles Williamson Archivist: Jim Dolan Page 12 Technical Supplement Editor’s Note This article is excerpted from Thomas Moore’s Build a Winning Model Yacht, published in 1928. Moore was a naval architect and this work captures the state of model yacht design in the 1920’s. The procedures he described can still be used today to produce good-looking designs whose balance enables them to be sailed mostly “hands off” under R/C. I have edited the work with a light hand, removing mostly references to obsolete class rules. Figure numbers are from the book, and are not necessarily in sequence. The remainder of the words are his. The Lines The lines of a boat are intended to show the outside surface of its form. To accomplish this object on the flat surface of a piece of drawing paper, it is necessary to use a little imagination. It is necessary to imagine that our boat is made of a transparent substance that may be cut in the vertical and horizontal direction and even in a diagonal direction by planes and that wherever these planes cut the outside surface of our boat they are distinctly visible as a continuous curved line. The lines of a boat show one-half of the boat, the other half being exactly similar. There are three views, the profile, the half breadth or plan, and the body plan. The Profile This view is taken looking at the boat as she stands upright on the table before us. We see the edge of the deck at the side, running in a shallow curve from the stem to the stern. This curve is called the sheer. Then we see the outline of the boat at the center line running from the stem down to the keel and up aft to the stern. This outline is called the profile. Now imagine a plane passed vertically down through the boat at the center line, through the keel, and extending from stem to stern. Then imagine several planes parallel to the first one but, let us say, one inch apart. They will cut the surface of our model in a fair, continuous curve indicated by A and B in Fig. 16. These are called buttock lines. The Half Breadth This view is taken looking down at the boat as she lies bottom up on the table. The first distinct curve which meets our eye is the deck line sweeping out in a wide curve from stem to amidships and then aft to the stern. Now suppose the boat is painted white above the water line and green below. We then also see a shorter curve extending from a point on the center line below the stem head to a similar point on the center line near the stern. Suppose that where the white and green meet marks the line at which she floats in the water with all sails, spars and gear on board. Then this line will be the load water line (LWL). Pass planes through the boat parallel to the load water line both above it and below it and you have a series of water lines appearing as shown in Fig. 17. The Body Plan This is a view with the body of the boat standing upright and looking at her dead on end. We see first, the vertical line of the stem extending downward to the keel. Then we see the side of the boat extending from the deck amidships downward and curving in to meet the keel at the bottom. We really see the line formed by the intersection of a vertical plane passed through the Page 13 boat perpendicular to the base line and to the center line, as in sketch Fig. 18. The curved lines formed by the intersection of the surface of our boat and the above mentioned planes are called sections. It will be noted that in the case of water lines, buttocks and sections, lines appearing curved in one of the three views are straight in the other two views. Laying Off The prospective model yacht builder must either obtain a suitable set of lines or work out an original design and prepare the lines himself. In either case, it is necessary to study the characteristic hull form of the different types of yachts and to endeavor to acquaint himself with the various elements which, incorporated in the design, contribute the qualities of speed, stability, and balance. First, let us take the case of the prepared design, which will probably be chosen from one of the well known monthly magazines devoted to the sport of yachting. The design, as printed in the magazine, will no doubt be on a small scale, and the problem is to enlarge it to the size required for the model. There are two ways of doing this. If it is simply desired to enlarge the lines a given number of times—let us say, six—the way to do it is to lay out the framework of water lines, sections and buttock lines with just six times the spacing shown in the original drawing. It is best to use the small bow-spring dividers for making this spacing. The set of lines in Fig. 19 is given as an example. It is now desired to enlarge the above set of lines six times. Fig. 20, printed on a greatly reduced scale, shows how this is done. We first construct our framework of water lines, buttock lines, and sections. As will be readily seen, the water lines in our enlarged drawing are spaced six times the distance apart that they are in the original small drawing. The same with the buttocks and sections. The next problem is to get curved lines of the profile, halfbreadth plan and the body plan correctly superimposed on our large scale framework. We will start by obtaining points for the sheer line. Measure the distance on the small drawing, between the base line and the sheer line on Station No. 1 by means of the dividers. Set this distance up from the base line on No. 1 Station of the large drawing six times, and make a little dot. Repeat this process on the other four stations and at the extreme ends of the boat. We now have a series of dots through which we may draw a fair, continuous curve which forms the sheer line of our enlarged drawing. It may be well to