The Model Yacht: Volume 10, Number 1 – Summer 2006

LINCOLN MEMORIAL POOL, WASHINGTON, DC NEWSLETTER OF THE U.S. VINTAGE MODEL YACHT GROUP VOLUME TEN, NUMBER ONE Summer 2006 Page 1 Editor’s Welcome elcome to this, the first issue of our tenth year of publication. To celebrate, we’ve increased the size of this issue and included some very special material. You may also note that the “look” of the newsletter has changed a bit. We have moved from Adobe Framemaker as our desktop publishing tool to Apple iWorks, and this has necessitated some minor adapting on our part. We’re hoping to get another ten years of use at least out of this software. This issue is special for another reason. Our good friend Mark Steele of New Zealand has reluctantly decided to discontinue publishing his magazine Windling World, which has given us much pleasure over the years. That, to invert the format of the old jokes, is the bad news. The good news is that Mark has agreed to continue Windling World as a column in The Model Yacht. Pictures, comments, and other contributions to Mark can be sent to our editorial address and we’ll forward them on straightaway. Our technical supplement this issue describes advanced plank on frame construction of a traditional, fin-keel hull. We also include one of the earliest articles ever written on selftacking vanes and have our usual ration of plans, hints and tips. Welcome aboard, and hoist a libation of your choosing in honor of our our tenth! Earl Boebert Ebbs and Flows The President’s Message Vintage Membership he VMYG annual membership is $20 for three issues of our newsletter – “The Model Yacht”. It is $25 for members outside the US. The VMYG lifetime membership is $100. Members also have access to technical assistance and vintage model plans. To subscribe to or renew our newsletter and services, send $20 or $25 check (payable to US VMYG) or cash ($100 life membership) to: John Snow, c/o US VMYG, 78 East Orchard Street, Marblehead, MA 01945. For detailed information, you can call me directly in Marblehead @781-631-4203 or visit the VMYG Web Page at: www.swcp.com/usvmyg 2006 VMYG National Events Changes Dates and/or locations for our two 2006 National events have changed. The Vintage M regatta is now October 6-8 at Spring Lake, NJ. It will include R/C VM and V36 racing with model construction judging. See the announcement and entry form in this issue or contact John Henson, Marbleheaders of Spring Lake Commodore, at 732-458-1370 or senlivjh@aol.com for details. Venue for our Traditional Sailing Craft/Scale regatta is now the Calvert Maritime Museum at Solomons, MD September 23 & 24. Check with Buck McClellan, Commodore of the Solomons Island MBC, at: shadow1954@earthlink.net Page 2 to confirm the activities planned for the Traditional event. Self-Tacking Vane Gear for Model Sailing Yachts Vintage Etcetera San Diego V36 Free-Sailing The San Diego Argonauts MYC is developing a V36 Class model group for free-sail racing. Ernie Mortensen, Club Secretary, is the lead for this activity. Contact him about this group and free-sail events at 858-729-0084 or erniejm@mindspring.com Vane Gear Prototypes Earl Boebert has developed a vane steering gear for free-sailing using modern materials. These will be tested at San Diego and Marblehead sites, with another sent to the UK VMYG for evaluation. Check with Earl when production versions of these vanes will be available for purchase by VMYG members. VMYG Material The US VMYG “how to” book and video package on plank-on-frame model construction, and the Yankee III J Boat model building book are available via the VMYG website. Also, copies of the 20+ page catalog of the 2004 The World of Model Yachts exhibit at the Museum of Yachting remain available. John Snow Editor’s Note his rare article, from Popular Science magazine in August 1941, fills a gap in our understanding of the development of the self-tacking vane. Vane steering for model and full-size boats was invented by Nathanael Herreshoff in 1875. The original arrangement can still be seen in a patent model of a catamaran in the Herreshoff Museum in Bristol RI. The vane (a turkey feather in the original model) rides on the masthead and its motion is transferred to the rudder through a shaft and a set of bellcranks. The first self-tacking vane, as John Black notes in this article, was invented by Ted Houk in 1940. The self-tacking feature took advantage of a clause in the free sailing racing rules that allowed a boat on a beat to be turned at poolside without stopping. Houk’s vane was a “three pivot” configuration, later known as a “Fisher” vane, in which each arm Page 3 was on a separate pivot, the third pivot being that of the vane body. Gus Lassel, who is not mentioned in the article, devised the “two pivot” configuration shown here, where the of each tack to compensate for possible asymmetries in hull or rig. Earl Boebert John Black’s Text othing in a century of modelyacht racing has added more thrills to the sport than the vane steering gear, which is today to model yachting what the jibheaded mainsail is to full-size yachts and the front steerer is to ice boats. Its advantages are: 1. The mainsail may be sheeted very close. 