G'Day Paul,
  I have a little old Hamilton Colorado Junior jet unit in a 16'
  "Lewis" hull. I've been puzzling over whether or not a P port
  rotary would have enough torque at low revs to spin it, if so
  how about a single rotor, as it's only meant to absorb 100 hp.
  All the published torque curves I've seen seem to show little
  torque below 3000 rpm.

  I have enough 13B parts to experiment in a boat before I try to
  fly on one. It would be an ideal test-bed to play with ignitions
  and carburettors. I flew for many years on a VW using an
  outboard motor fly-wheel alternator to charge the battery. I
  didn't try to use the outboard ignition. I think it was a
  Mercury.

  John Evans

  If it is a jet boat it has a high RPM pump I think.
  16 feet ought to handle the weight of a two rotor. 250 HP would
  really get it going :)

  Paul Lamar



The Berkley and Jacuzzi jet units can be outfitted with impellers that
have different effective pitch. Hamilton pumps might also have
different impellers available for similar reasons.

Matt-

The Chevy V8 units run 4700 RPM max so you might be giving
away some HP unless you can reduce the pitch on the blades
to allow the rotary to rev up to 7500 or so.

Paul Lamar

This is one of my "back-burner " projects I've had for years, it
came to me in a fairly heavy plywood hull which fell apart,it
was powered by a marinised Ford Falcon six cylinder engine of ?
149 cu". It never went very well, perhaps because it wasn't a
very "revvy" engine. I got as far as mounting it in the
fibreglass hull a long time ago and only recently thought of
using it as a testbed for a P port rotary, and as it's only
supposed to have 100 hp I was wondering about a single rotor.

I understand Hamilton do have different pitch impellers and will
investigate that - at this stage I don't know what I've got.. My
main concern was the lack of information on the bottom end of
the rotary's torque curve i.e. would the rotary be able to get
the impeller spinning up to where it has some torque?

                   

Thanks for the input

John Evans

You show go for the two rotor as they are cheaper than a one rotor
Mazda and weight in a boat is not as critical as it is in an airplane.

Paul Lamar