state here that in drawing these long curves we will need several long, limber strips of wood, of approximately square section, called splines or battens which may be held in place on the plan by means of lead weights called dogs.1 These splines and dogs may be made at home or they can be purchased in a store where draughtsmen’s supplies are sold. Splines may also be obtained made of hard rubber or celluloid in lieu of wood. These are useful on the more abrupt curves. If these regular draughtsman’s materials are not available, very good results may be obtained by ordinary home-made pine battens held in place by flat irons, pins, or willing hands2. It is 1.Also known as ducks. — Ed. 2.Masking tape works as well. — Ed. Page 14 obvious that several battens, ranging in thickness from 1/4 inch to 1/16 inch will be useful, the thicker battens to be used on the flatter curves and the thin battens on the more abrupt ones. Now to tackle the profile. We measure up on each section on the small plan the distance above the base that the profile crosses the sections, and then transfer this distance six times above the base on our large plan and make a dot. A curve drawn through the dots gives us the profile on our large plan and we begin to see how big our boat is going to be. Now let us turn to the half-breadth plan and get our water lines drawn by measuring up on the sections in just the same way as we did for the sheer and profile. The actual terminations of the water lines may be obtained directly from the profile by dropping perpendiculars down to the center line of the half-breadth from the point where the profile crosses the particular water line with which we are dealing. Take the water line just above the load water line (Fig. 20). A A’ is the forward perpendicular and A’ is the forward termination of this water line. The after termination is found in the same manner. The sections should now be drawn in. It is no longer necessary to refer to our small plan unless we wish to do so as a check. We can take our plain dividers and, using Section No. 3 as a center line, we can set off the sections in the forebody to the right of this line and the sections in the afterbody to the left of the line. Measure directly from the halfbreadth in the large plan the width of the deck (from the center line up to the curve) on Section No. 3. Set this distance out to the right from Section No. 3 in the profile. Now, as the height of the sheer above the base varies forward and aft we must also be sure to set this half-breadth measurement at such a height as to have it correspond with the height of the sheer line at Section No. 3. We will get a point at C which fulfills the above requirements. It is now simply necessary to set out on the several water lines in the profile, the widths of the corresponding water lines at Section No. 3 taken from the half breadth. This gives us a series of rather close spaced spots through which we may draw a fair curve freehand. There are, however, ship draughtsmen’s curves for this work and it would help the accuracy and finish of our design if they were employed. It will be necessary to piece these curves together, as it is very rarely possible to find even among a whole set of these ship curves one that will lend itself to drawing an entire section, and have the line go through all spots. The other Page 15 sections may now be drawn as described for Section No. 3, and we have then the body plan complete. Our drawing is apparently sufficiently complete to allow us to proceed with the construction of the model, but can we be sure of its accuracy! It is inevitable, in the process just described, that small errors will be made in transferring measurements, and these enlarged six times have made a few of our spots appear uneven We have endeavored, in drawing our lines through these spots, to strike a general average, or to adhere to the most spots which gave us a fair curve. It is now necessary, to insure the symmetry and accuracy of our model, to obtain complete agreement between the sections in the body plan and the water lines in the halfbreadth plan. Any disagreements of this nature are best shown up by introducing a few buttock lines and three or four diagonals. The purpose of these lines is principally for fairing our hull, and their general nature has been previously discussed. By study of a set of published lines shown in Fig. 4 and from the above description of transference of “spots” it is believed that the reader can master the use of these lines without further explanation. It will be noted that the buttocks are really very similar to water lines, but are run vertically instead of horizontally. The diagonals are run at varying angles between the vertical buttocks and the horizontal water lines, but the general idea of a diagonal is to have it approximately perpendicular, so far as possible, to the surface it intersects. Beside the property of fairing the outside surface of our hull, the water lines, buttocks and diagonals all combine to tell us about the form of the boat. As soon as we have learned to interpret the form of the boat from these lines we can better understand the relation they have to speed, stability, balance and, last but not least, beauty. The Offset Table In the case of large vessels constructed in a ship yard, a full sized set of lines is made on the floor of a large building called the “mold loft.” These full-sized lines are taken from the drawing office set of lines which have been drawn to a scale of, say, 1/4 inch to the foot. A table of offsets of the lines of the vessel on sections, water lines and buttocks with a sketch of the conformation of the profile of stem and stern is furnished the mold loftsmen who now “lay down” the lines