How to Design a Yacht by Charles G. Davis – 1906

HOW TO A DESIGN: YACHT. -Bin CHARLES G. DAVIS. NEW YORK & LONDON THE RUDDER PUBLISHING CO 1906. COPYRIGHT 1606 ay CHARLES W G, DAVIS YORK Rights Reserved) FROM THE PRESS THOMSON CO. IMURRAY ST. N.Y.CITY INTRODUCTION HE art of designing vessels—that is, of drawing their forms upon paper—is old, much older than most people suppose. ments of the art can he acquire in a hundred technical schools. It is more than probable, although we have no records to show it, that the ancients so delineated ix_craft Ac early ac the Fifteenth Century it was In the early days, a few books dealing with ship de- signing and construction extremely eri Lawine were published, but they are to the ene: fon: ERRATA Page 13. Table of Offsets, Raceabout, Section 8 should read 1-6-7. Page 30. sixth should Fifth paragraph should read: cubic feet of water; paragraph read: read: 20x 8 should read: 2x2x1=4 cubic cubic 2 = 320 cubic ft.; ft.; ft. seventh eighth paragraph paragraph should ninth paragraph should read: 35.X 14.5 X 3= 1522 cubic ft.; 46.2x 15 x7 = 51097 cubic ft. Top line should read: “only 435 cubic it., or 28% second paragraph should read : Her length x breadth x depth gave 5197 cubic ft., but she only occupied 1212% of this, or 645 cubic ft.” The result has been a constant and generous advance- know and what he cannot find out in any other treatise on ment of the art. designing. To-day, vi igning, instead of being the property of a few, its practice carried on behind locked doors, is the p sion of the many, and the rudi- It is for such persons, those who take up the art for amusement and not as profession, this book is intended. Eprtor. INTRODUCTION HE art of designing vessels—that is, of drawing their forms upon paper—is old, much older than most people suppose. ments of the art can be acquire! in a hundred technical schools. It is more than probable, although we In the early days, a few books dealing with ship de- have no records to show it, that the ancients so delineated signing and construction were published, but they are their craft. extremely As early as the Fifteenth Century it was crude, and owing to the expense of engraving the practice of shipwrights to lay down plans of vessels, but very sparsely illustrated. and a large number of such designs are in existence. br two designs given. Many of these are of very fine vessels, and are excellently at present, was first begtin about sixty years ago in Enz- drawn. land; a small book was published on the subject by a It is probable that tke art, as we know it to-day, Usually there is only one Yacht designing, as we have it originated in Italy, possibly in Venice or Genoa, cities man named whose shipwrights were the most advanced of any in the text-book. world at that time. by the late Dixon Kemp, which is to-day the leading work of drawings teenth There is to be seen a splendid series made by an Century, -showing Englishman some in remarkably the Six- Marett. is was for years the standard The next work of importance was that written upon the art. fine-lined But all these books are written high over the head of the average man, and are intended for professional galley One reason that the art of designing is supposed to be consumption. The writer, himself thoroughly compre- recently modern, is due to the jealous care with which its bending the subject, cannot get down to the simplicity of methods were concealed by those who understood the explanation that is necessary to the beginner, who is science. totally ignorant of even the first rudiments. Like the religious secrets of the Egyptian priests, For years it was shrouded in the darkness of oath-imposed secrecy I have endeayored to get somebody to write a Yacht- and handed down from father to son, or from master Designing to apprentice. AS BC. Except in rare cases, the designs were never allowed to be published. This practice continued to alate day, and is still kept up by some designers. more liberal and progressive body of men But a gradually Primer, that would start off teaching the I know of no man who is more capable of doing what is wanted than the author of this book ; he, more than any man, understands what is needed, and has the power of explaining intricate and profound practices in worked into the business, and casting aside the old and extremely simple language. selfish practices, gave freely to the world their labors. he comprehends what is necessary for the beginner to The result has been a constant and generous advance- know and what he cannot find out in any other treatise on ment of the art. designing. To-day, vessel designing, instead of Being largely self-taught, being the property of a few, its practice carried on behind It is for such persons, those who take up the art for locked doors, is the possession of the many, and the rudi- amusement and not as profession, this book is intended. Eprror. TABLE OF CONTENTS. be Desiqgnin 24 Table of off sets 30 ‘Calculations 36 Models 39 Dories 37 Pamlico Sound Beals 42 Cutter Pup A5 Schooner VIRGINIA 47 Schooner KATHLEEN 44 Sloop DRAGOON 52 Sloop ReoBank Y.C. 53 Sloop MONSOON 55 Yawl 57 Ketch 59 Sloop 63 Sloop 66 67 Yaw! Sloop 61 Sloop TAMERLANE KisHIMA GAUNTLET NAIAD Freya ALcaToRDA GENESEE 697 7! Sloop Nimeus-ttl. Sloop N-RY.C. 17 74 30 Gat Naw Cat CAMILLA BB Cat 75 Cat-Yawl KUMA RAMBLER Poco Haight Force a Orns g4 Rowboat VORANT-l $2 Slop » 6% Rowboat 10 FOOT 11 FOOT %5 Sail Plan 4% Diagram of cal rig. 89 Diagram of sloop “19 qo Diagram of yawt ng 4! Sail Plan o f Pur q2 = » AS qu KATHLEEN GENESEE NAIAD TAMERLANE qs ALCATORDA Gb FREYJA 91 “qe » GAUNTLET 100 101 » NIMBUS-III » DRAGOON « KISHIMA q4 102 103 ~ VORANT=IL ow KUMA . » RAMBLER Ge eur 104 105 : r “ “i 107 . “ 1o% m i lob : « NRG. * RBYC . DORY. DESIGNING. Let -us suppose yow want To build a certain kind ofa yacht and havent the time To do the work of constructing the boat yoursel. ‘To 30 clvaw out the plans that a boat builder may take them and build ~ 1891. naval- architect? work to Even her for you is evidently guile an art It is the yaeht-designers’ or as some call them elves, prepare such if you are going to plans. build her your self if is the only correet way To qe about it. Years 490 when every thing was built by “tule -3-thumb” “and only the simplest kind of calculations were made, the builder used fo whittle a model of the purposed craft, mark out her outline and enlarge it to full sige to get the shape of her keel, stem, stern,clé. Then saw the model up info several sections to get the shape of the boat at intervals along her length, Do, when the ~ keel was set up, = ae he could $ef.en- ie Sea a eas larged moulds made from these small patterns at their proper