Hi Andrew,
I don't think that Sean was looking for 18kts. I don't know of any big sailing catamarans that can exceed 12kts under power, even with twin 150+hp diesels. I doubt that his proposed twin Yanmar 30s would hit 10kts with that much windage.
I don't think that Sean has stated a specific target speed, but I would think that 8kts could be sufficient.
His stated displacement is 11,000 lbs empty, with a max loaded displacement of 18k lbs (maybe that's where you got the 18kts). I'll guess that his target weight will be around 15,000 lbs.
I do like the concept of the pods on legs, the tough part is engineering the hinge to take all of the thrust on a long lever arm like that. I would think about a trailing brace angled from the hull down to a point near the pod, it would be a little extra drag under power, but the brace would be entirely under tension (maybe it could be synthetic line, basically a backstay for the motor sprit) and would really help when the boat is motoring in rough seas.
It does bring us back to finding reliable pods in the 10kW+ range. Is anyone in this group actually running a larger pod like that? Is anyone in this group actually running a 3kW+ pod? (Torqeedo 4.0s don't count) Not one that you read about, one that you have actually used.
Fair winds,
Eric
Marina del Rey, CA
--- In electricboats@yahoogroups.com, Andrew Gilchrist <andrew@...> wrote:
>
> Thats a good get!
>
> that cat is lighter at 13-14000lbs than the DD of Sean'st
> the electric power ratio is 67% the petrol peak power 20 vs 29kw
> and the displacement is a simialr 72% of Seans cat
> and the setup is for wind+solar regen+25kw battery
> so it is a 6 knot setup
> Sean was after 18knot similar power to deisel and electric diesel.
>
> That setup is very very neat and practical
>
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