of the vessel, full size, on the mold loft floor. In large vessels the measurements are expressed in feet, inches and eighths of an inch, and an architect’s scale is used in taking these measurements, which are expressed, for example, 31—10—5, which is 31 feet 10 5/ 8 inches. The following figure (Fig. 24) gives the mold loft offsets of the set of lines shown in Fig. 19. It will be noted that the offset table is in two principal parts: the height above the base of lines appearing in the profile and the halfbreadths, or distances out from the center line of lines appearing in the half-breadth plan. Take first the heights above base. Under the heading “Sheer” are given the height of this line at bow or fore perpendicular, at each section, and at stern or after perpendicular, above the base. If we have our framework accurately drawn up we can set these heights Page 16 on the respective stations, draw a line through the spots and thus we have the sheer line in our new enlarged drawing. Now follow the same procedure with the buttock lines and profile. Now turn to the half-breadth part of the offset table. Under the heading “Deck” are given the distances out from the center line of the deck at side on each section. Set these distances on their respective stations on our new enlarged drawing, run a line through the spots and we have our deck line. Follow the same procedure with the water lines, each in turn. The process of fairing up between the lines of the profile and half-breadth plans should now be gone through as previously described while we are drawing in the sections on the body plan, the latter being made from measurements taken directly from the profile and half-breadth of the large plan we have just drawn. Some Hints in Regard to Design The model yachtsman will only obtain the greatest amount of enjoyment from the sport when he has learned to design his own model yacht, as well as to build and sail it. Although the first attempts at designing may not, in competition with the products of experienced designers, prove very encouraging, it is very evident that true insight into the art can only be gained in this way. In each successive design the imperfections noted in the sailing of models built to previous designs can be remedied, and at last, very near perfection, so far as pertains to matters of design, can be reached. If at the same time like improvement has been made in construction and rigging details and in handling, proficiency in the sport may be attained and the model yachtsman may feel the confidence in his boat and himself that he should have in competition with other proficient yachtsmen. our heads along such lines as these: “If I make my next boat a little longer and narrower, I will get less resistance at high speed, hence she will be better in strong breezes where my present boat is a little weak,” or, “My present boat has such an excessive amount of displacement that she is handicapped when in competition with newer boats. I will design a new boat with less displacement to trim these fellows that have been beating me.” Then we get out a pencil and a piece of paper and make some tentative freehand sketches of the new creation. Eventually we arrive at the time when we are standing before our draughting table on which is a nice clean sheet of cheap but durable detail drawing paper, ready to elaborate upon our little pencil sketch and produce a design which shall be the last word so far as our experience goes. It will be remembered that in connection with the determination of the form of our hull, the qualities of speed, stability, balance and beauty were mentioned. Of these qualities balance is undoubtedly the prime requisite, for no matter how speedy, or stable, or beautiful our craft is, unless she is able to sail consistently on a given course she will not be able to compete successfully with slower craft that can. And to sail consistently on a given course the boat must have balance in light airs, in moderate breezes and in heavy winds. Balance Assuming that both sides are alike, the model will be in balance when upright and at rest, floating at its designed load water line in calm water. The model will then be acted upon by two forces which are equal and, as they are acting in the same line but in opposite directions, no motion results. (Fig. 25.) Before the urge to create a new design comes to us we generally have had a number of thoughts running through Page 17 The weight of the boat W acts downward through the center of gravity CG of the model and is balanced by upward force of buoyancy B concentrated at the center of buoyancy CB. Now suppose the model to be heeled over at an angle of, say, 35 degrees. It is obvious that there has been no change in weight of the hull, nor, with respect to the hull itself, in the position of center of gravity. There has, however, been a considerable change in the form of the immersed portion of the hull and it is entirely possible that the position of the center of buoyancy has moved. Looking at the lower midship section of Fig. 25, we note that the center of buoyancy has made a lateral movement to B’ which places it in a vertical line with the center of gravity G. The model is at rest in an inclined position, held at the angle by an outside force. The point we now wish to bring out in the present discussion is the change in the fore and aft location of the center of buoyancy. If it has moved forward any considerable amount it means that our model has come up at the bow as she heeled over. If the center of buoyancy has moved aft it means that she has come up by the stern and that the bow has dropped. These changes of trim, as they are called, are very undesirable accompaniments of heeling as the model tends to lie