2. The jib may be eased off to allow a perfect flow of air between the sails, but will still retain its full lifting power. 3. The model is kept on its course at all times unless the wind changes. 4. The advanced type of gear illustrated allows of tacking with a pole, which gains many seconds in sailing to windward. This particular type of gear was invented by Dr. T. W. Houk, of the Seattle (Wash.) Model Yacht Club. Its ingenious self-tacking fea- feather arm and the vane body pivot on the same axis. This has the advantage of taking up less fore-and-aft space, allowing greater movement of the sliding rig which was the other element of the “Lassel system” of free sailing. The design shown here, which we have previously been unaware of, adjusts the relative angle of feather and tiller by changing the distance between pivots. This approach has the disadvantage that the relative angles on both tacks are the same. The final form of the Lassel vane permits independent adjustment ture, which is new, throws the vane into position when tacking, without manual adjustment. The action is such that the vane always remains in the proper relation to the amount of helm, which is adjustable. To be Page 4 successful, however, such a gear must meet three requirements. First, its construction must be light, yet sturdy enough to prevent the gear from altering its set when under way. Stainless steel is best for the metal parts. The vane itself should be made of balsa wood. Second, the ratio between the gear and the tiller arm must allow the vane sufficient leverage to keep the rudder in position. A ratio Page 5 Upon the Seattle bar is mounted the slide (7) on which is pivoted the auxiliary arm (8). This carries at its closed end a pin that engages the inner end of the vane arm (9). On the longer side of the auxiliary arm is fitted a sliding weight of one to two ounces. A sliding lock (10) is provided on the vane arm. This engages the clamp to lock the vane directly to the Seattle bar for reaching and running. The vane arm is held on the stem (3) by a split wire ring (11). The various settings are indicated in the diagrams, but exact adjustments will be found only after several trials. The disk (12) may be graduated for future reference, if desired. Take care when tacking to fill the jib, and to make sure that the balancing weight has moved to the same side as the sails. For guying, both the latch and the sliding lock are disengaged, and the Seattle bar is set as may be necessary by means of the clamp (13). John Black (1941) of 60 percent for the tiller arm and 40 percent for the disk arm (2) will serve as a basis for experimentation. These proportions will vary according to the shape of the hull, and the size of the rudder and sails. The third essential is that the vane itself must have sufficient area to control the rudder. It is better to have the vane too large than too small. Several sizes should be made, the larger ones being used in light winds. In the gear illustrated, the vane is pivoted upon a needle point spindle (1). The disk arm (2) has a short pin which engages the wire tiller arm. The disk arm and the disk are soldered to a length of 1/4″ brass tubing (3) mounted upon the inner spindle (4), which is a pointed steel rod fastened securely to the deck. A brass plug is sweated into the top end of the tubing to form the inner bearing, and at the top receives the outer spindle (1), which may be a steel phonograph needle. The Seattle bar (5) is fixed to the clamp that carries the latch (6). The latter is used to lock the Seattle bar for sailing to windward. The clamp (13) is locked upon the stem (3) by a thumbscrew and nut. Page 6 s my little magazine Windling World proceeds onward at a rate of knots towards closure after eleven years, an offer to have a column on a regular basis dedicated to `windling’ in The Model Yacht has eventuated. Though several readers of The Model Yacht also subscribed to Windling World, who knows, perhaps some WW readers may now become subscribers here. Windling for those who don’t know, is the use of model sailboats for pleasure, relaxation and fun, as opposed to racing, serious racing as such which has often resulted in arguments and dissension, quoting of rules, protests etc in the International classes anyway. Windling, a phrase I coined to differentiate our style and manner from racing is perhaps more easily defined as the model yacht version of cruising which let me add, can be done with any model sailboat whatsoever. Relaxation and friendship are two of several plusses in the windling scene. It’s all only a question of attitude. I have been continually gob-smacked within the eleven years of Windling World publication, at the volume of scale sailing models being built, not only in New Zealand but in Queensland, Australia particularly, some having been built by perfectionists over a period of years, others by guys who build quicker for whatever reasons, but nonetheless turn out boats that look good and sail well enough in a much shorter span of time. Both types of people I admire greatly. Keith Murrow’s 50” Schooner Monica Oh yes, oops I nearly forgot, particularly