distances along the Keel. Then hy bending strips of wood called ribhands, from bow te slemn around these moulds he could fit in timbers at any intermediate posilion desjred. That kind of worl is all right if,as it was in those days ,every was built from one conventional model, the proportions only beng changed. All boats were then built on a4 straight – stie kk stem and stern post set To a boat cerlain angle and for a keel, ana others for one mid-ship section would answer for nearly all boats, but Today there are as many different shaped yachts as there are men owning them. Though every model may be different the operdlion of designing is the same- the rules for figuring the various elements necessary To de- eide the actions builFare all of the based. on- DESIGNING -On one set of rules and 2. are jusas t posilive as any rules in arithmetic. The only variable element that enters into the work is the matt er of personal experience, whic h ; is different with every person and 5e long as Qmeriecans Qmericg Dutch and in live always will in the Holland. Nine-tenths of designing 13 A a “ ri matter of judg ment Eee and ex perience. “In For instance ,one of the : your first Shall first boat is she be «a ce?” quesTions be, thaT avise when – “What 3i9¢ shall she be?” Holland” 70% decide Others to Aesian immediately follow. center-board, keal, or fin-keel boat?” .”What beam, Araught, We will assume you have looked over enovah beats and measured several that were of just close to your ideal, so that you hav e the siz@0 and an idea the kind of a boat you want Wn out flat on a drawing boarA of paper of draw your such yacht on feet lwo intention to your. sheet mind. 8i9e as will enable you To large meaoure accurately from. our a fixed in enough Beats Treat on, a seale te such as it is vi3!- under fifty water line, can be drawn on either of scales, as follows, up te thir ly feet water-line on feet on With one-inch scale half-inch over thirly seale. your tee rule on the left edge of the drawing board, dvaw a horizo ntal hne blue in ink to vepresent the water level. hetween if Leaving and voom the Top yoom for the boat above or five inches. A Designer’s Corner: of the water, paper to say about give four DESIGNING -3. Below this, alittle deeper than you intend the boat to be, draw another line in red ink as a base line to measure 16. It is better To always draw the base fine below the keel a little, as all boats have to be blocked up off the ground a short distance, and this puls your base-line so there is a space for these blocks. Below the base-line draw another red line as a center line for the deck or halt breadth plan a little more than half the width of your boat below the base-line. Tn merchant ships the length as measured for | al i tonnage js the distance from the forward side at of planking on the. stem to the after side of the Space stern-post This distance is Termed “between perpendiculars} but in yachts where the length measurement is usuall for TITLE 2 Raper ruled for plans. taken on the water line this really becomes the distance between which the desiqner is To work. So allowing space for the after overhang at the left edge of your paper square up a fine red-ink line for the after jer- endicular ana the length of your water-line away to the right of it, measured of course by the seale To whith yow are designing the. boat, square up another red ink hne. It is usual, although not by any means necessary To design yachts with their hows always pointing wn one direction principally se that comparisons may be made between two designs. Most boats are designed urth their bows on the right. To the right of these plans leave paper enough to draw the shape With yow are the boat end the center-line, base-line, waler-line and perpen dieulars, ready to test of judgment “How to the on. begin the real designing- here comes the first , backed ly experience. much freeboard shall be allowed from the wafer-line sheer line ?” Let us look into the question. There is no iron-bound rule or law that says how uae or how little free board you shall have, unless you are desiqninga racer q for some ouch organiyation DESIGNING or club as 4. The Massachusetts Yacht (acing Association, where a minimum rules. — freeboard This is i5 a ver slated por each class of koats ood thing, as if prevents kuilding a@ racer so low-sided that she would be a wet, unsatisfactory dlinary boat for or- use. Outside in their of such clubs this freeboard question is left por your own decision. Narrow keel craft usually have more freeboard than the widecenter board omall boats. bodies Boats intended of waler need yough ocean work. foe for use on the Great South Bay or less freeboard than those intended for The Cape cals, for instance, ee are very high- sided; and eer all cruisers, as a A River Tow-boat Pees es rule, have ae more height out of An Ocean Trame. water than the racers, as the latter want to expose as little surface as pooitie to the wind on account of the resistance if produces, also weight of the topsides. has of his head above reehoarA on GQ swimmer she unnecessary swims easier the less he water– but then the cruiser as the slays that asa rule send the racer seurrying again you want good out and for home as the sailing necessary To complete the rece is over. the Scuppers on usually leaves the shio when green rides water gots seas s00n as Comfort washing along deek. Q set of proportions showing the relative height of freeboard compared to the beam of various kinds of kvats is qiven in the following Table .- This gives from vst the whieh you the data to decide the question that arises, least freeboard. + = Old Whalers New Bedsord July 2-189. DESIGNING — 5. TABLE GIVING FOR South Bay Cats PROPORTION OF FIREEBOARD TO BEAM. VARIOUS KINDS OF YACHTS. ( for shallow water) about 20° w.l. Freeboard (least) is Ya the beam Lil. Sound Cats (for general use) about 20! wi. fe do’ wil. Cape Cod Cats (for ocean work) 25 Sloops Small Vawls (for general use) 25 te 30′ wl. about 25′ wl. 25% 50′ wl. Large Yawls 46% 50’ wel. Schooners “7 heice s fs : fe Veta Vern & «Viet V5» © Ye ri . : nee Vere » Vets Yor.» “But where, in the distance between the two red perpendiculars shall this point of least freeboard be?” “What shape shall the line, represeriling the edge of the deck at the side, assume fore and aft?” This line is known to sailovs as the sheer line. In ancient times the stern of the ship was always the higher. as is illustrated in the””Arab dhow’, ‘Chinese junk, Malay felucea , old Spanish galleons, and even in our own old Time ships. Ships of all ages where it was a hand-to-hand warfare on deck have the stern, the end where the officers live, much higher than the when the enemy