at an angle to the direction of sailing which destroys the quality of balance, so essential in keeping a straight course. To avoid these changes of trim in the heeling model it is necessary to design the ends of the boat to suit each other. As a general example, sharp V-shaped forward sections should be balanced by deep V-shaped sections aft. Full or U-shaped sections forward permit generally fuller sections aft, and flat sections forward call for flat sections aft. Design In all we have said in the foregoing, it is evident that our boat should be well proportioned in a fore and aft direction if she is to do well. In other words, the body of the boat should be developed in fair, flowing curves from stem to stern without local bumps, hollows, or flat places anywhere. Suppose we have roughly determined upon a boat, of the following general dimensions: Length Over All 46 inches Length on LWL 33 inches Breadth 9 inches Draught 9 inches Displacement (about) 14 1/6 lbs (380 cu. in) We may lay down our drawing on a scale of 1/2 inch to the inch, which will be a convenient size for the purpose of study. On the above scale the load water line measures 16 1/2 inches. At the lower part of the drawing, draw a horizontal line AB representing the center line of the boat in the Half-Breadth Plan. On this line lay off the length of the water line, 16 1/2 inches, and divide this distance into eight equal parts, 2 1/16 inches each. At each of the nine points of division thus made, erect perpendiculars to the line AB, and number these perpendiculars, beginning at the right, 1, 2, 3, etc. These perpendiculars represent the sections. Above the line AB, at a distance somewhat greater than half the breadth of the boat, draw the horizontal line CD as a base line at the bottom of the keel. The draught of water is 9 inches which on 1/2-inch scale is 41/2 inches, so draw at this distance above the base line another horizontal line EF for the load water line. Displacement We have used the term displacement to denote the volume of the under-water portion of our boat. This volume and its distribution forward and aft may be represented by a curve called the “curve of areas.” This curve is, however, more accurately termed the “curve of sectional areas” and its ordinates represent the area of the cross-section of the underwater portion of the vessel at the point that the ordinate is taken and its area represents the volume of displacement. It will be readily seen, then, that if we can start by drawing this curve of areas, we will have progressed a long distance in determining the shape of the underwater portion of our design. In power propelled vessels it is usual to adopt a mathematical curve of areas. A method commonly used is to make the curve of areas for the forward half of the boat or entrance follow a curve of versed sines, while that for the after half, or the run, follows the Page 18 A C E 9 9 Q’ 8 G O’ FINAL CURVE OF AREAS P’ 8 SHEER 7 N’ 7 6 M’ 6 O P N Q M K J 5 BUTTOCK CB & CG OF LEAD CLR R DECK LINE S 4 T LOAD WATER LINE BILGE DIAGONAL H 4 3 3 U 1 BILGE DIAGONAL 2 2 BUTTOCK LINE 1 D F B HALF BREADTH PLAN BODY PLAN trochoid. In sailing yachts, the keel is, of course, temporarily omitted in reckoning the areas of the cross-sections for determining the ordinates of the curve of areas, and only the fair body form is used. It is generally desirable to make various modifications to the above mathematical curve, such as placing the location of the generating circle from 2 per cent to 5 per cent of the water-line length aft of amidships and fining off considerably the form of the curve aft. In the after body the actual curve of areas adopted generally lies somewhere between a curve of versed sines and the above-mentioned trochoid. The relation of the area of this curve and the area of the enclosing rectangle should come somewhere between .50 and .60. This decimal is called the longitudinal coefficient. By reference to our preliminary sketch we can estimate that the portion of the displacement devoted to the keel, i.e., that portion below the curved dotted line GH in the profile view (Fig. 26) is about 35 cubic inches, leaving 345 cubic inches for the volume of the fair body of the boat. If we have selected a longitudinal coefficient of .50, the length of our water line being 33 inches, the total area of the under-water midship section, both sides should be 345 ——————- = 20.9 sq.in ˙ .50 × 33 On the 1/2-inch scale this would be 5.2 square inches, and the area of the midship section, one side, would be 2.6 square inches. In the design shown in Fig. 26 we have placed the generating circle for our theoretical curve of displacement about 3 per cent aft of Station No. 5. This percentage times the water-line length of 16 1/2 inches on the 1/2inch scale gives about 1/2 inch. On the line AB set this distance off aft of Station No. 5 and erect a perpendicular below the line AB. On this perpendicular set off JK equal to 2.6 on a scale where 3/4 inch represents one square inch. On AB divide J9 and J1 into six equal parts each. On JK draw the generating circle with a diameter 2.6. Divide the circumference into twelve equal parts. In the left half of the circle draw JM, JN, JO, JP and JQ, as shown. Parallel to these lines and equal in length to them draw lines from the division points in J9 to M’, N’, O’, P’ and Q’. The points 9, Q’, O’, N’, M’ and K now denote the trochoid curve of displacement for our after body. On the right half of the circle draw radii from the center to the five divisional points on the circumference. Produce horizontal lines from these points on the circumference out into the fore body. Erect perpendiculars to AB at the five divisional points. Where these perpendiculars meet the horizontal