with scale or stand-off scale RC models, having a good imagination (remember your boyhood days) helps and as so many of us return to model yachts, now with the attraction of radio control opens a whole new world, but only if you let it. For windling to gain and maintain momentum, every club or group should have a type of person that I refer to as being a bit of the `Boatus Uninteruptus’ kind, living to build and sail, always with the next project in the mind, people like Ron Rule of our Auckland group, the Ancient Mariners (and we are not a club and charge no fees) because there is always a new boat on the pond or on the horizon, another one in that mold being Keith Murrow of Hull in Yorkshire, UK. On the flip side in the master shipwright class are people like Ian Hunt in Sydney who may turn out maybe only half a dozen boats in his lifetime, but they are all absolute masterpieces in every sense of the word, his 10’ 6” long Sindia about a year off completion, and New Zealand’s Malcolm Wilkinson very much in that classification. Page 7 Before I close, let me if I may, impart another couple of qualities useful in the character shaping of a true windler, having a sense of humour and not taking yourself or life too seriously…and while you pond(er) on what to build, don’t dilly-dally until the pond or lake or river or your choice is too damn crowded with others. Quick-build a small sloop or dare I say it, go out and buy a kitperhaps one of those snap together Japanese or Taiwan models (like a Thunder Tiger Victoria) and get windling. Believe me you will thank yourself for doing so because very soon you will be windling, not just thinking about it! Mark Steele Ron Rule’s Pirate Ship Frankln Delano Roosevelt loved the sea and yachting, both full-size and model. A series of races across the Hudson river by the Roosevelt family was reported in Yachting magazine in 1921. This picture is from around 1930; our thanks to Rich Matt for finding it. Page 8 Thomas Darling’s 20-Rater, designed to the R Class rule at one inch to the foot. A.J. Fisher’s Chico II, redrawn by Al Suydam Archie Arrol’s design for the Detroit News workshop program, which we have given the name DN36. Page 9 receiver, through it to the rudder servo, and directly to the sail servo. Columbia? Well, Not Exactly Last issue we printed plans of what we thought was Nathanael Herreshoff’s Columbia, taken from an article by W. J. Daniels published in the 1920’s. Sharp-eyed reader Steve Crewes notes that these are really the lines of the very similar Defender. More, and the proper sail plan, in the next issue. V36 Full Size Plans The plans shown on the opposite page for Vintage 36 boats are available from us. The 20-rater and DN36 plans are single sheet, lines and sailplan only, $25.00 postpaid. The Chico II plans are three sheets with with construction, rig and radio details, and are $40.00 postpaid. Any set on CD (tiff format) is $15.00. Orders to “Vintage Plans” at the masthead address or through PayPal to boebert@swcp.com Try a “Y” Harness If your sail servo seems anemic, stutters, and cuts out when the going gets heavy, you may be a victim of your receiver’s Battery Elimination Circuit or BEC. The BEC is there to prevent damage from electrical overload, and cuts power when it thinks too much current is being drawn. As we used to say in the computer business, that stutter is not a bug, it’s a feature. The answer is a “Y” harness, which bypasses the BEC. The left diagram shows the conventional hookup. The solid line is the black wire, the dashed line is the red wire, and the dotted line is the “other color,” usually white, yellow or orange. In this diagram all power goes through the receiver. The right hand diagram shows the “Y” harness, where the battery power is spliced into the line connecting the sail servo to the receiver. Power then is provided to the Please contact us at the editorial address in the masthead before ordering, so we can make sure it will fit and give advice on making your own feather, etc. And allow three weeks for delivery, as we have to have the parts cut and do some drilling and assembly. Earl Boebert Receiver Battery Rudder Servo The next iteration of the USVMYG vane is shown in the the photo below. The vane can be used as a single unit as shown, fixed to a recessed transom, or, since it is made of easily worked ABS plastic, mounted to the transom or deck of an existing boat. Owing to the reduced prices of laser cutting, we can offer these for $35.00 plus postage. This is an economical way to experience the genteel lunacy that is free sailing. Just dig out that obsolete 36/600, IOM, US 1 Meter or M boat, take out the radio gear and install one of these. Sail Servo Sail Servo Receiver The USVMYG Vane Battery Rudder Servo Page 10 Page 11 This interesting 10-rater was designed by Mr. J. Gordon Kelly of Kingston, Ireland and documented in an issue of Rudder Magazine for 1896 and again in Frank Nichols’ 1902 classic How to Build a Model Yacht. She is notable for her modern hull sections and twin, or “goal post” keel, which was used on the 1992 New Zealand America’s Cup boat (the “Little Red Skiff”) which came within a bowsprit and a protest of being the the challenger. 