Page 121 - Practical Ship Design

88 Chapter 4

Scrap percentage corrections:

Add 1% for passengers
Add 1 to 2% for light scantlings

Deduct 1.5 to 2% for L > 300 m
1 to 1.5% for 200 rn < L < 300 m

Add 0.5 to 1% for 60 m > L > 100 m
1 to 2% for 45 m > L > 60 m
3% for L < 45 m
Check also against similar ships

Block coefficient at 415 depth

Fig. 4.2. Scrap percentage versus block coefficient.

derived by regression analysis techniques and the indices allotted to the dimensions
of L, B, D and C, vary widely, and unfortunately in most cases the resultant figures
appear to have little physical significance.
The base numeral suggested in 54.2.1, although better than most others in
general use, lacks theoretical justification and it seems worth investigating whether a
better data base can be devised.
In trying to do this, naval architects have become divided between methods
based on volume and methods based on beam analogy. The truth appears to lie
somewhere between, with part of the weight being volume-dependent and part
modulus-dependent - a concept recognised by Eames and Drummond in their
1976 R.I.N.A. paper “Concept exploration” and by Sato in a 1967 S.N.A.M.E.
paper “Effect of principal dimensions on weight and cost”.