bows. This really secured a was the fort into which, foot hold on their deck , the officers and crew retreated, and from this elevation over the enemy on the lower, forw eh AN Mf ine 5 Relics had an advantage 1 é- \\ of the idea that the stern should be the highest, are to be found in the old Hudson River brick- sloops and schooners. DESIGNING ~ 6. | A dly a craft is built now-a-days but what this condition In fact the modern yacht is eot point of her better- looking with sheer about 1s the low- ‘fo of her water line forward of the after perpendicular. The rougher the water the yacht is intended to sail in the higher in proporfion to the Boats for very smooth how to the sheer water need little or no sheer and ean be very low forward, but a fair amount of sheer always makes a hetlee- looking eraft. It is like ueslion. a yacht by her sheer. oteam yacht stands out clear of be reeognijed by the straightness of his In sailing yachts there is the’ same distinctions ;- the deaiqner used higher hand wriling, this sheer the fleet about her *Y the sweet proportions of her sheer.and ends. Just as one Amer- jean designer’s work ean who mans “You ean almost tell who designed A Watson The, Gloucestes Pabermae sheer. a an than are the of a circle for his sheer only of course the bow is stern and this throws his least. freeboard just a litte aft of the middle of the water- line length. ‘The man who uses a section of a a parabola ~ beginning very straight forward and gradually inereasing in curvature towards the stern,and the man quile straight along and last, but not the middle down with a quickening least, for there are altogether the man who designs to hamp who makes at the a after he carries it out flat aft. Saami bh ~~ 2 ee a 4 sheer that end when like qa his sheer line curve. at each end, too many built into such examples, wood appears broken-baeked, boat because Now each one of these sheers are fit fora certain kind of a yaeht.except the last, anal that ta faulty,ao | will explain in its turn. DESIGNING — 7 No-l. The are sheer, is all right on wide models where the side line is also much on the are shape, Suchas the old style sand- bag cats and sloops and most of the CGmerican center -board boats that were built before long ends came into vogue. No-2. The parabolic sheer is the prettiest and hest; it keeps the forward part of the boat higher above the water, and the graceful up curl at the after end gives aspring and jightness to the after overhang. sheer for everything but a very wide boat. No-3, Tf the boat has This 1s the best a parallel shape with short ends the third sheer is best, such as On a canoe | you have heen observant or canal-boat. and used your bram you may have noticed that there hasto be acertain likeness hetween the sheer and side or half. breadth shape Qn ave sheer takes an are side line , a parabolic sheer takes a similar side lime, a straight sheer with a eurl up at each end fits a boat whose side line is long and straight with bluff ends. No-4. [8 what the boat will look like if the sheer be an are and the stern pinched in quickly. The one line influences the other, with the result shown in the diagram. Such a vesult means No-A. should have had move A few examples of various assistance to the novice. pendiculars into you have ,counting such sheer aff. sheer lines may here be of some By dividing the distance between ten equal parts and drawing vertical red ink lines the forward jeerpendicular as number one -eleven lines- By measuring up on these lines following dimensions the different sheers Boat Keel dloop_| per- Designer. Wi Gardner. of 2-4-0) Roeeabout | B.B.Crowninshield |/-//-0) Cat Boat | W:1- Force 2-3-4 Fin Keel 2-4-1 Chas.Olmsted 2\3 PF from the LW. the can aA 7. be reproduced. &\ 9 |\72\| 1-6-0) 1-5-7) 1-8 167 “7 DESIGNING: 3. The heights of bow and stern are \argely matters of personal judqment, rather than any fixed rule and qive that individuality which enables you To identify her with a certain te a boat designer. “Measure off as much overhang a> you want your boat to have at each end, the after over hang usually being a little fonger than the forward one, and sketch jn such a shape bow and stern as your fancy clie- tates, Every one who is intevested enough \n the subject of to yacht clesigning go to this extent, is sure to have some decided ideas about boats, now is the time te advanee them. From the simple litte plumla-ended eat-boat To the elaborate steam yaeht there is a certaim of proportions and angles harmony a fov each that ean make. a complete- looking, tidy Itle evaft, or a great, ugly looking, un finished ap- pearing one. Styles appear and dis- appear. in yacht building as ‘in avery thing else, and 30 always aim to turn outa atylish , up-To -date beat. Dut do not sacrifice the utility of the yacht for the purpose for whieh she is intended , To style. With the sheer and stern part \s want overhangs settled. sketehed in all the and bow above water sy Dragoon Then decide on the draught of wafer you her to have and sketch in an outline it: of the bottom of the keel. DESIGNING ~ 9. l; she is te be a keel boat , remember what difficulties are liable to be met with, such 4s elling aground, unhandines in hauling out to pat or lay up for the winter, ele.,and fry and overeome them. The Buttereup-” Enough keel for the boat te sland on in ease she should get aground 1s aqood point to remember, and the angle of- that keel on the bottom such that the yaeht will not pifeh-pole head first and go bows under as the tide leaves her. Clso, remember, the keel has t go through the waler as fast as the hull, and dont get boat sluggish in if so dragging large in area asto make the it. 5 The rake of a Sell opal and forefoot next take our consideralion;. but the y novice had better draw them to suit his eye antil he SG f subjeeT of yacht construction, plicated that nine-tenths of The two ofudies they , | form , leaving it fo move prac- the impossibilities XY \ which is so eom- if its study entirely alone and \ the amateurs, )eave merely I ois turn out. design a Tical heads to build tie adelaide -1908. should go hand to know whether if is’ possible 1 has faken up that in hand,as iV is just as important build a certain Shape as it is to know how to draw that shape Often a builder sees changes that eould be made that would not alter the boats shape any but would save the owner many dollars, just because the designer lacked joraclical ex pevience. With the profile nous complete the hale width of the boat comes aert. The amount of beam she shall have, and how guickly or slowly that beam shall diminish towards the ends. “Beam”, as | myself ae often remarked, “never hurt any vessel” But too much draught often has. used as