Page 92 - Practical Ship Design

Chapter 3

= capacity depth in metres
= D + C, + S,
= depth moulded in metres
= mean camber in metres = 2/3C for parabolic camber
= mean sheer in metres = 1/6(Sf + Sa) for parabolic sheer
= block coefficient at the moulded depth
= total moulded volume of the ship below the upper deck and
between perpendiculars in cubic metres
= total cargo capacity required in cubic metres
= cargo capacity above the upper deck in cubic metres
= deduction for structure within the cargo space expressed as a
proportion of the moulded volume
= moulded volume equivalent to required cargo capacity below upper
deck = (V, - Vu)/( 1 - S)
= ratio of cargo capacity below the upper deck, to the total moulded
volume = (V, - vu)/vh
= other volume required for accommodation, stores, machinery,
tanks and other non-usable space within the volume vh in cubic
metres (non-usable space depends on the type of cargo carried
and corresponding type of capacity measurement).
It is interesting to note that the draft T does not appear in these equations,
although it is implicit as a second-order term in the difference between the value of
C,, and that of C, at draft T which is established by the form required to suit the
Froude number of the ship.
In a way analogous to that given for the weight equation, the volume equation
(3.6) can be converted to:

(3.9)

A relationship between C,, at the moulded draft and Chf at a depth D is given by
eq. (3.10).

(3.10)

There is some ambiguity in this book in the treatment of block coefficient at
other than the load draft. In some chapters C,’ has been taken at the moulded depth
D, and it would have been better if it had been possible to stick to this throughout
the book both for the sake of uniformity and because it has a better theoretical