57.25 in LOA, 40 in LWL, 1457 sq in sail area. Thomas Darling’s Text Technical Supplement Editor’s Note ur Technical Supplement this issue is a chapter on plank-onframe construction of a traditional fin-keel boat, taken from Thomas Darling’s 1936 classic, Miniature Racing Yachts. Thomas Darling was, like John Black, an industrial arts teacher, in his case in Montclair, New Jersey. He also evidently had a background in naval architecture. He was an active skipper and writer during the 1920s. His most famous design was for a model to the “R” Class rules under the old Universal Rule. Two versions of these appeared, one at an inch to the foot, which was also known as a “20-rater” because the “rated length” came out at 20. The actual length was 36 inches, making it a handsome candidate for the V36 class. The second was at an inch and a half to the foot, 55 inches actual, which (if scaled down to 50 inches) would make a fine Vintage M. It is the second, larger of these that Darling is describing in this chapter. By 1936, when his book was published, it was seriously out of date—model yachting had been revolutionized by the rise of the Marblehead class in the early 1930’s, and hardly anyone sailed the classes of boats he described, all of which enjoyed their heyday a decade before. As a result, the book had limited sales and remains today one of the rarest of the model yachting texts from the Vintage era. His knowledge, experience, and skill as an author and draftsman make it a classic, and we are happy to be able to present this excerpt, lightly edited for clarity and consistency. The description begins with the keel. Earl Boebert he keel must be built up, as shown in Figure 1, to insure getting the grain of the wood to run in a direction most suitable for strength. A section of the keel is shown at B, Figure 3. Note that the keel consists of four distinct members. A is, the keel proper and includes the stem in this instance. B is the stern post. C is the knee or deadwood. D is the horn-timber or fashion piece. Observe how the different members are fitted to one another. The keel butts against the stern post, the horn-timber lands on top of the stern post, and the knee is dovetailed into the keel and the horn-timber as illustrated. Make a template for each member of the keel. These templates can be made of heavy card or Bristol board. Select the material you desire to use. If the boat is to be planked with white pine or cedar, and is to be finished bright, use oak. Should you desire to use mahogany, baywood 1, or indoako2 for planking, use pieces of straight-grained Honduras mahogany. Material should be medium hard, free from knots and checks, and well seasoned. If white pine is used. increase, the dimensions given here, 20 per cent. Label the pieces of material with the names of the several parts. Draw a center line from bow to stern on keel top bottom. Apply the templates, and draw the outlines using a hard, sharp pencil point for. marking. The stem head is allowed to project 1 inch for setting up on mould-board. Shape the several parts, and assemble them. Use a waterproof glue to secure the members, at first. Now bore for, and drive drift bolts through the deadwood, or knee, and stern post, as shown at I, in Figure 1. These drift bolts are made of No. 40 brass wire. Lay off, number and mark for recognition the sheer line at the stem (see G, Figure 1), each station or section, the L.W.L. and the rabbet line. Square the station marks across the top and bottom of the keel, and mark the plumb lines on each side. Bore the holes for the keel bolts as shown at J, Figure 1. Groove the stern post, and bore the hole to receive the rudder post. Observe that 1 A name used for several varieties of mahogany—Ed. 2 A hybrid of mahogany and teak, now quite rare—Ed. Page 12 the keel bolt at station No. 12 will help to secure the several parts when driven. Get out the transom. This member, shown at E, Figure 1, can be made of the same material as the keel, or may be made of a wood with a color which will contrast with the planking material. Lay out and mark the sheer line and the rabbet line. Make sure that you have enough extra material to permit working a taffrail on the transom, and for camber or crown of the deck. Refer to H, Figure 1, and to R, Figure 15, when studying this shape. If there is fear of leakage at the joints of the several members of the keel, stop-waters can be bored for, and driven as shown by the circles in Figure 1. These will prevent seepage of water. They can be made of 3⁄8-inch white pine. Stop-waters are hardly necessary in a boat such as a miniature because the hull is hardly ever left in the water long enough for this action to take place, although it- is well to know about this method of preventing leakage. Lay the keel aside until the moulds are ready. The next job is to get out the moulds 1. Study Figures 2, 3 and 4. These figures show how allowances must be made for the thicknesses of the planking and the frames or ribs. Refer to C and D, Figure 3, especially, for this information. Study Figure 5 to obtain an idea of the way allowances are made at the top of each mould, to permit it to rest in the proper position, on the mould-board2. Proceed in this way: Draw a line 1 inch above the sheer line,at the stem head, parallel to the L.W.L. from bow to stern. This line represents the top face of the mould-board as shown in Figure 5. Each mould, or section shape, must be made large enough to extend up to it. Draw these extension lines at each section on the body plan. As the frames and planking 1 Also known as “shadows.”