q light- ship or a that the move lulk there is If a vessel weve fo be spar-buoy To ride still on the water , jt is obvious deep down under water the less there. \s above water To pitch about. But boats being intended to move through the water, meet with qreat resistance if their bulk fo their length {5 cavried very deep in proportion ye CiTy ISLANO7 —— 1S. 4° 194% — Jan DESIGNING — 10. Te form an idea | – oil Tank, A Whale back of about what beam should be used on clifferent of craft @ comparison of the measurements will show that:Cat-boats kinds or shallow water the length is 3 times the beam. water the length is Qtr2/r times the beam. the Length is 33h times the beam. the Lengthis 4 t 5 times the beam. times the beam. the Length io 3h l Cat-boats for rough Center-hoard loops sloop Keel Yawls the Length is dA t4+ times the beam. Schooners For instance, the Lucile is 2! over all and 7′ beam. -~Her length is just Btimes her beam. The Harbinger was 2% overall and 13°©” beam. Poor old Harbinger, I was laid upin bed, had run a nail in my foot that cay, when about nine orlock in the evening the street. the fire hell rang and I could see q I heard the fire engine coming clown glare out of the window in front of’me, over in the Knickerbocker Athletic Zlub grounds at Bergen Pr, Bayonne, Ned., | knew there was no house where | could see the firemen fighting the flames Next day T hobkled over to the beach, and there was the ehavred vernains of what T always looked upon as the best eat-boat ever built. A fire-buq had put kerosene on her and set her afire – He js now in jail. “To resume our designing- [By this rule take the length over all and divide if by the figure given to find the beam, we have the same When the beam is olecided, uestion to decide that the sheer presented. “Where shall be thewidest part?” “How far rom the bow or stern?” Here all ordinary data fails To show the answer and judgment ts required . About ninely per-cent of the yachts are widest in designing ; ships the middle for quite a just aft of the middle. length is of a paratlel shape, likea box with short bow and stern Harbinger after the fire, rounded off on if; this is sa as to gwe as much cargo space as ossible on a qwen length. This flat part is called the “dead – plat’and in designing the shape of the frames: for the bow and stern when they come To this midship Ib. II. DESIGNING – shape they designate it with a mark ,thus – BB, illustrating that this one frame is the shape of the beat along in the middle. Yachts have no ‘dead-flat; the beauty of the yacht model waula be lost if such were the case. They are supposed to le so beautifully moulded trom bow to stern that no change from one to the other 1s apparent, so impereeptible is the blending. But the mark for cleaw flat still survives; move To mark the change. of hevels from the forward and after bodies, than any- thing else, or the Tien number line length. fo middle 31x ,thus x – of the 3B, r| length. Somarls as that is the middle of the see- water- The greatest beam , the ae, = water line *|| i 2 widest part of the yacht on deck, should be on seelion seven. From this point bend | batten To a illustrate the shape yow purpose for the side line, ending ferward at the end of the stem and aft at the half width of the transom, which is usually about half as wide as the boat \s amid ships. DESIGNING – 12. When the sheer and side line are drawn satis taclorily To your eye transfer the width and height of section number seven to the space you have ruled off for the body plan on the right of the sheer plan i Draw all the bow sections on the right: hand side of the center line and all the stern on the left. As number seven section, it corresponds }o the is the largest dead flat of 2 a ship. This is the first section in the affer =a /| body. Mark a spot where its width and height ae tere 1) a cari ee Delween these two points you are to yacht as near as possible To what you think is right for her ‘mid shia seélion, fRemembering always that a square, flat bottom gives stability and renga = a circular shape has little or none. That the more surface there is exposed the more surface Ee. the boat will have. The guesten of mid ship sections call for a knowledge of the stability of boats which is in itself a subject to & treated at as well be explained Jength,- and might when it first came up, as later, Nove i sealie section seven to the center line in the meet: Then transfer the clepth of keel on sketeh the shape of the . now, = 4 f pilh_ co of My” ; re ee Jaly-1890 The Beth The Pup – 1894 a Nov-1359 ES: ae DESIGNING— 13, We uill beqin with the ascow model wide and shallow, such as the modern small vacers now have. “This qives the qveatest amount of stability. because as when any weighT is . moved off to one side —— the shape of the boat is such that if quickl increases iPs bulk, away out near the edge to sustain that en he Whereas a circular wa — shaped section ina ‘ boat gives no such increase The Cartoon~ 1899. in the shape of the weight, but is me” ie the same shape, no matter how far she is her hilges to heeled over Small up clamps racin: boats, where against the She will the weight the wind, often help holo ap crew’s have a roll over until she off the edqe. weight 1s sufficient te saucer. shaped hold her section, and sliff up te the time when the deck edge begins To go under, they then are. the most dangerous. It you try to luge them , the stern, the end which has t% mov e by the action of the rudare very fast and der, in trying To turn only cals deeper unde r waler and a capsize is sure To result- unless you can relieve the pres sure and let her come up near. enough above the To a level water Qnother way keel is to to bring the deck edge put your uj and run off before the wind. This tends is turn the stern helm up and out of the water , but in doing sapeyes the craff. you try if while ih 30 adds tb the pressure on the sails and sometimes It is all right to wear off before the wind , provided the boat still has full headway on her and is not half stopped by her decks dragging under. ; The safest way , when knocked down so the deck. goes under, is to let the jib- sheets fly and So veliee » the bow and let her come into the wind, without cutting her side under by the. action of the rudder. het DESIGNING- 14. There is so little buoyancy in the lee side of such a model p inlo sink dleethem. theyto suslain up on edge fa that as soon as they getis enoug h boat the water before there But up To the time when they with the enormous sails they can juot keep their lee deek clear they are, ave able to earryand the small amount of boat there is le¢t To draq inthe water,most of ce being. lifted out when she heels, about the