[MHml] engine power

[David Farmer]

Bill,
  Don't know if this is of any value to you but, I spent a week aboard Dave 
Crowe's 70' Morelli designed crusing cat Hmu Hmu, and he had retro fitted it 
with twin Honda 150s, mounted under the bridge deck maybe 20' fwd of the 
transoms.  The pods would lower, as well as the outboards themselves, 
allowing good clearance when up, and close enough to the fore and aft center 
to minimize cavitation due to pitching.  This set up powered a much heavier 
boat over 10 knots in moderate chop with ease.  Hope this helps.

Dave


>From: "Bill Gibbs" <BillG at GibbsCAM.com>
>Reply-To: Informed discussion of multihull issues 
><multihulls at steamradio.com>
>To: "'Informed discussion of multihull issues'" <multihulls at steamradio.com>
>Subject: Re: [MHml] engine power
>Date: Thu, 8 Feb 2007 07:32:50 -0800
>
>Discourage?
>Hardly.  I kind of plucked 20 knots out of the air as an "ideal".  If we 
>only got to 15 we'd be twice as fast, which is not trivial.
>
>Of course the design challenges are non-trivial as well, and I do not have 
>one I am ready to spend money on, yet.  But I am learning
>a lot about powerboat issues.  I'm not so concerned about the power 
>requirements of punching into big seas, as I am about trying to
>visualize the thrust alignment of a hinged "pusher" as the couple goes over 
>big waves, or how to keep AB's bow loaded "down" into
>head seas.  Here 6-7 knots is twice our current speed in these conditions.
>
>Thanks for all the input and ideas.
>Now back to the spreadsheets and CAD files.
>Bill
>
>-----Original Message-----
>From: multihulls-bounces at steamradio.com 
>[mailto:multihulls-bounces at steamradio.com] On Behalf Of Martin Schöön
>Sent: Thursday, February 08, 2007 4:18 AM
>To: Informed discussion of multihull issues
>Subject: Re: [MHml] engine power
>
>On 2/7/07, Dave Culp <dave at kiteship.com> wrote:
> > I suspect a fairly major issue for Bill's application, hard to model,
> > concerns his need to spend much of his powered voyage punching into head
> > seas and head winds.
>...snip...
>
>I sort of hope that my number crunching would discourage Bill  by
>showing how much power he needs to reach 20 knots even on a calm day.
> >
>...snip...
>
>--
>Martin Schöön              "Problems worthy of attack
>                                          prove their worth by hitting 
>back"
>                                          Piet Hein
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