[PCW] CS hull form

[Malcolm Tennant]

John,

I agree that there is certainly a case to be made for wider bodied 
hulls in some situations. You are assuming that the use of the CS 
hull form automatically means a high L:B ratio. This is not true. You 
can use the CS hull with any fineness ratio although it does tend to 
be associated with L:B ratios of at least 10:1. However there is no 
reason why it cannot be used with L:B ratios of 8:1, or less if you 
wished. and in fact has.What is more important hydrodynamically, than 
the L:B ratio of the CS hull is the considerably decreased appendage 
drag and enhanced propeller protection that it affords. This 
appendage drag could be decreased even further by getting rid of the 
rudders and using the electronically controlled engine rpms to steer. 
Unfortunately this would probably preclude the use of one engine and 
the classicication societies are less than enthusiatic about the idea.

As well as those designers choosing not using the CS form are in fact 
a large number of designers who are using the CS hull form:- In the 
USA Manta is not alone; PDQs latest offering has this hull as does 
the new [and very impressive] Maine Cat. Photos of the Maine Cat show 
a hull that is a dead ringer for the hull of the Escape and that 
should be very efficient. I look forward to seeing some controlled 
fuel consumption and performance tests of this boat.

In Australia:- Chamberlin, Schionning, Lidgard,Grainger and Brady all 
use the CS hull form and I suspect there are a few others.

Aside from Derek Kelsal and myself, the CS form is used by Gavin 
Cooke and Richard Mcbride and Allan Walker are producing commercial 
designs in alloy with the CS hulls.

Horses for courses!

Regards,

Malcolm Tennant.


MALCOLM TENNANT MULTIHULL DESIGN LTD
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