—Ed. 2 Also known as the “strongback.”—Ed. Page 13 Figure 1 Fit the transom to the horn-timber of the keel, cutting a socket to receive the timber end. This is shown in Figure 1, and Figure 15. Secure the transom to the keel using glue and ½-inch No. 3, flat head brass screws. The screws can be driven from the top of the transom, as they will be covered by the deck later. It is recommended that poplar, 3⁄8 inch thick, be used for moulds. This material should be well seasoned, and free of wind. Plane a working edge on the stock, and mark for recognition. Mark the center line of the mould on the working edge, and on each face. Lay out and cut each mould to shape. Be sure to mark the sheer line, and load water line on each one. Number each mould. The mould-board is next in order. Procure a well seasoned, straight piece of stock, and dress it on four sides, cutting it to these dimensions: 1¼ inches × 3 inches × 61 inches. Lay off seventeen stations on the mould-board, number each one, and gaugemark a center line. Its appearance is shown in Figure 5. Figure 2 will be 1⁄8 inch each in thickness, ¼ inch must be removed fromthe moulds to permit the frames to lie in place, and that the completed hull may conform to designed measurements. Take a pair of bow compasses and set them to ¼ inch. At the point where each water line touches the section or station outline, Figure 3 strike an arc. Now draw a line, from sheer line to keel, tangent to these arcs, and the outline of the mould will be obtained. Pick up each mould shape by tracing on strong onion-skin paper, working from the vertical center line. Keep in mind the fact, that for a boat to be a consistent sailer, both sides of the hull must be made the same shape. Make a template for each station. Now, set up the moulds. Use a small block in the angle formed where the mould and the mouldboard meet. Drive two screws into the mould, and two screws into the m o u l d – b o a rd . Figure 4 Page 14 This method of fastening will prevent the mould swivelling or shifting. Moulds 3, 4, 5, 6, 7 and 8 are placed forward of the station marks. Moulds 9, 10 and 11 are placed so that they straddle the station marks. Moulds 12, 13, 14 and 15 are placed aft of the station marks. It will be necessary to determine where the bearding line will come. This line is formed by the meeting of the inner faces of the planks and the side face of the keel. Refer to B, Figure 5. The simplest way to obtain the spots for the bearding line is to draw a cross section of the keel at each station, as shown in Figures 2, 3 and 4. Figure 5 Cut the rabbet, using a piece of planking to measure its depth. Bevel the keel at each station, first, and then remove the waste wood in the areas. between, afterward dressing the surface between the rabbet line and the center line of the keel, fair and true. Replace the station marks, wherever they may have been cut away. Notch out moulds 3, 4, 5, 6, 7 and 8 forward and 13, 14 and 15 aft, to permit keel to drop down in place. Bevel the bottoms of all moulds, and fit the backbone into its true position. A split block holds the stem head in place, and a block is fitted under the transom to support it. Fit and secure blocks in each angle formed where the moulds and the backbone meet. Getting out and bending the frames are the next jobs to demand attention. The frames for this boat are 1⁄8 inch × ¼ inch. For a larger boat 1⁄8 inch × 3⁄8 inch is recommended. The frames are to be spaced at each station, and one in each room between. Ash, oak, or elm are the best materials to be employed for these members of the hull. It should have clear, straight grain. After steaming or boiling for about two hours they can be readily bent to shape. Tack them to the moulds, temporarily, with ½-inch brads. After they have cooled and set, remove them from moulds, number each one, and lay them aside. It will be necessary to make provision for the lower ends of the frames. Sockets can be cut so that they are ” boxed ” in as shown in Figure 2 and Figure 3, or a through mortise can be cut, allowing the frame to pass directly through the backbone. This arrangement is Page 15 ten to the frames as the waste wood is removed, testing for an accurate, fair fit. Most of this bevelling will have to be done on the forward and after frames. The hull is now in frame and ready to receive the skin or planking. It can readily be seen that the longitudinal system of planking is most practical for a boat such as this, and is the one generally employed. Figure 6 shown in Figure 4, and at M, Figure 6. The last-mentioned method cannot be used where the sections are too V-shaped. The moulds must be notched or recessed to take the clamps and