From some modern texts on the design of wooden boats:

**Sailing Yacht Design**: by Douglas Philips-Bert:

*Weight Calculations. *

* These are not often made for small craft, except when built to rated classes or of an uncommon breed on which there is little data. With larger craft weight approximations are sometimes necessary, and particularly so when no inside ballast, except a little for trimming purposes, is to be used. Indeed, if weight calculations were not so time consuming, it is doubtful if the praises of inside ballast would ever be sung so cheerfully. With wood construction, however, weights are always approximate owing to the uncertain density of timber, which varies by 20 percent or more depending on green and seasoned states. Weight calculations are to a large extent common sense and dreary arithmetic, palliated by the intelligent use of approximations. *

* One of them is the cubic number. By its means the structural weight of yacht may be approximated from that of a similar yacht, of the same type of scantlings, but of any size. The cubic number may be accepted as:*

__( LOA x Max. beam x Depth of hull)__

* 100*

*the later quantity excluding the fin keel, and being measured to point of greatest body depth. The structural weights vary in different yachts in the same proportion as their cubic numbers. *

[Detailed calculations]

*Planking: Area multiplied by the thickness...*

*Frames and Timbers: The area of the frames will be a certain proportion of that of the planking, the proportion depending on the siding and spacing of the frames. ....*

*Keel, Stem, Sternpost and Deadwood: Approximations are best made when dealing with these members, since their irregular shapes make the calculations of volume difficult.*

*Stringers, Gunwales, Shelves and Clamps: The length of these may be measured from the drawings....*

*Deck: The area is most simply measured with a planimeter...*

*Deck Beams: The siding and spacing of the beams show what proportion they bear to the deck area....Allowances must be made for heavy beams [at masts or hatches], and for hanging and lodging knees.*

*Joiner Work and Furnishings: This may be worked out by proportions from similar craft. The only other method is to consider each item in turn.*

**Skeen's Elements of Yacht Design**: Rev. by Francis Kinney

*Comparative Weights*

* To make a rough estimate of the weight of a new boat based on the know weight of an old boat multiply the weight of the old boat by the length of the new boat divided by the length of the old boat. *

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If the ratios of draught/length and beam/length are similar for the old and new boat, then the two formulas give the same estimate.