Page 293 - Practical Ship Design

Design qf Lines 25 1

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Stern as Built With Transom Wedge

Fig. 8.14. Ro-Ro ferry stern plans. Transom wedge added to increase KM (by more than 1.7 m).

described in $8.3, giving the propeller a semi-tunnel position. Whether this
arrangement would increase or reduce the power required is not known, but the
latter seems equally likely. The gain in KM (from the basis) resulting from this
change increases to 12%.

8.6.4 V sections and high rise offloor

For various reasons, neither of these modifications were applicable to the ships
which were used as the basis of the study. V sections undoubtedly improve stability.
If fitted forward they tend to increase the power required; fitted aft they can be
good from a powering point of view particularly if associated with “straight”
buttocks. They do not always suit the internal arrangement of the ship too well
particularly if carried to an extreme.
The use of high rise of floor can improve the stability but almost certainly means
increasing the depth and draft of the ship if the displacement and internal volume
are not to suffer.