lines through corresponding points on the circumference of the generating circle, will give a series of points K, R, S, T, U, V and 1 through which the curve of versed sines forming the curve of areas of the fore body will pass. Draw in this trial curve of areas. The next step is to sketch in Section No. 5, getting the actual area of the fair body (minus the keel below the dotted line GH) from our theoretical curve of areas. It is about 2.58. Use cross-section paper to check up on the area, slipping a piece of this transparent paper over the section just drawn and calculating the area by counting the squares enclosed by the curve of the section and the center line and the load water line. We have also as a guide in drawing this section a half breadth of beam of 4 1/2 inches. This will be somewhat less at the water line, say about 4 1/8 inches, measuring with our 1/2-inch scale. As the character of the midship section will exert a very strong influence on the whole shape of our boat it would be well to study the midship sections of published designs, with a view to selecting the characteristics most desired. In our present model we are designing a rather narrow, fine-lined boat, one that shall be easily driven with moderate sail area and, of course, are depending for stability principally on a comparatively heavy lead keel. Hence considerable depth of body is necessary. Now draw Section No. 3 and Section No. 7 similarly, being careful to give these sections the character they should have as previously discussed earlier in this chapter under the heading of “Balance. “No. 3 should be about 1.07 square inches and No. 7 should be about 1.80 square inches, according to our curve, but in the present design is fined down to 1.60 square inches, considering only the fair body and omitting the keel below CIH. These sections should be drawn in connection with the load water line, the shape of the latter having a controlling influence on the width of the top of the underwater portion of the sections. The shape of the load water line, together with that of the midship section, really determines the form of the hull. The half breadth and length of the water line are Page 20 given, and we are guided to some extent by the requirements of our curve of areas, but it will be necessary for us to be guided by experience as to the exact form of the curve itself. Broad, shallow boats are apt to have load water lines that are fuller at the ends than those of boats of deep, narrow body. The design we have before us shows a deep and rather narrow boat. The water line is kept rather fine at the ends to harmonize with the general idea of the form. We should now draw in our sheer line in the profile. This should be a fair, flowing curve, but the exact form of the curve is a matter to be dictated by the experience and artistic sense of the designer. A sheer that would look well on a boat with clipper bow and long, overhanging stern might not look well on a vessel with short, full overhangs. The following rule is given in Yacht Architecture, by Dixon Kemp: The length from the forward end of the water line to near the end of the stern overhang is divided into four equal parts. The height of freeboard at the forward end of the water line being taken as 1.00, the comparative heights of other given points in the length of the vessel are as follows: Points Steamer Schooner Cutter 0 1.00 1.00 1.00 1/4 .71 .73 .72 1/2 .57 .58 .55 3/4 .58 .56 .52 Aft end of LWL .71 .62 .57 1 .81 .72 .72 It will be noted in the above that the point at the stern end of the water line is put in as an extra point. If a rail is added above the sheer line, it should follow the sheer parallel until near the 3/4 distance, when it should become a little straighter, that is, the height of the rail is slightly less until the stern is reached. This results in a graceful taper between the two lines. The sheer line on our modern racing craft is considerably straighter than the curve obtained from the above values, but the latter are considered to be a useful guide. It would now be well to draw the profile line of the boat in the profile plan. The shape of the stem, forefoot and keel is very much a matter of taste, but the line should be so drawn that the fair body form of the boat is included within the profile and no undue bluntness to the forward ends of the water lines occur. In models it is well for the forward profile line to form a smooth, continuous curve from stem to keel without any sudden radical change in direction at any point. A sharp, well-defined ridge should be formed along the center line of the model at the keel and forefoot, as this sharpness is said to help the boat in going to windward. Likewise, the forward end of the lead keel should not be blunt, as in the case of many large yachts, although the center of gravity of the lead itself should be well forward of the middle point of its length. The rake of the stern post is a matter of importance with models. If the desire to cut away all useless deadwood were followed, as in the case of extreme freaks among the large racing craft, one could start at the keel at Station No. 7, run forward and up to a point halfway between Stations Nos. 6 and 7 and thence back to Station No. 7 at the point where the line GH crosses it. In this case, the rudder would be a balanced rudder with a vertical stock, located at about Station No. 81/2. In models designed and built in England, the foregoing form of profile aft is common practice. The short fin is said to give relief to pressures which form on the lee side, which pressures, in the case of a longer fin, have greater opportunity to exert an erratic influence, thus affecting adversely the steering of the model. The longer keel, as