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JUNE 1957 YACHT HULL BUILDING An interesting method of planking over built-in-frames demonstrated by Horace Boussy HIS series of pictures shows the construction of an A class yacht by Monsieur Horace Boussy, and is reproduced here for the assistance of the picture the building jig is seen. This is a wellseasoned strip of timber planed absolutely true, to which are fitted jigging fillets accurately positioned at the bulkhead stations. The fillets are merely short lengths of square material screwed in place. The second picture shows the keel and backbone of the boat being offered to the jig; the backbone in this case is sawn from two pieces of timber and joined with a strong shaped centre strip, the garboard piece, which also carries the fin. Note that the fin has cut into the detachable portion and the part to be built into the canoe body. In the third picture the bulkheads have been slipped into position, registering both with the keel and with the jigging fillets to which they are screwed. M. Boussy, in this design, is using built-in bulkheads, and in this instance the centres have been fretted out seen. At this stage the bow and stern blocks have been fitted in ; these occupy the space which is almost impossible to plank and are rebated to receive the planking. Photo 5 shows temporary deck stringers or carlings many builders who wish to try their hand at a planked hull. In the first ————— i tiie aye – 2 er already been shaped and that the deadwood has been to save weight. In the fourth picture, some longitudinal stringers have been added, and these are pinned externally to each bulkhead, and will later be removed as will be 280 TUNE, in place, the purpose of which is to stiffen the crosspieces of the bulkheads which will later become deck beams, and photo 6 gives the clue to the positioning of the external stringers. This method of construction is a little unusual, but very sound; it will be noted that the bulkheads are fairly widely spaced, but view of the hull at this stage; note that the ply ribs have been extended beyond the inwale until the glue is dry, the surplus ends then being trimmed away. You will notice also that the skeg has already been fitted through a slot chiselled in the backbone, and that a piece of wood has been bolted to the that, between each, ribs being cut from thin ply bone and inwales, and the stringers. The ribs the correct contour in The first picture on the have been positioned, these and jointed into the backare secured temporarily to thus automatically assume the intermediary stations. second page shows another deadwood to protect its surface during work. bolts pass up through the keel bolt holes. In the next picture ea Soe planking has started The and Monsieur Boussy once more departs from the usual method, in that his planking starts in the garboards, i.e., next to the backbone. As the strips of planking The vertical pictures show the reach the various stringers, these stringers are – the next plank. nearly completed hull from inside and out; the removed. The centre left-hand pictures show inside view shows clearly the shaped garboard piece further stages in the planking, and the large number which joins the two halves of the backbone through of small G cramps used can be seen in one of these which pass the keel bolts. The last two photographs illustrations. The paper protection prevents the G and the heading photograph show the completed hull cramps from marking the wood, and even if stuck down by surface glue is easily removed before adding with all stringers removed ready for decking. 281 YACHT SPEED ANGLE we TRUE WIND SPEED TO TRUE WIND (rere rarer Cy) avie F eather / j ng es Vs Vt Wee bs) 2 ANGLE OF APPARENT WIND TO COURSE | ee REQUISITE VANE ANGLE : = 4 4},2|5 °33 2 OF APPARENT WIND TO YACHTS COURSE 45° 2 |56 |2ele.6 6 3 [75 °3 Guy Blogg contributes -25 rd 8 4 {9-5 02 2 10 5 Ws e15 2 13°3 6% 14 some thoughts on a subject of interest to all yachtsmen. ® © Mea model yachtsmen would appear to use the same vane feather angle for close windward sailing regardless of the velocity of the true wind or their craft. In this article it is assumed that the yacht is on course 45° to the true wind. On account of drift to lee the yacht will point at least 3° nearer, say 42° to true wind. Therefore the angle between the yacht’s course and the apparent wind direction is greater than the angle between the yacht’s longitudinal axis and her course. If, therefore, the angle between course and the apparent wind were known and if the vane feather was set at this angle relative to the yacht’s longitudinal axis, the apparent wind would strike the lee surface of the feather tending to divert it 3°. 