The Model Craftsman: Volume 8, Issue 1 – June 1939

WHY RATING RULES? News of the Clubs By C. O. BROOK By H. B. TUCKER ITH the X Class model tabled for conservative. There are more than that L.O.A., 48” L.W.L., 11” Beam, 12” Draft, 25 pounds displacement, unlimited In this Club, especially when we attain the future, Dr. Houk of the Seattle M.Y.C. proposes an “S” Class.—60” sail area, spars, etc. Next thing you know, I’ll suggest a class—and boy what a humdinger that will be. But the boys are interested—-and how! The new Year Book is a honey. Congratulations, Charley Farley—it’s a nice job. Those who may have been skeptical in the past as to the growth of the sport certainly should have their doubts removed after reading this handsome book. The Deeper Hudson M.Y.C. had a dis play at the Albany Industrial and Sports: man’s show and starting with only twenty- four hours notice, and 100 square feet of space, we ended the first day with 400 feet of space donated and by the close of the show were credited with having the most attractive display in the building. And now, unless the Gods of Fate will otherwise, we’ll have a clubhouse of our own before our Regatta on August fifth sixth. And that, Gentlemen (and Ladies), will be a house warming—and a heart warmer—to you and to us. Gosh, how the challenges and invita- and tions do fill the mails these days. We were intrigued by one from the new Nassau M.Y.C. on Long Island. It was a “pip” with the most nocturnal heavenly blue cellophane we have ever seen. We long for sails of such beauty—what a “cute” ship “twould make, draped so. If the Nassau boys will only take the hint, now—! When we note the cost of some of the Club Houses being lean over erected backwards to we begin see top of the price really is. where to the When they build ‘em for 55,000 real dollars and go even as high as $70,000—-Gentlemen— that’s building. There registered should for June, 1939 be at least 1939—and 1000 models that figure is amount of models used—Why not sup- port the sport and Register your model? our home, we plan a “science forum”. Any modelman who has ideas, or wants ideas may feel free to write. We will try to answer them both personally and thru these pages. If we get the co-operation we hope for, we will have suitable tanks and equipment to make experiments so far as our limited ability permits. We might be able to furnish drawings for these pages in some instances. If you have something that can be used as it—send your data along. And may I suggest, that, granting you wish these columns to continue, you send me such club news as you may have. No writer can make reports that do noc exist—and this should in no way prevent sending news to other sources that might (Reprinted from the 1939 Year Book, Model Yacht Racing Association of America) Let us consider why rating rules are necessary. Mr. X builds a boat, say, 48 in. long, but his rival, Mr. Y, takes the same design and builds a boat 60 in. long. Both boats are equally good, but Mr. Y always wins owing to larger size. As this kind of competition does not produce close racing, some sort of classification is neces: sary. Length Over All is taken in the Marblehead, 36 in. and 30 in. Restricted Classes. The natural result of taking L. O. A. is that overhangs become very short or nonexistent, since the length that counts for speed is sailing length and overhangs only come into play as the yacht’s speed increases. In the 10 rater Class, Load Water Line length is measured, and the result of this is to force designers to get as much that the job was GIVEN to me to build unmeasured length as possible by means of long overhangs, so that the L. W. L becomes very little check on L. O. A. Now, up to a point, overhangs are of great benefit to a yacht, since they provide reserve buoyancy, tend to check pitching, and provide additional sailing length. When the overhangs get too long, they slam in a seaway, making a wet, unsea- capacity. be cut off short, except for the fact that it enables the designer to carry out his lines be your personal hobby. These pages reach many individuals whom you cannot reach in any other way. And to set the minds at rest, of those numbers who ask what recompense I receive for these col- umns, or for sending out an average of 600 letters each year, I can only state the sport in my small way. This is my way, with the help of this magazine and the mails and there is only the personal gain of finding new friends—monetary remunerations are not “enjoyed” by any Officials of the sport, no matter their I hear from John Black that he has Bostonia 7 ready and will sail in the Eastern A Class Championship event at Port Washington, N. Y., May 27-28-29. I’ll be there John— I hope—3 days of good racing with the “A’s” certainly ap- peal to me. If John’s No. 7 is as good as his No. 5 he’ll make tough competition for all hands. Wonder what Bithell will have? We will stick to Sea Fawn 4—she’s a grand old next issue. tub. And that’s chat—’til worthy type of craft. Moreover, it must be remembered that overhangs are useful just up to the point they become immersed when the yacht is on the maximum sailing length. Beyond this, they might as well to their logical conclusion. In the “A” Class Rule, the Quarter Beam Length and in the I.Y.R.U. Rule, (6 Meter and 12 Meter) the girth of the overhangs is taken into account. Both of these systems have their supporters. Each has its advantages and disadvantages, but there is not much to choose between them. Both produce a fine type of hull. Displacement weight. Weight, means in (Continued on bulk itself, well as provided as as page 60) (— PLANS pret (Continued from page 27) high a proportion as possible is in the FOR THE MODEL RAILROADER INED TRAIN. Fu #2—UNION PACIFIC STREAML size blueprint. 