[MHml] engine power

[Dave Culp]

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. Winds aren't so hard to model (though not trivial; AB's
rig has lots of wires), but hobby-horsing over and punching through head
seas is not only uncomfortable and power-absorbing, it must be the devil to
model. It may even be that the lighter hull will suffer more degradation (of
performance) than a heavier hull would.

Can Michelet model this?

Dave

On 2/7/07, Martin Schöön <martin.schoon at gmail.com> wrote:
>
> On 2/6/07, Tim Bell <tim.bell at brightwater.co.nz> wrote:
> > Further to my earlier post, I know of two Malcolm Tennant design ferries
> > operating in NZ that cruise at 24knots with 2 x 300HP John Deere engines
> > (because they are skinny and fit into the narrow hulls). The ferries are
> > about 55ft long, one operates on Wellington Harbour every day, and the
> > other now operates in Marlborough Sounds from Picton. The hulls are not
> > too dissimilar to Afterburners, probably a bit fatter and have the
> > Tennant taper underwater to the propeller with horizontal surface at the
> > water line to avoid squatting.
> >
> > Malcolm once told me that he thought AB's hull speed was over 20kn,
> > around 24-25, so planing is not an issue here.
> >
> > Gives you an idea on how much HP the sails develop to pull AB along at
> > 25kn.
> >
> I just took a quick look at Tennant's commercial cats on his web and
> they are all
> at least twice as heavy per length as AB is. Also operational speed is
> usually
> stated and I assume there must be some power excess to stay on schedule
> when conditions are not ideal - how much extra power?
>
> I will see if I can model one of them this weekend (time permitting).
>
> --
> Martin Schöön              "Problems worthy of attack
>                                          prove their worth by hitting
> back"
>                                          Piet Hein
> _______________________________________________
> Alter your subscription details or unsubscribe at the bottom of this page:
> http://www.steamradio.com/mailman/listinfo/multihulls
>
> Multihulls mailing list      (Multihulls at steamradio.com)
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://steamradio.com/pipermail/multihulls/attachments/20070208/7c7c021b/attachment.htm