[PCW] Drive options for displacement powercats

[gill.tt at comcast.net]

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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