Page 268 - Nicolaes Witsen & Shipbuilding in the Dutch Golden Age

Table 1. Comparison of Witsen’s and Van Yk’s shipbuilding formulas.
Tables
A key dimension in Witsen’s formulas is the width (thickness) of the inboard face of the stem, whic h was calculated as one inch for ever y ten feet of the ship’s total length. Almost half of Witsen’s formulas (about 46 percent) are based on the width of the inside stem. Van Yk’s formulas also use this reference point but to a much lesser degree (about 10 percent). Compared with Witsen, Van Yk uses a wider range of criteria to obtain the dimensions of components, with reference points like the keel, wing transom, and the main dimensions of the ship. While many of the formulas in both Witsen’s and Van Yk’s treatises remained constant throughout the seventeenth c entury, some changed in response to the f ashion of the day. With this second group of formulas (indicated with italics in the table below), we should therefore pay considerable attention to the period in whic h they were applied.
Key
L = Length of ship between outsides of stem and stern
W = Width (beam) of ship, measured over frames (without planking)
D = Depth in hold, me asured between top of keel and top of lower deck beams without camber
i.s.=widthofinsidestem=1⁄10 inchper1footL(or1cmper112cmL)
Witsen’s Formulas
Ship’s dimensions: L : W : D = 20 : 5 : 2
Keel:
Width = 11⁄2 i.s. Height = 11⁄4 i.s.
Stem:
Width outside = 3⁄5 to 3⁄4 i.s. Breadth = in the middle, 3 × i.s. Height = D + deck rising + “ ’tween
decks” + forecastle deck Or: 2⁄11 L
Or: 11⁄60 L
Rake = 28⁄29 height of stem
Van Yk’s Formulas
Main dimensions of ships:
W = 1⁄4 L
D = 3⁄4 W − (height of bulwark + height
“ ’tween decks”)
Or: D = 40%–50% W
Keel:
Length = 9⁄10 L Width=1inchper7feetW
Height = a little bit less than its width Length of joints = 5 inches per 1 inch
width of keel (two bolts per 2 feet
length of joint) Stem:
Height = D + deck rising (1 inch per 10 feet) + height “ ’tween decks” + anything above that
Width = 1⁄10 inch per 1 foot L
Width outside stem = width i.s. − 1 or
2 inches
Breadth = in the middle, 2 × w idth;
above and below, a bit more Rake = not specified
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