gastest kind of boats af oat. With the wind abeam or on the quarlec these long, shallow scows and are sailing on one long edge only have the minimum tesislance, In omeooth water and hard able te carry the maximum amount of sail. winds they are at their best, but in qeing to windward requive the Tenderest kind of nursing. There 1s so itle weight and s0 much big wile- like frame for the wind fo geta hold on that there 10 little or no momentum to them to carry them from vea [6 sea. This 1s ademon- strated by lupging dead inks the wind: your will find they donT earry, or fore reach as it is called, their own length. An ex pert at sailing these boals can,however, by the most cave ful to kind of steering and sail trimming get great speed out of them. windward, but if is acrobatic work for the erew. Tn the old sandbagqgers the trew with sand-lbogs; now they trim the weight, and a man with 250 lbs. worth his weight in gold. These ecows are built now on all the inland the healthiest kind of as sea-boats for salt ave wetler. had te trim her seows with human avowda pois 18 by the hundveds lakes and furnish recveation – but waler use there . | | ) | DESIGNING – 15. Next comes the high-sided scow, a step in the line of improvement from the skimmer we have Juol discussed. – water boat: More of a rough In smooth lake sailing itis naturally the lightest boat that will win, but when the > waves loeqin to form the boat that has more freehoard EE SSawill keep the weight of water off her deck and relain A Se Sher buoyancy longer than the one that euts under to : lee ward. =— In light winds the high-sidec seow had more weight To carry and more wind resislanee on the hull, and is not as fast, but now she has the ketter of if: and if properly designed will have as much buoyancy in her side, due to the lengthening, as the overhangs come inlo the water and the high freeboard, as she had in her boffom when upright. Duch boats as these sail faster, however, if a reduction is made in their sail When they begin to roll the weather side hah up m the air they will go better To windward if sail is reduced, and they are not al- lowed to heel over so far. Out with a free wind running they will earry all the sail the law allows, and This glat section fer center board a craft. Ballast does not hart a wonder ful power To carry sail, started that earries them the seas mm great them, either, but gives them and a momentum when bounding through But do not eon- too much; spread if | flat hoat. treated will have —— Old time ship- boals makes the gastesh kind of style. eentrate the ballast out in a Having boats we that will J more Too. of almost plat now lool =e into those what is called deadrise”’ builders used To qive ae all their ships a ¢erlain amount of V-shape to The bottom. Some gave the bottom an angle of. say, 3 degrees; some 5degrees, all according to their own personal experience in having built some ship that had a certain angle. Ty she was the most successful ship, in all probabilities the angle of dead-rise she had. would be found in nearly all that builders future boas. 21 DESIGNING — 16. Tn yachts where every man has a right . to dlesiqn as he ehooses,and carga carry 4 ing does not limit him, many a fanny shape has been produced by the men who knew just enough about designing To know nothing. lly about In center-board boats the angle of dead rise 19 usuaflu sh with puls the lee rail equal to that angle of heel, that djust e the water. In keel boats the dea rise is so variable ,and so littl of any one angle is To be found throughout their length, that if consi deralion. is not worth feet | ie – et [w weal ee \ sou many people make the mistake of nded To putting a keel ona boat never inte carey one. They seem to think any thing is a \t keel boat if you only bolt a keel on But this is no more true than you ean make a chicken out of a dog by stieking feathers on le a chicken but his actions will him. Youmay make him resemb so with boats. he decidedly dog~likes just types; one The center board and keel boats are two distbyinct Ws depth with r obtains 18 stability by if width, the othe a lead pendalum on it. keel, the slab deadwood keel There ave three kinds of keel boats. Thelartrueand best all around . and the fin-keel. The first [> the most popu The second is a cheap method of imitating a keel boat, but qaves a boat so True keel Slab Keel Fin Keel much surface that the skin resistance is a qreat the fin-keel is the perfect boat, cletriment to their speed. Theoretically leas t resistance; but pew desiqnass combining the greatest stability with the are right, they develap qrea. _ can turn out one that is perfeel- When they Larchm ont 30%, the 21° speed~as, for example, the Herre sho ff design a, fore runner of ‘them all. and El Chico and Dilemmthe of The secret of the desiqn lies in the faet that the shape they heel their hulls should be an elongated ellipse; 90 that when Popes DESIGNING ~ 17: over they do so evenly, and do not depress the bow and raise the stern, for that causes the cigar of lead on the fin to be drawn obliguely through the water mstead of in a true fore-and-aft line, as if should. CG common emor in designing a fin keel is in trying to add 1 the otability of the hull by making the hull flat This is like Taking Two different doctor’s medicines at the same time with the argument that if one ¢an eure you in Two weeks ,two ean do sain one. The result js usually 4 failure, just as the fin-lkeel boat that Tries 13 get olability from two conflicting sources. the hull should be round and full- sided, wilh freeboard enough To float the hull: when heeled af about 30 degrees , oo the deck edge does nof erowd under water The slab keel boat has this disadvantage; the fin ,being of wooden eonstruction , is many Times more cumbersome than the metal fin; this in itself destroys much of the good qualifies of the lead on its lower edge. It is always trying te float To the Surface sath ass es what you dont want it fo da Gna i 1’s 80 it takes much more power to push if bulky through the waler. Structuvally the alalb keel is a weaker construction shaped true keel. slal is than the 5- of course, of keels where the Weare >peaking, guile deep,as if would lee if the lead was as low as on the true keel ov fin keel boat The old type of V-shaped cutters ave now almost a thing of the past, for whieh we, in America, may he thank ful: Such: boats may be useful enough in British waters, where the sea gets up short and steep and yachls havele stay out and Take weather that Tayes large ships. The deep submerged body makes a sleady eraft in troubled walers,but it takes tons of ballast To make them stand up, without which they would Flop over on their side. Gnd as to speed, they are compared wilh modern hoals tremely slow. 2S. ey- DESIGNING — 13. You ‘ean iby now, probably decide the shape you want your mid ship section to be. The shape of this section gives you one spot to quide you in drawing the water line. – the width at section seven. With this width shape for your you in drawing all transferred To the half- breadth plan waler-line. Then you will have three spots To quide the other sections. water-line spots and the keel sketch in a You have the sheer spots, the spots. You will save lots of time and trouble now by skelehing in lightly the purposed shapes of sedllions, number three and nine, one and eleven, ond fwe, Then draw a diagonal line through the sections ao shown in opposite okei@h. When oketching these shapeo if ma help yow fo bear in mind the idea that the builder does just what yow are now doing. He euls out or moulds you have now sketched in temporary tem porary shapes ,as they are called, just as oeelions in pencil. 1p their shape suits his eye , if his judgment. can find no unfavorable ariti¢ism he proceeds to see if they are “fair, s0 that when he goes To bend This way the planking around it will touch fair on all the ynoulds. ia what you must now do,and the of doing if ts to bend the builder bends aq boatten around quickest and most accurale the sections his ribhands. just as , —~ Moulds and ribbands in place. A batten bent to draw adiagonal. DESIGNING – 19, On the plans these batlens are called diagonals, veCause they ran in a diagonal line across lines already drawn. The advantages of this ave that they the square eross the sections at nearly right angles,instead of a very aeule angle, as the water lines and buttock Jmes do on some of the seclions where the exaeT point Diagonals. of intersection is hard any wheres from A‘Tfo B, as “ To determine, and may vary shown (n oliagram. see The quickest way of taking off the measurements ote of Paper so one edge \s along the is diagonal to to lay a be fatred and mark where each seclion crosses if also where the eente line crosses. Transfer these measurements fo their corresponding seélions in the lower halt of the half- breadth pan, Keeping the center line marked X onthe center line in the hale-breadth plan. spots through This will give you a series of which a batlen should bend faic, Touching each point, To find where these diagonals end, measure the heigh from the base line up fo where the diagonal crosses the eenler line – in the ection tothe sheer plan to plan and trans fer this see how and afton the stern such a tay height forward on the stem height will cross the out- j line of the hull in the sheer plan. These distances forwared of section one and aft of eleven when trans- | fered to the half -preadth diagonals. loealé the endings of the If the batlen does not bend ina tue fair curve if shows that (f the frames were put up that way the planking would not toueh all the frames and shims* would have to be put in, whieh is an undesirable practice. But to you it shows that your Judg ment in skefeh ing in the approx imale secfions was at tault So change the seclions that are unfair at the di agonal as the batten shows if curves to make the Don’t fovee the katlen info unfaw line go through the spots, but alter the opals. RS. – 20 DESIGNING On the other hand, clo nit make the common error most amateurs fall info of allowing the batten to decide the design for you: The batten naturally will bend 20 as to make every line tend fo a spindle shape in water-lines, buttocks and dia onals, Fixa shapef your ideal looat sn your imagination and draw it loy the use of battens, but dont allow the batten to alter your ideal. ® attens tapered from one end, from the middle foward each end, and of parallel shape throughout, will come in useful in various places To draw the required shape. For instance, if is ditfieult to make a parallel shaped batten bend in any thing else but an are ofa circle while a batten tapered je one end produces the parabolic curve and one tapered each Bay from the middle produces an ellretieal segment. When the sections that the diagonal ee Are Rrabolic show are unfair have been altered tg agree with the diagonal , you Elliptical have another part of the ylan Vest we faired up. By the use of intermediate diagonals all the sections can he made absolutely fair Then to make the plan complele , although they are of secondary importance, as fairing up lines, draw in all the buttock and water lines. 16 draw a line To represent Before you finish the keel you will have the half widtns on the bottom of if. This calls for practical experience and a knowledge of construction. [fF she is a keel Jnoat, see that there 19 area enough in the keel to give you the required weight of lead or iron. ip @ center-board boat, see that there is width enough for the alot: When you first draw the keel carry the vides down To a square To fair up by and then round the edges off To edge to make it easier cuit Your oun ideas i afferwarols. lt the lead keel be a short loulb shape, draw enough intermediate seétions to accurately show ils – shape In drawing a plan always bear in mind that the yee 2 whole purpese of the ° oe 1 design Is tobe a elear quide for some one else , it may be built from. to reproduce full 513%50 Rb. { M Mh ee be Be Hy m = Plan of Lead Keel. Tor oy DESIGNING- ZI. Give enough lines so the boat builder can see how you produced. The straight line indicating the rudoler post , for instance, carry your eurves {Pf upto some main |ine, suchas the water line and down to the base line, giving – the measurements to these spols from somé seclion. Ip any curves are swept with a compass que measurements, indieating the pomt Twas swept from. Remember, the plan is something To he made use of, and not an ink dyawing To hang on the wall in a Ss frame. The transom is one of the most olf~ To draw. ficult parts of a design. Te show its true shape requires ¢on- hereto i! siderable projection, Morethan even the average boat builder is capable of: It 1s easy enough to draw the shape of the mould just forward of the transom, but the transom boeing cut under ona loevel and having a curved face, as most of them clo,make if very diffieult “To project a curved +tace transom, draw in louttoeck lines about every six inches apart, from section eleven aft you alread y have them drawn every twelve inches apart, Then decide on how much crown or arch yow want your deel te have , a halg’inch to every foot of beam is usual in small yachh, and draw this curve the half- lbreadth plan or’keam mould” as beat builders eall it, across rom side To side, 3 Panning the fall width of the boat at each section – this will give you the amount of arch or crown the deck will have at each section. Measure these distances above your sheer line and draw a line that will indicate the middle height of the deck, as at N | | | Taco Le A,B,¢ and D. Then decide how mueh ofa hend you want the face of the Transom to have, A remembering that if the transom is to be built up, as it will be if it has much of depth, and not carved out solid wood, That the boat- builder has to steam and bend thewood to give if the curve you-want. R71. DESIGNING — 22, If you want three, four or six inches of curve, meas ure that distance up square from the face of the transom to where le crosses the side side line line; that will qve yow the ending of the hoat- Middle of Deck Side of Deck of the To find the spols To draw the vest stern ae you muat earry the buttock lines up on the Transom and along the deck. So mark out a ‘ Side of Deck aa for the curve similar fe the face of the transomy if you decide on four inches, draw an are of a eirele thar aurves up fourinches in the Full width the deck at the Transom- across Middle bine 6G” Bullock (2″(Beilfock Each side of the middle Ine on this are measuve off the dislance <—— Ful{ width of HeTeck across Transom———> \ the huttock lines are away from the middle, and these distances, Ate Band ,Atee, will qve you the Aislance the transom has curved up rom the middle line on those buttock the deck eurve and find out out ,12 inches out, efe. of the Transom and face Do the same with lines. how much the deck drops 6 inches By measuring these distances up from the down from the middle of the deek you can draw paralle| lines, those distances away, and where the deck and transom lines meet you have spots To show yow how To draw the curve indiealing the deek edge ,and where the transom and buttock lines cross you have spots for the knuekle line. ae iS Middle Line a ots When the yachts lines are all drawn, rule offa sheet of paper en which you can mark all ihe measurements necessary for the builder To have to plans floor. on his mould loft This he must do before he ean to full Proceed to _ Middle Line reproduce those size build the boat Such a sheet is called the” Table of Offsets? Projection of Transom. 28. ABLE OF @FFSETS “ FOR. 32-root water tine stoop MON SOON’ Designed gor MrFE D.M.Strachan | Ququst – 1599. – Heights Stem| | to.- Brunswick, Gia Under side plankahr| 8-64 Under ste decks| 5-67| Under side wood keel Rabbet |_Botlim af iron keel Builloek * 1 2 3 x 7:72| 7-3° 14-117] 7-27| 2-72 |7-48| 4-0 |3-14|2-3″| of-07|3-1%| 2-37| 2-10″| 1-9%| $-85|of-3?| 3-Y?| 2-6] ¥-0%| 17 alls 5-08) : “if : pana a 5 6 2 be Hi 6-5″ | 6-6°| 6-41 6-3°| 6-2?|6-27| 6-4″| 6-7″| 6-7°| 7.07 7-0 7-25 | 7-07 |6-107}6-9-16-5 | 6-5’| 6-8″ | 6-10″ -8?| 1-34] 1-1 10°] 1-0 | 1-0 1-87) 1-4? | 1-38| 1-89| 2-81 4-0 | 4-10 | 7” /-0′ | 0-6″ |0-2?| 0-17|0-2’| 0-5? 1-11? | 1-6″ |1-67 | 2-0″| 9-07 |y4-2°| F-0 | 5-9″ LY 4-1 3-4 | 2-9| 2-15 | 1-94 | 1-10″| 2-4 3-8! | 4-3’| 5-1? |$10″ F238″ | 3-104 3-0’| 2-4″ 2-1’| 2-14| 2-7″ | oF | 4-4 $2″ |E-M4 2-5?) 4-77| $-67| 6-84) 6-7? [6-97 | 6-8| 6-27|F3″|/-0 1:77 | 4-0? | §:05| 6-3″| 6-8 | 6-8″ | 6-b°|570″| 37° BY| 2) 6-0 16-5″) 6-F’| 6-14 yi” 1-86 | 2-19°| 5-3°| F-11| 6-0 |F-Y7|3-0 0-85| 4-7! |F-3* | 5-6″ | 4-1″ | 0-10″ 3237 | 4-3″ | 4-0°| 2-5~ 13° | 2-7″ | 2-54 0-9 2-12| a5| -5| b-Y7| b-U5| 7-35| 7-34 |7-2TM| 6-10″| b-25| FY! 4-3? iagonal N2 | 1-10| 3-9°\ 6-04 b-07| 6-84 | 7-0°|7-05 6-9 5-0 4-1| IF* | 2-7″ :5 2 : 3 G5 |3-0% | f-27|F0’| FF? |6-0% |FM| F54| 4-6″|3-6″ |2-6° . 4A 09>| 1-08| 24-7 4-0 | 4822? |Y! 524 | 2-7″ | 7-2? Mould Stations Water Lines are are Buttock Lines are _———— Knuckle! Tip- 0-5| 3-3? | 1? FUY| 6-7? | 6-107 |b-10″| 6-97 |6-S| FF? | HS WZ 3 = |7 | & | F | 10 | I {12 1-37 | 38-7″ |F-17| 6-08| 6-7″| 6-107| 6-16-94] 6-6 |FU E-0? |3-2 WL oF @ % 5 | 6 New Rochelle, N.Y. 2-13 | 3-104 F-27| 6-0°| 6-7? | 6-107| 6-11°| 6-95| 6-6″ | 6-0 |F-3′ |g -y?| 3-1/4 0-2%|0-2°|0-3¢| 0-4’ |0-5*|9-6° |0-5!|0-4|0-3’|0.2″| 0-2″ |o2* Planksheee Siding of weed Lee . le NA. HAG 2-81 | 22S” |213-9 |G |FY|b-3? IHalt Breadths at : Noe 4 . By Mr Charles G. Davis, 4-0″ apart: Diagonal * | cats center Ime 7-9° above; W-L4G—- 6-2 out, 26 Disjenale 6″ apart Diagonal 3 part 12° apart Diagonal 4 ~ SS aq. |/-6° as eaeDave HO eet» 6es:pes FW: , eo 6-0° yw. pees5 THE CALCULATIONS. The necessary calculalions to be made to determine the eeriters of a boat from the plans are in themselves guile simple. But the judgment necessary To decide the relative posilions of these centers 50.as fo give the best results for the. work the vessel is intended To do, can only be learned hy experience the same A few general vules may be cited; butjas you will later observe, results ean sometimes be obtained by two extremely opposite types. The center of . buoyancy and displacement ave fiqured from the same set of measurements. The center of lateral resistance from another, the center of effort from another, and soon. These names | know sound like so much Greek to those who need help at this slaqe of the game, and so [ will explain them a lille more explicit! x Take first the calculation for displacement. This merely means how much space does the boat, from the waler line down occupy. When lowered into the water it pushes aside or displaces (which explains the term ) a certain amount of water and calealaling dis placement means To fiqure how many square feet of water is pushed aside by the baat. H would be just the same were if @ square box we were considering, and it may be easier for some people to comprehend when referring fo a box; some get the idea into their head that beeause a is some hidden 30 many curved surfaces that there with wt the water but there is not. boat is shaped inlo science connected The same princi ples that apply To a box on apply To the boat. The only difference is you can not figure out the number of square feet in the boat so easily as you ean the hox A box 2 feet square if sunk a foot deep, would displace We sue @ 82% )= 4 94. fl of water But a boat 20 feet long on the water-lne & ff wide and 2 fl. deep would not displace what the product (2Ox%x2%~- 320 4. ft of waler) which those figures give, because the boat is 30 shaped that more than half the bulk is cut away. By actual figures. comparing. two extreme types, we have Aleatorda– e-b- yaw|—- » 35 wl % wl x Virginia: -keel- sehooner~ 46* DiO< ee beam x 3 draught = 1533 sq. ft 15 beam x 7* draught= 5197 99 Ft THE CALCULATIONS. - 2. Alecatorda’s actual displacement was only cubic fest contained full- hodied in a block 435 39. ft, or ay of 1533, the of her ‘dimensions. She was an boal Virginia was much deeper. Her length x 2q-ft, but she only of ner deep keel. occupied breadth extremely x depth qave 5/97 124% of this, or G46 sq ft, on account ee Ce ga ae