4%” scale …–++eersereerers $1.00 50 #4—P.R.R, STEEL CABOOSE. O-gauge ……++ NED #5—PHILADELPHIA & WESTERN STREAMLI 80 TROLLEY %4” scale. The car that made 50 M.P.H. and passed up the trains CAR, #7—AUTOMOBILE New R. R. Central York #16—5-STALL ROUNDHOUSE, O gauge layout of a prominent model cluD …-.-.-seeeeseeeeees « 1.00 O#17—C.N.R. two unit GAS-ELECTRIC TRAIN. 1.00 gauge. Will run around 24” radius …….. State #18—S.P.R.R. 60’ BAGGAGE-MAIL CAR. Either type, full whether for 4 or 6 wheel trucks. BIRD. sh. cwiccinwsrsceiarecrarwcivieiessieieieiwiee se9:6i4:9.8:5:0,016 8:0’8 1.00 Wheel bottom CAR TRUCKS—6_ #24—PASSENGER type CAR FREIGHT equalized. Commonwealth one sheet. Full size drawings ………++-++ TRUCKS—6 wheel equalized. Buckeye type. Both O-gauge, fully sprung and equalized. Two on .50 eee messes e ree ses eee essressseseesrese #26—HOPPER ORE CAR. Car 6” long over bumpers. Full size @-gauge drawings gs …….. a aialsantesae 25 SEMAPHORE SIGNAL, O-gauge. Type used on leading lines ……0.+6+ ee weWieies’e4 . 29 #29—PASSENGER CAR TRUCKS, 4 wheel, bottom #28—38-ARM equalizer, fully sprung GAUGE #30—NARROW +25 sevens …….–eeeeeee LOCOMOTIVE. Ten sheets, gauge. 2%” are some scale, 1%” size and full SOME Are IATZET ….. ee cerevececesereeessecs 5.00 #33—4-WHEEL CABOOSE, O-gauge. 1890 type . .50 “Type E8s Cla #34—‘‘O”” Heavy Switcher—0-8-0. OC CSCO ODS 1.00 siviesersicnisrenwere RETA (3 QHSGE)) #35—35’ 8” Stock Car (7100-7134) #37—D. L. & W. teel Flat ton Hop- 50 (2000-2051) #40—Steel V. F. Caboose, #41—Composite Gondola | RON 50 -50 Car (88000-88399) and ……ccceccecccecscees 4-wheel Caboose ………….. per Car (6100-62999) OC OOOO COCO and Steel Goode 8-wheel ……….se0s -50 Car and Steel Gondola OM ODO OOO CUO COC ICT Cnc FOR THE MODEL SHIPBUILDER and sail plan. 2 sheets #8—MASTS, SPARS & #9—RACING ICE YACHT. Full size blueprints for full 5 rigg ship with list of spars and ropes ………-. 1.00 and sail plan. #105—29″ model 2 sheets RACING Racing SLOOP. Yachts. Complete working details ………. eeewawereae: 2500 Full Winner size of plans 30” …… #12—50/800. MARBLEHEAD, CLASS RACING YACHT. Latest design from Sail plan x 10”. the Board of Naval & full size drawing #13—RACING Architects. ……….s00. 2.50 MODEL HYDROPLANE, Class C, Full size lines & frame sections #14—BALSA RACING HYDROPLANE, Full size lines and sections Class 27” …. 1.00 D, 21”. ………….e0e8 75 #18S—“CITY OF NEW YORK.” Full size plans, scale a to a foot. Spars, rigging, lines, sections, levations and sail plan …..-.seeeeeeees ee. 1.00 #2I—HARBOR TUG. 17” electric model. MOOK: TRAN: ANGIRARG 8/16” scale or full size for Lines, sections, elevation sos eeiccecncciwciniewlawicinesieeis and 1.00 #22—STEAM TRAWLER, %” scale. Size 13”. Completed lines, cross sections, elevation, deck plan and details ….ccccces 9.019,0:0.0.0010.0.0:9. 0.5 .08.6 8,0 cen .@ drive a 60” plane or 24” speed Scat’ Full size #23—AERO ENGINE %” x 5%”. Getail drawings Weight 9 ozs. Will ……….c.cceccee ences wate one #31—32” CABIN CRUISER. Round-bottom type. Full size drawings with cross sections and cabin arFANECCAONG: isjc:sieieiw’s:0r0.ci ere pwienieuaieiene-ciee meses – 2.50 #32—39″” RACING HYDROPLANE. Latest type. Class “A” and “‘B’’. Full size ……….. seccccos 1.80 #34—10” OUTBOARD RUNABOUT. Easy to build 1.00 Handy workshop #27—EARLY and TOOL combination CHEST combined. -50 An original Con- Top 20” x 2414”. 2 sheets with …………-.-. eee eee ee eee -25 DEPT P-639 60 the maximum efficiency on any given area. It is also important for the sail power to be proportionate to the hull. Too much sail can be as bad as too little. The factors producing speed are length, sail area, and up to a certain point, displacement. Of these, length is a linear measurement. Sail Area, a square meas- urement, and displacement a cubic meas’ urement. In order to reduce these to a common denominator for the purpose of comparison, one takes the square root of the S. A. and the cube root of the Displacement. Any factors, other than the three mentioned above, that appear in rating formuJae are introduced for the purpose of influencing the type of boat produced. The simplest formula in use is the Length and Sail Area Rule which is:— Mt. Vernon, N. Y. of a restriction in the shape of a sliding scale based on the actual LWL, not the Length taken for measurement. In the Avclass rule, all three of the speed factors figure in the actual formula. In this rule, sail is given for displacement between certain fixed limits on a sliding scale, based on the actual L.W.L., not the length taken for calculation of rating. There is no penalty for exceeding the up- ward limit of the displacement