of half model was in use in England and in tlie colonies 

 at least as early as 1715. The lines \vere taken off in 

 various ways; the most usual was to trace tlie profile 

 on a board and then to draw perix-ndiculars to the 

 keel to represent frames. Next the model was fas- 

 tened to this board so that its profile coincided with 

 that on the backboard and saw cuts were made at 

 each frame line in the model, care being taken that the 

 saw cuts were \-ertical to the backlioard and coincided 

 exactly with the frame lines at the top and Iwttom of 

 the model. By in.serting note paper or cardboard in 

 each .saw cut the frame shape could be traced and. 

 with suitable ordinates drawn, could be measured and 

 transferred to the mould loft. .Some builders took 

 off the frame shapes with soft lead bars about ^(e inch 

 square, but this required much |)ractice to oljtain 

 rcasonal)lc accuracy. Others used a laborious tem- 

 plate-cutting operation or had a form of pantograph 

 that allowed a pencil point on a drawing board to 

 move exactly parallel to the surface of the model at 

 each station. The solid block model remained in u.se 

 until the end of the I'Hh century on some sections of 

 the .\merican coast. 



HAWK'S NEST MODELS 



The third type of half-model was called the "hawk's 

 nest,"' or "crow's nest," model and was particularly 

 popular from 1780 to 1820 on the Atlantic seaboard. 

 This model was made up of a plank backljonrd. or 

 sawn-out profile of the hull, with plank sections 

 mounted on it to represent mould frames. These 

 were usually fastened to the profile, or backboard, by 

 nailing from the back of the latter and were held 

 rigid and vertical to the backboard by battens bent 

 around the plank sections or by a deck or sheer piece. 

 Lines were taken off by removing any battens that 

 would interfere and then tracing the outline of each 

 frame section on cardboard or paper. The earliest 

 use of the hawk's nest model yet established is 1752, 

 in England, but the model type was probably used in 

 the late 17th century, along with the solid block model. 

 This style of model was used in some isolated American 

 areas as late as 1880 but, being quite difficult to shape, 

 it was never as widely used as the block and lift 

 models. 



Using the Models 



A vessel or boat may l)e as well shaped, or designed, 

 by use of the half-model as by use of lines drawings, 

 so far as form of hull is concerned. Methods were 



developed in the early 19th century by which the 

 necessary basic calculations of naval architecture 

 could be made from half-models.' Undoubtedly the 

 half-model gives a more complete and precise impres- 

 sion of the hull form than does a lines drawing. The 

 half model produces the same 3-dimensional effect as 

 the finished vessel, something a lines drawing will 

 not do. Hence a lines drawing may produce in the 

 finished hull form an undesiraiile feature that would 

 be discovered at once in a half-model. In general, 

 the ability to design fcd judge hull form is more 

 readily acquired by use of the half-model than by use 

 of lines plans and other drawings. Many boatbuilders, 

 ship carpenters, and even fishermen can quickly 

 develop a good judgment of hull form through use 

 of the half-model, whereas some well educated naval 

 architects, using only drawings, never acquire sound 

 judgment of form. 



The accuracy witii which a designer may convey 

 his ideas to the loft and to the builder is as about as 

 great with the half-model as with plans, if both are 

 equally well made, and, of course, where builders 

 are poorly trained, the half-model conveys more 

 than do plans. The efficiency of the half-model in 

 hull design is the reason why it still sur\ives, in spite 

 cf the increased use of plans. 



There were many other variations in model con- 

 struction: one form combining horizontal with vertical 

 lifts; the latter glued; to make what some call the 

 "checkerboard" model, for the lifts were of various 

 natural wood colors. This was a decorati\e model 

 having no particular practical value, except to show 

 the skill of its maker. In a more common form, the 

 block with every frame, square, and cant was care- 

 fully cut, the whole mounted was on a backboard 

 and fitted with planked wales and topsides after the 

 lines had been taken off. This, too, was highly 

 decorative, but it had practical advantages. Hawk's 

 nest models completely planked after the lines were 

 taken off are also sometimes found; these were very 

 popular in England in the last half of the 19th cen- 

 tury. 



Historical note 



The introductions that precede each section of 

 this work cover much ground not illustrated by the 

 models, but which should be known in order to 

 appreciate the value of the collection, as well as 

 its shortcomings. By treating as units in these 

 introductions the important vessel types, a more 

 detailed account of their development is possible. 



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