Alcatorda Virginia Ships have a block coefficient , as this per centage is ealled , as high as 55 to 65%, but that is because their mid ship shape is almost a square Yachts box in shape and they having sharper ends To calculate how mueh when floating aT any Jo explain To you. will float the necessary and deeper kkels bulk desired ‘It is are so very bluff: ended. have or displacement important weights at her 1 know purposed bulk. aq boat will have depth on the model very lees is what | am about this, to be sure she water: line. On ‘the plan clivide the waterline length into ten equal parts, this counting the ends .qives you eleven lines or sections and Ten spaces. Number the first line one, and 60 on to eleven, One being the forward end of the water-lne and eleven aft. Saetion number six is the midship seclion. le you know how to use a planimefer, and have one availabl , run e it over the plan feet: and compute the avea of each half seclion as drawn in I not, dvaw enough small angles to enable you 16 fiqure the area Triangulation, This is done as follows ;- multiply the distance Fia- 1 on line “a,” Fig >|, by the combined lengths of lines this produet “b’and”e”; will be twice the area of the hale section, Si. G planimeler. square by THE CALCULATIONS. – 2, So divide by 2, or leave it, as you would only have to multiply by 2 later iawn he woulou you ean equalire the ‘wine. glass sections of keel boals into a triangle, Another way, Fig 3, is to rule the seclion off info small squares and ada them uP; piecing the cut squares together to make up whole ones. Senne ee “s Eis 2: “] NESSES a ea nea iL ol When you have figured the area of each half sec~ tion write them in tabulated form as shown, The whole secret of Ley figuring displacement 1s contained in a rule,called Simpsons (Rule, which reads as follows: Gmended so as to simpli¢y it) Malti ply the first area by 1, the second by 4, the third by 2; then alternatel by H,2.4,.2, ele, upto secfion 10% then section II,the last section multiply by | again. Multiply the sum of these products by 2 to give you both sides of the the seclions, and ment in divide cuble feet ly Sedtio [RPE] Products / 2 o S| | eel A | 16.7] Sr | ! 4 yee 6 23.7 4. ii Wes ise Ie: 7. he 144? | 2 6. 4 2 Le 8. 6% tor fresh fe) be the by displace – 64 for salt In the following table theareas 24 Produets 5 ee 4 3 65“ 66% | 2 (35% / he (o} 4o? | Zee Ne pose ie 3 4 Q a er ee * | seefion in sq.ft. as figured by Zafiees 4267 multiply the spacing between water. 202 Hane by The quotient will To get it in pounds water and Area by boat,and also §2* | planimeter, or by either of the 43° | other methods The sum I have explained. of the products 426-7 js now multiplied by 3207 the apacing between the Ho” | sections and divided by 3; EEN ie get -the cubic feet in boat 55 LOE” i ie below the water-line. kt the spacing were 3° fh multiply A26’* by 3° and the produet 149/.7 divided by 3 gives a quohient of 497.6 cubic feet displacement. As the areas qiwven represent both sides if is not neeessary To double them. 32. ~ THE CALCULATIONS. — 4. To veduce this to tons divide by 35, as there are 35 eubie feet of salt water to a Ton. To get if in pounds multiply by 64 for salt waler and 62 fer resh. . AG 25T + 35= [41% Tors. 497: 2% bik= 3/52 (os. displacement: lf you Me a pan full to the brim with model yaehT inlo catch what waler if some of that waler runs out and water and then has to place a over flow. put it in one side of a Ip you pair o seales and the. model in the other side one will exactly balane. the other, proving to those unfamiliar with such subjects thata boat has To displace or push aside her own weight in wafer. Or If you had a Ary dock full of waler and should measure you the launch a height the walter rises can easil pane ship into itand her weight hy multiplying the length by the breadth of the dock and the product hy the height the water rose, and this by 64 or 62, aeeording to whether iT was salt or fresh water. Supposing the ship didAt have her machinery in. you would fina that as all this was put in place – boilers, engines, piping,ele., everything in fact that was put aboard of her would sink her deeper into the waler and eause the water in the dock To rise correspondingly higher- By measuring the water you could tell the weights of every thing going info the ship. If you walk from one end of a boat to the other you cause one end to go down and the other to rise; this shows that there is some one point where the boat acts as on a pwot. This point js called her center of buoy ancy or cenler of displacement. You can find if b moving a heayy weight forward and aft along a boats deck until both ends are depressed exaetly the same, But in designing you must he able to ealculate this center long before, the yaeht is built, and be so sure of it that you ean bolt on a heavy keel and have it sink her just right THE CALCULATIONS.— 5- To calculate the posilion of the center of buoyancy , go back to the table on page 3. As sxeclion number six is the middle of the waler line, start ¢rom there and multiply the products already obtained Then add up all 7% 11 the second in the after seclions. products from by 1,2,3,4 and Gas shown. 1 te 5 in the bow sections The sum of the after sediions is usually and the lavger. Subtract the smaller from the lamer and divide the remamder by the swm of the first products. center of The result multiplied by the opacing shows how far the buoyancy is ford ov aft S71]= BIO = | 77 aft of section secon 31x. TJs 426″ * 181 *& 3 spacing of sections = is of number ./5/ .633 ft the distance the cenler of luoyancy six. To determine the vertical position of the center of buoyaney iF is necessary to figure the area of each water line separately, and then draw a curve through a Series of spots on the various water lines I the area of the load water line measures from the center line on a seale of that represent the various areas. 40 sy ft-mark a spot % inches out “a inch to the foot. This means every ‘/rinch repre – sents 10 sq ft There. may be only three, four or fe water lines below the load waler line, but that will be enough to que you spots te draw the curve through. EWb 2 50. Then treat this curve as a new bw area, Divide it info Ten equal parts from the keel to the LW.L. and measure the lengths of the ordinales of each spot 30 found on the fe inch seale, he Ay scale aS of to sft te the {ninch. Keel By Dimp sons Rale you qet the same aney number of cubie inslead -of the keel feet oeing and ques displacement as Fiqueed you ae in you had be fove » but the center a foreand – aff direction is now fiqured 4p from fs distance below the water line. 2.8 Tw. Cueva of] section areas EAL a ena Ne of buoy- | See