3° would effect about 1° weather helm. On a 45° course the direction of the apparent wind depends entirely on the ratio of the true wind velocity to the yacht’s velocity. If the yacht’s speed is high relative to the wind velocity, then the apparent wind angle to course can be under 30°. On the other hand if the wind is of gale velocity, the yacht’s speed is relatively negligible, and the apparent wind 296 > |O|® angle to course would approach near to 45°. If under this latter condition a yacht’s vane feather were set at an angle (relative to the yacht’s longitudinal axis) much less than 45°, excessive continuous lee helm would be effected until she went into irons. I suggest therefore that under normal sailing conditions the feather angle employed depends essentially on Vt Vs_ (True wind velocity) (ship’s velocity) A graph is appended which shows the apparent wind angle to course for ratio values of Vt between 2 and 62. Vs In his book entitled “Model Racing Yachts” the late Mr. Denis Browne stated that “A” class model Ranger (U.S.A.) did 2.94 knots (closehauled) in a 6 knot wind, in which case Vs Vt 2.94 pean 49 rected According to my graph, the apparent wind to course was therefore about 304°. Maybe her vane was at this angle? MODEL MAKER Little Portugal Cup EASTER “A” BOATS AT THE RICK POND NEW trophy in the model yacht world is the “Little Portugal Cup” presented by Senor J. P. de Freitas of Portugal. The competition is for International A class boats, and is limited to crews who have never won the A class Championship or the Y.M. Cup. The first race for this splendid trophy was staged by the Y.M.6-m.O.A. at the Rick Pond on Easter Sunday and Monday, April 21st and 22nd. Twelve entries were received from nine clubs and, at the wish of the donor, the Portuguese Embassador, Senor P. T. Pereira, G.C.V.O., was invited to start the race, and Some idea of the cold and condiwet tions on the Monday can be gleaned the from above photo, taken when the weather had improved! A this His Excellency kindly agreed to do. little ceremony of welcome took place on Easter Sunday morning, Below, Serica sailing full and bye in the Sunday sunshine. Skipper Norman Hatfield, arms akimbo, is on left of group in second eam which also includes, |. to r., Major R. Alston (Chair- man, Y.M.6m.0.A.), H.E. the Fostuguese Ambassador, O Poke cal ee yl went airman, (0.0.5), J. Anderton, A.), W. J. Daniels T. L. Harris (starter) and A. Hill. Opposite page: Red Sabre leads from Charm, Roberta ahead of Juanita, and Fill well in front of Baritka 304 during which the Ambassador signed the visitors’ book, and addresses of welcome were made to him, both on behalf of the club and the M.Y.A. It is of interest to note that the Ambassador is a sailing enthusiast and is in fact the owner of the schooner Bellatrix which took part in the 1956 Torbay-Lisbon Race. His Excellency was most impressed by everything he saw in the clubhouse, and was particularly pleased to meet Arthur Levison whose name was wellknown to him through the figurehead for the Cutty Sark, recently completed by Arthur. The Ambassador started the first pair of boats at 11.15 and the day’s sailing got under JUNE, way. The wind being light and variable excellent sailing was seen and there were several very close finishes. With all boats very from the S.E. gave a reach both ways on the water, and scores were therefore two close on points every point counted, and it was obvious that any of four or five boats could win. Three heats were sailed before lunch and the final heat and resails took place in the afternoon. In the last heat Serica met Ombamijoy in one of the greatest tussles of the whole meeting and lost both ways, on the windward board by only about six inches. This left her needing to win a leeward resail against (Continued on page 303) points for each board. Three heats were completed by lunchtime and a freshening wind with more south in it enabled spinnakers to be used in the afternoon; under these conditions four more heats and the resails were run off by 4.30, at which point Serica and Arabesque were leading, tying with 20 points each. Monday proved very different from the weather point of view, racing being resumed at 11 a.m. in heavy rain and a very light and variable easterly wind. By lunchtime the rain had become intermittent and after lunch the wind freshened slightly, backing to N.E., giving a quartering run The Ist conditions SERICA out and close fetch back. were very tricky, but some 750 * N.D. Hatfield… … OMBAMIJOY 404 L. W. Wareham … London JUANITA 720 J. G. Meir … Birmingham … 4th JILL 716 A. Levison … Guildford 5th SHARMA 541 W. G. V. Blogg… . Y.M.6-m.0.A. 284 J. F. Thorner 2. Y.M.6-m.0.A. 5th ARABESQUE 671 S. E. Marden .. MLY.S.A. CIRCE 293 P. J. Leigh Ale Landon 9th RED SABRE 704 G. Kirtley and H. E. Andrews Newcastle ROBERTA 707 A. Davis … S <3 S 2. Zz O 4 83 ean C ... Bournville yee QP eenOr yes (AN 2s 0) 42 2a. Mee 463 A. F. Kind 2. Sauchan’ Seay, 476 C. M. Smith 1. S.. London ore 16 16 4-7 .9, OO eSB: 16 20 20 Se S68 Oo:
