ok, Ive heard this idea brought up before and seen it poo poo'd, but can it
work to some extent?

Ive got a 14' cat that i store next to the beach in sydney harbour and i
like to get out for a sail when i can. Unlike most cats this size, it has
heaps of flotation - 3-4 adults and still not sinking anywhere near as much
as a hobie 14 with 2 POB. It has an outboard bracket on the back which was
on it from the factory, but i've destroyed 2 admittedly cheap and nasty
second hand outboards on it so far. I have a new honda 2hp 4 stroke on my
dinghy that i dont want to put on the cat because it would probably suffer a
similar fate.

What happens is that because your moving so fast, the outboard gets
completely drowned, as do the people sailing for that matter ;-) an
outboard might work on a lake or something, but sydney harbour gets choppy.
The thing is, this boat was designed for island hopping the whitsundays and
the manufacturer claims enough flotation for 4 people, plus camping gear, a
stove, and food and water for a week! I cant see how they get the outboard
to survive...

i do ok if i get the outboard started and there are no waves and i just
motor round on it. a 2 or 3 is plenty to move along. its rated for a 5 at
maximum. the trouble is, as soon as you sail if there's a bit of chop, that
motor is getting a drink - then you'll never get it started. I want a bit
of propulsion for getting into some of the finnicky bay areas rather than
spending a couple of hours tacking to death, 5 minutes of propulsion would
get me there. propulsion would also be nice for getting back in if the wind
dies, and finally as a backup just in case something breaks. i like to go
out when the wind is big, and ive already had a couple of incidents with
snapping a gooseneck fitting, and destoying a couple of jib cleats.

so here's what im thinking; a 1250GPH bilge pump in each hull, intake hoses
going into the water, outlets hooked up to hoses facing rear. these draw 5A
each and are cheap to buy. A 40-50AH sealed gel cell would give me a lot
more power than i need. I cant see myself using ot for longer than about 30
minutes to an hour at a time. Is this going to move me at all? at least
more than trying to paddle the boat by myself (which gets me almost
nowhere!) would i get any benefit from using smaller diameter hoses to
create a stronget 'jet', or am i just unnecessarily loading the pump for no
real gain? am i miles off in the GPH stakes.... do i need a lot more
pumping to get any effect?

im not looking for a speed boat here, just *movement* even 1 knot would be
something. benefits to this system are that its fully submersible,
completely unobtrusive, almost silent, would cost me about $100, starts
instantly when i need it.

thanks,
Shaun