Seakeeptng Constderattons tn a Total Destgn Methodology 
Such an analysis does however require a quantification of per- 
formance parameters that are very difficult to quantify. The author 
has bravely stocked this problem but I wonder whether his assump- 
tions concerning the effects of overall size on hull efficiency elements 
are not oversimplified. Also for instance SHP,is not always equal to 
EHP/1, - a paradox that is discussed at length within the I. T. T.C. 
and elsewhere. 
The example given is particularly interesting, not only asa 
demonstration of the method, but also for the result obtained. In this 
case, the ship with twice the displacement is shown to be better able 
to maintain speed ina seaway. This result is not surprising. What is 
surprising however is that the difference appears to be so slight. 
Here is an example of two vessels, designed for the same 
speed but with one having twice the displacement, and hence twice the 
payload of the other. A comparative through costing of performance 
would therefore need to compare the profitability of one ship versus 
two and would involve an assessment of profound differences of de- 
ployment, availability, and manning, as well as first cost. 
I suggest that these outweigh the seakeeping speed and fuel 
effects to an extent that one can conclude that these may be ignored 
when determining the overall size of a large merchant ship design, 
even when large changes are possible. In other words, the first ite- 
ration is redundant in such a case and efforts should be concentrated 
on evolving detailed design improvements - incorporation of adequate 
freeboard, suitable bow sections to avoid slamming and so on. 
I am not however suggesting that a systems approach including 
seakeeping is always unnecessary. Such an approach is appropriate 
for smaller vessels and is indeed vitally necessary for the design of 
small warships, where other considerations of crew operation and 
weapon deployment become dominant, 
REPLY TO DISCUSSION 
Chryssostomos Chryssostomidis 
Massachusetts Instttute of Technology 
Cambridge, Massachusetts, U.S.A. 
Thank you Dr. Lover. I agree with all your conclusions. 
1627 