shown on the drawing, has, however, been used on many boats with good results. A moderate rake of stern post is desirable as with the rudder turned the current of water passing aft under the hull is directed upward, instead of being driven downward against its natural flow. On the other hand, an excessive rake of sternpost makes it very difficult to fit a suitable steering gear on the head of the rudder stock, as the angle of the latter with the deck is then very great. A moderate rake of sternpost is therefore the best. The after overhang is somewhat a matter of fancy, but should balance the overhang of the bow to give a good appearance and should be so drawn as to give good sailing lines with the model heeled down under sail. Page 21 It should now be practicable to sketch in the sections at Stations Nos. 1 and 9 in the body. Next, carry up the underwater sections that we have drawn in slightly rounded topsides to the deck. Take a few half breadths from the sections on the several stations in the plan view. We already have the exact maximum half breadth of the deck amidships, which is 4 1/2 inches on the 1/2-inch scale. Now spring a batten around the points thus formed and draw a fair curve for the deck line, giving a little width at B for the sake of strength of construction and any width we like at A across the stern. We can now transfer the half breadths of the deck to the body plan and draw more exactly the upper part of our sections, giving them the exact height they should have above the water line as taken from the sheer line. Now run in a diagonal across the bilge in the body plan, as shown in Fig. 26. Pick off the half breadth of these diagonals for the sections already sketched in and through the spots run a fair, free, flowing curve. Now using this diagonal and the load water line and deck line pick off the half breadths on Sections 2, 4, 6 and 8 and transfer them to the diagonal, the load water line and the deck line respectively in the body plan, making little marks on the diagonals, water lines and deck line. Now sketch in the new sections going through these marks and you have the body plan complete. In the profile draw a few water lines above and below the load water line and transfer the half breadths on each water line in the body plan down to the proper station in the half-breadth plan. Make spots on the sections and through the spots draw water lines. Do the same way with the buttocks. These should all come fair, but slight discrepancies may be expected when it is remembered that our sections are sketched in freehand and have not been accurately drawn by means of ship curves. Fairing the Lines. The correction of these discrepancies and the process of making all intersections in one plan agree with those in the other two—I speak now of the profile, half-breadth and body plans— is called fairing1. It is not possi1.Final fairing takes place on the building board. It is a process that many people, myself included, have a hard time doing on paper but which becomes perfectly obvious “in the round.” — Ed. ble to describe this process in detail by means of words, but if we have mastered the preceding text and have observed closely the method of bringing our plan up to its present state, we shall be able to fair the lines and make them accurate. Do not be afraid to introduce new diagonals, buttocks and water lines in any position where they will be an aid to the fairing process. The two main points to be remembered are: first, the lines of the hull must be fair; and second, the sheer, body, half-breadth plans and diagonals must agree in all corresponding measurements. Calculating Displacement and Center of Buoyancy We should now check over the question of displacement by drawing a new curve of displacement which shall take in the whole underwater portion of our hull and by getting the area of this curve, find our total displacement. We should first find the areas of our underwater sections on the body plan, keel and all, and set them up on the proper ordinates below the line AB. We find, as might be expected, that amidships, where the keel is located, we are running quite far outside our original curve of areas, and this, of course, is due to the added displacement of our keel. The area of the sections can be obtained by means of a machine called the planimeter, obtainable in most engineering offices2. Possibly one can be borrowed for a few hours. Failing that, however, we can obtain quite a close figure by the use of crosssection paper, counting the squares enclosed within our section curve and the center line and load water line. When our final curve of displacement is drawn, we proceed to find its area. Using Simpson’s Rule, we first find the length of the ordinates to the curve on Sections 1, 2, 3, 4, 5, etc., and multiply them by a series of multipliers 1, 4, 2, 4, 2, etc. The products we multiply by the number of stations distant from No. 1. The sum of the first series of products multiplied by the station spacing of 2 1/l6 inches and then by 1/3 gives us the volume of one-half of the boat. The sum of the second series of products multiplied by the station spacing and divided by the sum of the first series of products gives us the distance of the center of buoyancy from Station No. 1. The following is an example of the calculations based on our design: 2.These devices are now expensive antiques -Ed. Page 22 amount and position of the lead ballast that the boat is to carry. Sta. Area X Product X Moment 1 0 1 0 0 0 2 .25 4 1.00 1 1.0 3 1.09 2 2.18 2 4.36 4 2.10 4 8.40 3 25.20 5 2.93 2 5.86 4 23.44 6 2.75 4 11.00 5 55.00 7 1.90 2 3.80 6 22.80 8 .66 4 2.64 7 18.48 9 0 1 0 8 0 34.88 150.28 1/3 × 2 1/16 × 34.88 = 23.98 cu.in for one side 23.98 × 2 (for both