stringers. The clamps are pieces running from the stem to the transom, located a distance equal to the thickness of the deck beams and the deck, below the sheer line. They are 3⁄8 inch × 3⁄8 inch yellow pine. The stringers are pieces running from just under the clamps at the stem, to just under the clamps at the transom. Use ¼ inch × 3⁄8 inch yellow pine for these parts. They are located midway between the clamps and the keel top amidships. Each mould must be cut out to receive them. When fitted the clamps appear as shown at F, in Figure 3, and at C, in Figure 7. The stringers are shown at E, Figure 3, and at S, Figure 7. Fasten them at stem, transom, and timber heads with screws. The plank fasteners will pass through the clamps and stringers at other points where they cross the frames. Pattern-makers’ white pine1, cedar, indoako, baywood, or mahogany will prove to be satisfactory woods for this purpose. The materials should be 1⁄8 inch, full, in thickness, straight grained, uniform in color, free from knots and checks, and well seasoned. Each plank should be in one length from bow to stern. The plank nearest the ballast is called the “garboard.” The one next to the garboard is the “first broad,” and the next one is the “second broad.” The plank nearest the deck line or sheer is known as the “sheer strake.” There are other names such as shutter, binders, etc., but we will not consider these, because our method will be to put one plank on after the other, beginning with the garboard and finishing at the sheer strake. Check all parts carefully for fit and alignment. Secure frames in place using glue and screws at heels. Use brads to hold frames in place on moulds. Before the planking can be fitted the frames must be bevelled to allow the planks to lie snug on them. This work can be accomplished with a file. Apply a bat1 Figure 7 Very rare and expensive these days—Ed. Page 16 There are several things to be borne in mind as the planking job progresses. Each plank must fit its neighbor without forcing or strain, butting up to it with an absolutely tight joint. If the plank ends are forced upward or downward, hogging or drooping will surely take place. Each plank should be worked out in pairs as the job goes forward, and each should be “hung” or fastened in place on the boat at the same time. Proceeding in this manner, all chance of undue strain can be avoided. Figure 8 Wherever the turn of the section requires that the plank be hollowed out to allow for a good snug fit to the frames, this hollowing may be done with a “violin plane,” or the hollow may be made with coarse sandpaper. Great care while working will repay the builder, in large measure, later on. The fastenings recommended are Japanese round toothpicks. Ordinary straight brass pins are sometimes employed. At the plank ends small ¾-inch brass screws will hold very well, as there solid wood is found. A No. 51 twist drill will serve to bore for the fastenings, although the size of the toothpicks obtained may make it necessary to use a different size. Refer to Figure 8, study the layout of the planking and note that thirteen planks to a side have been used. A good idea of the direction in which the seams of the planking will run can be obtained by a study of the diagonals in the body plan, although it may be necessary to make some changes as the planking goes forward. Notice that the fifth plank from the sheer line is about at the water line, its forward end about at the turn of the stem, and its after end terminates at the knuckle, which is made by the joint of the horn-timber and transom. The girth, or measurement of each section from rabbet line to sheer line, is different. The problem is to divide each section girth up, so that the same number of planks can be fitted. When taking these girth measurements remember to keep the top edge of the sheer strake 1⁄16 inch below the sheer line mark. This 1⁄16 inch with the 1⁄16 inch which will be removed when bevelling,will bring the top corner of the deck edge down to the sheer line. Page 17 Figure 9 Figure 10 The garboard should be laid. out first. Measure up 25⁄8 inches on station No. 12. Take a thin, pliable batten and adjust it fore and aft so that it lays fair and true along the frames, getting it as nearly parallel to the water line as possible. Do not force the ends of the batten, but let it lie naturally. Mark the frames. This will be the top edge of the garboard strake. Now, to obtain its shape, to enable you to lay it out on the planking material. There are several ways of doing this, such as cutting cardboard templates, pressing stiff paper against the rabbet line, then cutting away until it fits, etc. The surest and most workmanlike way is to take a “spiling.” The spiling method is employed by the boat builder. Study Figure 9. A thin batten, narrower than the plank to be worked out, with a length governed by the length of the plank, is secured to the frames or moulds. The center of each frame or mould is lightly marked on the “spiling batten” and numbered. Set a pair of wing dividers, or for this small job, a pair of bow dividers, with their points apart equal to a greater distance than the space between