[MHml] horsepower & sleds

[Ross Hobson]

Bill
sounds as if you have just described a big RIB (7+m long) with a diesel/petrol inboard and tow afterburner on a bridle
 
Ross

________________________________

From: multihulls-bounces at steamradio.com on behalf of Bill Gibbs
Sent: Thu 01/02/2007 19:28
To: 'Informed discussion of multihull issues'
Subject: Re: [MHml] horsepower & sleds



We have a mounted 20hp Honda in a central pod.  It's a bit of a pain to remove.  It is adequate, though it ventilates in choppy
seas.  We can do 7.5 knots in flat water.  But we lose a lot in a headwind and/or seas.  And our typical return transit is up the
coast into headwinds and seas.  We do sail home on occasion and motor-sail to good effect, with good speeds but reduced VMG for sail
angles.

I'm imagining a trailerable mule boat that will get us over 20 knots.  20 knots VMG on a return transit would be awesome.  6 knots
is our rough overall average VMG combined motoring/sailing/motor-sailing, though this can vary with conditions.

Bill

-----Original Message-----
From: multihulls-bounces at steamradio.com [mailto:multihulls-bounces at steamradio.com] On Behalf Of Ross Hobson
Sent: Thursday, February 01, 2007 10:51 AM
To: Informed discussion of multihull issues
Subject: Re: [MHml] horsepower & sleds

Towing is easier than pushing - but you need weight in the RIB or it will slew all over the place. An easy way is just to flood the
floor , this is necessary when slow manovering and starting off, once up to speed drop the flooded water. Avon Seariders are
excellent in this situation as their hull is designed to flood and empty

for the engine on afterburner:
what about an internal 'trunk' ie a box that lifts out inside one hull that you can drop the outboard into (venting it outside
obviosuly).  the prop will always be in the water.

when you get to destination - lift out engine - drop in 'box' to seal hull and reestablish hull shape- minimal weight if built in
foam/carbon

we used to have this arrangment on Mollymawk and it worked really well - until the rules changed which meant we had to change the
set-up.
How much HP do you need??
10hp pushed Mollymawk at 6-7knots when in it's well and 5-6 knots when mounted aft on a conventional o/boatrd bracket as the engine
was lifted in and out of the water due to pitching
5Hp pushes Charleston at 8knots, -but she is more an overgrown, steroid fed, beachcat

20 or 25hp in an internal set up should allow Afterburner to move easily at 8-10 knots ??

Ross

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