sides) = 47.96 Now, as the scale is 1/2 inch = 1 inch, the volumes are compared as the cubes of linear dimensions. Accordingly, we must multiply 47.96 by 2 X 2 x2 or 8 to get the volume of our boat: We have a total displacement of 14.19 pounds. This is also the total weight of our boat with rigging, fittings, ballast, etc. It is possible, by careful workmanship, to construct a bare hull of the size of our boat weighing about 3 3/4 pounds. The deck, rigging, fittings, etc., will probably weigh about 1 3/4 pounds. We can assume a line for the top of the lead about as shown on the plan and then figure the volume in the same way we figured the volume of the under-water portion of the hull. The line of the top of the lead can then be shifted to make the volume of the lead and hence the weight (using .41 pounds per cubic inch as the weight of the lead) what we want and to place the center of gravity of the lead in the proper position. We should make a rough calculation for the fore and aft position of the center of gravity of the boat. This will insure that the trim of the boat will be as shown by the plans. We begin by assuming that the position of the center of gravity of the deck and hull is 2 inches aft of Station No. 5, and that the center of gravity of the rig is 1 inch forward of Station No. 5: 47.96 × 8 = 383.68 cu.in 383.68 × 0.037 = 14.19 lbs. (1 cu. in. of sea water = 0.037 lb) Now to complete our calculation we wish to find the fore and aft position of the center of buoyancy. This information is useful as it enables us to determine where to locate the lead ballast. The sum of the moments about the Station No. 1 is 150.28. Dividing the sum of the moments by the sum of the areas and multiplying by the common interval gives 150.28 × 21/16 ———————————— = 8.886 inches aft of Station 1 34.88 Multiply by 2 for our scale and get 17.772. The Center of Buoyancy is therefore 1.272 inches aft of Station 5. Center of Gravity In the foregoing we calculated the displacement and found the position of the center of buoyancy. We must now determine the Part Weight CG from Sta. 5 Moment Hull 4 1/4 x2 = 8.50 Rig 1 1/4 x -1 = -1.25 Lead 8 1/2 x 1.24 = 10.56 14 x 1.272 = 17.81 It will be noted from the foregoing that a position of center of gravity of lead has been assumed such that the total of the moments of the weights of the several parts of the boat about Station No. 5 is equal to the moment of the weight of the whole boat acting through the center of buoyancy about Station No. 5. This is done to bring the center of gravity of the complete boat and the center of buoyancy in the same vertical line. As explained previously, this produces equilibrium at the designed trim. The Sail Plan We have now completed our design except for the sail plan. It is assumed that the prospective builder will want to adopt a rig which has been found to be the most effective for model racing yachts. This rig is the jibheaded sloop rig with single jib. The next Page 23 question is area. The present design has been tried out with about 1,030 square inches, and has been found well able to carry this amount in open-water sailing. One should have as much as .25 of the total area in the jib. We must next determine the dimensions of our sail. [This is usually limited by class rules.] The length of the boom is generally between 1/3 and 1/2 the hoist of the mainsail. The mast should rake slightly aft. The boom may be approximately parallel to the water line about 2 1/2 inches above the deck and raking slightly upward at the outboard end. The leech, or outer edge, of the mainsail should have a slight convex curve. The jib should be about the proportions shown. If it is any higher and narrower it is often difficult to make it set flat, and if it is shorter and broader it is not so effective. The jib should set quite flat with only a slight fullness near the jib stay. The leech, or aft edge, must be flat without any curl in it. This result is obtained by the use of battens in the leech and by proper rigging the jib. Sail Area and Center of Effort We must now calculate the area of our two sails as shown in Fig. 15. They are triangles and the area is found by multiplying 1/2 of the height by the base. We must also find the center of effort of each sail and the position of the combined center of effort of the two sails. The center of effort is the point about which the pressure of the wind on the sail may be supposed to concentrate. It may be readily imagined that this supposition is largely theoretical, as with the wind meeting the sail at different angles when the boat is beating, reaching and run- ning, the center of effort moves forward or backward in a manner yet to be determined. However, as a relative means of obtaining sail balance the use of these centers is justified. To obtain the center of effort of a triangular sail, bisect the two sides and draw lines from the corners opposite to the points of bisection. Where these lines cross will give the position of the center of effort. If the mast is raked aft, it is best to take an axis perpendicular to the water line. The sail plan of Fig. 15 will give the method employed which, with the foregoing text, will enable the prospective builder to readily follow the several steps. There is a point to remember. If an axis or reference line is chosen which lies between the jib and the mainsail, the arm and consequently the moment of one sail or the other will be minus, while the other is plus. Center of Lateral Resistance of Hull When the position of the center of effort of the sails has been determined, we now return to the hull design, and taking the profile or outline of the under-water portion, we figure the fore and aft position of the center of this area considered