[MHml] horsepower & sleds

[Diane Selkirk]

Pushing is usually more efficient than towing because (believe it or not) the drag of the towrope gets significant.

What you want is one of these RIBS

http://www.cromptonmarine.com/gallery/large/15msearanger5x250-1.jpg
;)

A beachcat won't have the buoyancy to support a big outboard and will squat so much it will sink the sterns under.

A big planing plywood skiff or RIB pushing on the aft beam is the best bet if Bill is serious.  The tricky bit is pushing in seas.  The stresses on the connection point will roughly = weight of the push boat +/- 20%.  Once you get going with a prop tuned for 20 knots all is well (accelerating slowly) but if you hit a big wave and you slow to 8 knots then somebody has to back off the throttle fast to prevent the prop cavitating and slowly accelerate the boat back up speed.

It's not a trivial problem.  My suggestion:  find a big RIB and get them to tow you (much simpler for a trial) on a day with some big waves and see what sort of speed you get with X HP.

Evan Gatehouse