allowed, but no additional sail is gained by doing so. Lighter displacement is penalized by deducting the amount of the deficit from the actual cube root. In other words the designer suffers to the extent of twice the deficit. The lower limit is set rather high —many think too high—under the rule, but actually the bottom displacement limit boat has the highest sail-weight ratio and heavier boats, though they get more actual sail, have a decreasing sail-weight ratio. In this rule Freeboard does not figure in the formula, but is the subject of a restriction, and any deficit is heavily penalized. Under both of these rules certain minor dimensions, such. as height of sail plan, are limited. One of the main differences between a Restricted Class and one governed by a measurement formula is that in the Re- stricted class no single dimension must ex- of the sail area must be taken to bring the different factors to a common de- ceed the appointed limit, but under a measurement formula an increase on one dimension can be compensated for by a decrease in another. Thus a boat having a little extra length can usually be brought into rating by cutting down the sail somewhat. Thus it will be seen that it would be unwise to limit LWL, since a very slight miscalculation on the part of the designer or builder, might put a boat hopelessly out of rating. factory, though excellent for models, The bers of “‘one-designTM classes. These are classes of identical yachts, built to the same design and specification in every Lx &. A, = Rating 6000 In this formula L is the L.W.L. and It will be observed that this rule directly transgresses the axiom laid down above that S.A. is taken in square inches. nominator. The rule was, however, promulgated 30 years ago for full-sized yachts, and, in the end, proved unsatis- novice may ask why, if the rule remains satisfactory for models, it proved unsatisfactory for full-sized yachts. The reason is, of course, that a model sailor is not aboard his craft. The 10-rater is the only class now used under this rule. Note the divisor 6000. Any fixed divisor or multiplier in a rating formula is known as a “constant.” It does not change for differ- ent boats but applies to all boats rated under the rule. In addition to the different methods of measuring the length (both of which influence the type of boat), there are several notable differences between the LY.R.U. and A Class rules. In the I.Y.R.U. rule, length and 5.A. are taken into account in the actual formula. In The first of these is the factor “d” which is the difference between Model Craftsman Pub. Corp. 23 E, 2nd St. fore, important for the designer to provide introduced. …………-.. AMERICAN TABLE. necticut design. full imstructions Sail is driving power, and it is, there addition to these, other factors directly influencing the type of boat produced are FOR THE HOME WORKSHOP #6—WORKBENCH proper speed. for comparison purposes the square root ………eeeeeeesene RIGGING form of ballast well below the water line, gives the power to carry sail. Weight also enables a yacht to hold her way through calm patches, and, once the inertia is overcome, gives momentum, It is, therefore, a factor giving speed, always provided the weight is not too great for the sailplan to set in motion and bring to its * #43—Steel underframe (10000-10999) and Composite Box Car (14900-14499) ……ccccccccccccccce -50 #3—20-RATER MODEL YACHT. placement is insisted on. This is not included in the formula, but is the subject MODEL YACHTING the actual skin girth and the chain girth. The effect of this is to discourage a hollow garboard. The second factor “f” is the average freeboard, and, as this is introduced as the minus factor, it encourages the designer to give his boat a generous amount of freeboard. Displacement is sternly regulated under the LY.R.U. rule, and a minimum dis- In full-sized yachts there are great num- respect. The object of these classes is to provide racing without handicap at a moderate price, without the possibility of boats being outbuilt by more recent vessels. In many it is a stipulation that all the boats are built at the same yard. As one set of moulds does for all the boats this is an economy, and further ensures the uniformity of the yachts. It is impossible to have one-design model classes since so many models are built by amateurs and their productions vary so much. Further, it is undesirable, since one of the objects of model yachting, is to make progress in design and building. It is hoped that these remarks may help the novice yachts are to rated understand why as they are. model He may, however, well ask himself why the pundits who propound our rating rules should concern themselves with influencing our models to produce a so-called “healthy” type of craft, since all that is required of a racing model is to sail fast and handle well. If he is of this opinion, he may well ask why do we not adopt a simple classification by sail area, as is done in certain model and full-sized classes on the Continent. This leaves the designer to develop the fastest hull possible capable of being propelled by a given power. IVhen writing to advertisers please mention Monet CrartsMAN for June, 1939