as a plane figure. To do this we measure on each station, beginning with the one at the for. ward end of the load water line, the depth of the hull below the load water line and set it down; put the results through Simpson’s multipliers, which gives us the position of the point desired. This point is called the “center Page 24 of lateral resistance” and is so located that if a tack were driven in the edge of the deck in the same vertical line with the center of lateral resistance, a string attached to the tack and the boat dragged sidewise through the water, it would balance at this point—that is, there would be no tendency for the bow or stern to swing around from the position assumed at the start. (See Fig. 28.) The calculation for the center of lateral resis- tance for our boat is given in the following: Sta. Depth X = X Moment 1 0 1 0 0 0 2 1.75 4 7.00 1 7.0 3 3.73 2 7.46 2 14.92 4 5.87 4 23.48 3 70.44 5 7.87 2 15.74 4 62.96 6 8.50 4 34.00 5 170.00 7 9.00 2 18.00 6 108.00 8 3.62 4 14.48 6 100.36 9 0 1 0 8 0 120.16 We can show a spinnaker on our sail plan, which should be proportioned as follows: The hoist of the spinnaker is the distance measured from the deck on the foreside of the mast where the line of the luff of the jib when extended cuts the mast. The base of the spinnaker shall be from the forward side of the mast to the bowsprit end or point where the forestay meets the deck. We have now performed all the ordinary operations of designing a model sailing yacht, such as lie within the scope of this work. A great deal of additional work may be performed, such as investigating the balance of the hull when heeled and investigating the conditions of stability. Thomas Moore (1928) Curve of Areas, Versed Sines, Trochoids, and the Wave Theory In 1877, Colin Archer proposed his “Wave Theory” of displacement (non-planing) hull design. This theory was based on an important concept called the curve of areas. 533.68 4 1/8 × 533.68 ———————————– = CLR 18.32 in aft of Sta. No. 1 120.16 CLR is about right. The general practice is to make this distance from 2 1/2 per cent to 5 per cent of the water-line length with an average say, of 4 per cent. The distance from Station No. 1 to Station No. 5 is 16.50, so that CLR (center of lateral resistance) is 1.82 inches aft of Station No. 5. Now go back to the sail plan and draw in the hull definitely so that the CLR is slightly aft of the CE (center of effort). The amount of the horizontal distance between these two centers is determined by experience. Generally speaking, the distance should be greater on broad, full-bodied boats than on keen, sharplined craft. As our boat is distinctly in the latter category, it is believed that a “lead”—as it is called—of 1 1/4 inches of CE forward of The curve of areas for a hull is a graph which displays how the displacement, or underwater volume, of the hull is distributed along its length. The horizontal axis of the plot represents the load water line. The vertical axis represents the area of an underwater section of the hull at that particular point. The areas are taken off the section plans. In actual practice, the areas are sampled at fixed intervals (e.g., the stations) and a smooth curve is fitted to the points. In the drawing by Thomas Moore, the curve of areas is (as is common) overlaid on the half breadth plan. The curve of areas clearly has a strong relationship to the wave making and resistance of a hull. If the curve rises too sharply at the Page 25 bow, the hull will be “bluff bowed” and push water before it. Likewise, if it drops too sharply at the stern, there will be significant turbulence aft, as when a square sterned boat “squats” over the limit of its design speed. Conversely, a curve of areas that rises too slowly at the bow will lead to “plunging” and excessive pitching. Archer asserted (based on some fairly imaginative mathematical reasoning) that the curve of areas should itself resemble a wave line. It had already been learned by trial and error that the section of a yacht with the greatest area (the midbody) should be at about 6/10 of its length. Archer further argued that the curve of areas ahead of the midbody should follow the mathematical curve called a curve of versed sines and that after it should be what mathematicians call a trochoid. These curves are generated geometrically, as shown in the diagrams. They are both constructed from a circle and a line. The line is the length of the load water line and the circle is placed at the location of the midbody. The line is divided into equal parts (usually corresponding to the position of the stations; a’, b’, and c’ in the diagrams) and the circumference of the circle is divided equally into the same number of parts (a, b, and c) as the line was. The upper diagram shows how to develop the curve of versed sines. A series of rectangles is drawn (e.g. a to a” to a’) and the upper corners are connected as shown. The trochoid in the lower diagram is a little more complicated. Lines are drawn from the point A where the circle touches the line , such as A to a. A second line, of the same length and parallel to it (a’ to a”) is constructed. As before, the corners are connected with a smooth curve. The wave theory was attractive to Victorian naval architects because it was fundamentally geometric and therefore could be implemented using the drafting instruments of the time. It also had a nice mystical ring to it, and, most importantly, produced fast, steady, and good-looking boats. It fell out of favor in the early 20th century as more scientific evidence was gathered from towing model hulls in test tanks. Classic curves used in the wave theory of hull form. Upper, a curve of versed sines. Lower, a trochoid Page 26 Earl Boebert