[PCW] Drive options for displacement powercats

[sealubber7 at aol.com]

Some years ago, some of the better RIB's (Otech Marine for example) were putting a diesel in the center console with a jack shaft to an out drive to provide much improved balance and weight distribution. Not likely an option in "cats" due to space utilizations, but in commercial applications maybe. Made all the difference in the world in rough weather, high performance use. A little more maintance for a jack shaft, but well worth it.


-----Original Message-----
From: gill.tt at comcast.net
To: power-catamaran at lists.samurai.com
Sent: Sun, 27 Apr 2008 11:36 am
Subject: [PCW] Drive options for displacement powercats



Bob, et. al.

Do the Volvo Penta IPS and Cummins Zeus drives fit within the same category as 
the outdrive, with respect to most of the advantages and disadvantages you 
discussed?  Yes, it is my understanding that they cannot be lifted out of the 
water while moored or docked, and the corrosion potentials may yet be unknown.  

Do they have trim capability?  Does one lose efficiencies if the drives are 
protected by a skeg in a fashion similar to standard inboard propulsion 
arrangements for trawlers?  Some tug bots have Z-drives; how are these drives 
protected from the occasional dead head or submerged shipping container?  

The fore-aft trim problem would seem to be better resolved with a Zeus type of 
arrangement, as there would seem to be greater design freedom for the naval 
architect with respect to engine placement.  

The photographs that I have reviewed also show a more spacious engine room with 
this design, due to a more compact propulsion unit.

Thoughts and comments greatly appreciated.

Gill

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