the edge of the spiling batten and the shape to be obtained. Keep the points of the dividers parallel to the center line and prick off a “spot” as shown at 10, Figure 9. Do this at each station. Circle the spot, that it may be readily located again. Remove the spiling batten from the frames, and secure it to the planking material. See Figure 10. Tack the spiling batten to the plank. Draw the station center lines on the plank. With the dividers set as before prick off the spots at each frame number. Line off the edge of the plank, using a thin batten tacked in place, as a guide. The end shapes of the planks can be obtained by offering them up to the rabbet, and marking, when the plank is tried in place. Do not be alarmed at the peculiar shape the plank edges may show when lying flat on the bench top. Watch that the edges show fair, with an even sweep, when they are tried on the frame of the boat. Cut the garboard planks to shape, and fit them to the rabbet, carefully. Varnish the rabbet, and apply varnish to the plank edge. Fasten in place. Lay out the “first broad.” Measure up ¾ inch on station No. 9, apply the batten as before. The top edge of the first broad should end at about station No. 5. Allow it to run naturally in the after-body. Sight for a true, fair sweep. Obtain the shape, line out the plank, cut in Page 18 Figure 11 shape, fit and fasten in place. Use a liberal quantity of varnish on plank edges, and dip the toothpicks into waterproof glue before driving. If it is decided to use pins as fastenings, anneal by heating and quenching in water. the nearest 32nd. Divide the distance between the point marked 17⁄32 inch and the one marked 24⁄32 inch into seven equal spaces, and label them 18⁄32 , 19⁄32 , 20⁄32 , 21⁄32 , 22⁄32 , and 23⁄32 as shown in Figure 11. If the end of the scale is placed against the top edge of the first broad, the scale being applied at any frame between station No. 5 and station No. 9, the number on the scale touching the lower edge of the sheer strake will give the width for each plank, at that frame to the nearest 32nd. Now, lay out the sheer strake. It is also to be ¾ inch wide at station No. 9. The taper on the planks, fore and aft, is known as “diminish.” A “diminish scale” is shown in Figure 11. Suppose the remaining space or girth to be filled at station No. 9 is 7½ inches, and is the Another method of laying out the taper or greatest girth. Three strakes, the garboard, diminish of planking is illustrated in Figure first broad, and the sheer strakes have been 12. To make this scale draw a straight line as accounted for. Ten strakes remain to be laid X—Y. Scribe a semicircle with a radius equal out. Lay off 7½ inches on a pliable batten. If to the width of the plank at the greatest girth, this measurement is divided by the number ¾ inch. Suppose the width of plank at station of strakes required we get ¾ inch or 24⁄32. No. 3 to be 5⁄16 inch, and for the plank at staMark the 7½ inches point 24⁄32. Take station tion No. 15 to be ½ inch. Erect perpendiculars No. 5 as an average least girth section, and at A and G where lines of these lengths cut suppose the semicircle there is a and label the 53⁄8-inch points 3 and space to be 15. Divide the covered at base line into that point. equal spaces, Lay off 53⁄8 and erect perinches on pendiculars as the batten, shown at and divide B,C,D,E, and by the F. A measnumber of urement for strakes res t a t i o n s quired. 5,7,9,11, and Mark this 13 can be take 17⁄32 point off, marked on Figure 12 inch, the the plank, and quotient to lined out. In Page 19 this way the shape of the second edge of the plank is obtained, and the plank given a uniform, fair diminish.1 Of course, it is necessary to sight the batten, when lining out, to detect sudden kinks, and very unusual shapes. Finish the planking, making tight joints in all seams, especially if the boat is to be finished bright. Remove temporary fastening as each plank goes on. Before putting on the sheer strake glue filler pieces between all frames at the clamps. Make them wide enough so they will come up to the sheer line. These are shown at F, Figure 14, and at F, Figure 15. Dress them off flush with frames. The sheer line, or top of side should show a fair line when finished. Turn the hull over. Fit the breast hook. This member is shown at B, Figure 14. Trim the top of the transom to shape, being sure to allow for proper deck camber, and for a rail if one is to be fitted. This is shown at R, Figure 15. Figure 13 Figure 14 Remove the moulds very carefully. It may be necessary to saw cut them at the center line to get them out. Figure 13 shows a “web frame.” The moulds at the mast may be cut away to form a frame such as this, and will add greatly to the strength of the hull at this point, relieving the strain caused by the thrust of the spar. If left in, be sure to provide “limber holes,” shown at L, to allow bilgewater to flow aft. Thomas Darling (1936) Figure 15 Darling’s ingenious geometric methods remind us of an era when computation was slow, and accurate measuring instruments were expensive. Today we have inexpensive electronic calculators and plastic dial calipers, which enable a girth to be measured, divided by an arbitrary number of planks, and that dimension laid out to a hundredth of an inch—Ed. 1 Page 20 Afterword “Miserable Rabbet” I think every boatbuilder has uttered those words, or something worse, at one time or another during the course of a plank-onframe building exercise. I hope in this article to clarify, with the aid of drawings by Charles Farley, this often mysterious topic. The word “rabbet” is a corruption of the word “rebate,” and refers to the notch or open groove that is set into a keel to receive the lowest course of planking. The drawing below shows a typical rabbet and its associated terminology from the front, and that to right shows it from the side. The bearding line is the top, outer edge of the rabbet and the the rabbet line ins the bottom, inner edge. As a builder, you are typically working from a set of lines plans that shows only the external form of the hull, and have to determine the structure, or scantlings, on your own. The shape of the rabbet at any station is determined by the following factors: Page 21 1.The shape of the section, which comes to you from the hull designer. 2.The depth of the keel at the section, which you decide based on the size of the boat and your judgement on strength vs. weight. 3.The width of the keel at the section. This is determined by 1. and 2. above. The keel does not need to extend all the way across but can be narrower as shown to save weight. This is shown as dimension a in the diagram below. Then determine, and draw, the top edge of the keel as shown: 4.The thickness of the planking, shown as dimension b. 5.The desired depth of the rabbet, shown as dimension c. This should be a bit more than one-half the width of the average plank; say, 3⁄8 inch for ½ inch planks. The shape of the rabbet, and the location of the rabbet and bearding lines for each section is laid out on the drawing board. It is not necessary to plot out every section; every other or every third will do, except at the bow, where things can get tricky. Determine the width of the keel at this point and drop a perpendicular down to your first The first step in plotting the rabbet is to draw a line parallel to, and the thickness of a plank in, from, the outer edge of the section, as shown in the next diagram. Page 22 line. The intersection of these two lines is the point of the bearding line at that section, shown by the arrow. Finally, lay off the depth of the rabbet and draw a line at right angles, like this: The intersection of this line and the outer edge of the section, shown by the arrow, is the location of the rabbet line at that section. The final cross-section of the keel is shown next. This should be used as the basis for a cardboard template. It is not necessary to draw the bearding and rabbet lines on the profile drawing unless this is your first attempt and you want to check your work. You can transfer the locations of the points to the keel and draw the lines as a nice fair curve using a batten. The remaining step is to cut the rabbet. In all the cuts to follow you will be cutting in a curve that is partly along, and partly across the grain of the wood. You want to be cutting “away from the grain,” so that your tool does not dig in and split the wood. If you refer back to Darling’s Figure 1, this means that part A should be cut from right to left from the stem to about the the first hole marked J, and from left to right from the aft end to there. Parts B, C, and D should be cut from left to right. The first cut should be along the rabbet line using an Xacto knife or something similar. Make a cut about 1⁄16 inch deep, in short segments so the grain does not “catch” the knife and cause it to go astray. Then make another cut at an angle inside the rabbet, to form a shoulder to guide the tool used in the next step. The rabbet can then be cut with a chisel or a specialized tool called a “rabbet plane” or “shoulder plane” A couple that I picked up on eBay are shown below. Examples of the upper plane were made by both Stanley and Millers Falls; the Millers Falls versions are just as good and you don’t end up paying the premiums established by the Stanley collectors. The planes are often listed as “funny little plane” or some such, and typically got little use so it’s not hard to find one in good condition. Earl Boebert Two Examples of Rabbet Planes The Model Yacht is published three times a year by the U.S. Vintage Model Yacht Group. Copyright 1998 to 2006 U.S.V.M.Y.G. Reproduction for noncommercial purposes permitted; all other rights reserved. Other copyrights are maintained by the original holders and such material is used here under the fair use provisions of the relevant copyright acts for nonprofit research and educational purposes. 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 Western Vice-President: Dominic Meo, III Midwest Vice-President: Tom Pratt Southeastern Vice-President: Thom Mclaughlin Vintage M Class Coordinator: John Henson Vintage 36 Inch Coordinator: Al Suydam A Class Coordinator: Rod Carr U.K. Coordinator: Graham Reeves Canadian Representative: Doug McMain Historian: Earl Boebert Archivist: Jim Dolan Page 23