Since the original idea was to use the engine off a 'cycle that was
"totalled", is it possible to find a wrecked jetski, buy it with the
salvage tag, then strip it for your larger boat? snip

Or, (to play devil's advocate) are jet ski mishaps "just total
write-offs", and not worth trying to salvage (due to submersion, etc)?


Sort of like http://www.glen-l.com/jetski/jetjon-index.html ?

There used to be a jetjon site dedicated to using old jetski powerplants in
bigger boats, but it seems to be defunct...

On Mon, 07 Feb 2005 20:41:30 GMT, ewan wrote:

this is more of a theoretical question more than anything else but a
couple of mates and i were chatting about boat building and engines in
general.

basicly ive heard a lot of engines are based upon marinised car
engine based but i got to thinking how simple it would be to use a shaft
drive bike engine {1} since theres a wide range of shaft drive engines
from 550s to 1100cc especialy the 900cc yamaha diversion engine which is
dirt cheap. i know the engines wouldnt last as long but sing they start at
£80 from breakers{2} means it could be treated as disposable item like
petrol.

im just posting to see if there is any serious flaws in the idea such as
not enough torque or other variables



{1} i guess i would have to work out the forces and calculate propeller
assuming the revs arent to high

{2} breakers tend to sell all the stuff that breaks in a crash like
plastic and bits that rust leaving them with the engine which most folk
dont want to replace

I will kick the idea around a little - if you wish.

I hear that one engine fitted in a Harley comes from the Ford [KIA]
Festiva - this is a water-cooled 1.3 liter engine - it's a good one,
no doubt.

This is a free-reving, spritely compact-car engine.
It uses electronic engine control - one secret of auto engine
longevity these days .... a lean engine is a clean engine ....

A sensible gear box that can take plenty of thrust is a requirement.
But the self contained water-cooling avoids the salt I guess.
Or how about an air cooled engine?
Loud, needs cooling
Auto engines are not the best at slogging hour after hour. (That's
when you need an egine - the mast or sails have given up...)

Brian W

On Mon, 07 Feb 2005 20:41:30 GMT, ewan vaguely
proposed a theory
.......and in reply I say!:

remove ns from my header address to reply via email

IMO, unless the boat is small and fast (rapidly up on plane), and the
engine is exposed to the air (noise), you will have troubles. Boat
engines are made to either slog, or have plenty of cooling to allow
for the hard yakka. Bike engines are made to flow freely, and usually
the harder they really work (that's grunt, not revs) the more air is
flowing over them. This would apply even to wayter-cooled ones, where
fins are simply replaced by the radiator unit, which needs its own air
flow.

I suppose you could use a huge belt-drive fan, a la cars/trucks. More
power gone. More noise.

You can get gearing to allow for the rev problems. As somebody said, a
bike has a gearbox. You could proably get something to work, or even
"change gears". You can put in any number of bearings to allow for
thrust problems. You can put in fans to remove fuel vapours (although
an engine stuck up in the air is not going to be so bad here) But how
far do you go.

Basically, bike and VW engines are used for _planes_, not boats. They
are lightweight for power, and thrive on lighter loads and/or good
airflow.

this is more of a theoretical question more than anything else but a
couple of mates and i were chatting about boat building and engines in
general.

basicly ive heard a lot of engines are based upon marinised car
engine based but i got to thinking how simple it would be to use a shaft

As far as I know, marine internal combustion engine needs:

1. Ouboard water heat exchanger for engine coolant,
2. Engine sump water coil or oil heat exchanger for oil cooling,
3. Engine exhaust manifold with cooling jacket,
4. Exhaust cooling by water injection and water ingestion blockage by proper
exhaust elbow,
5. Water jacket for cooling marine gearbox and propeller shaft thrust
bearing,
6. Proper self priming outboard water pump supplying above circuits.

A propeller driven Florida Swamp Airboat is the only boat without these
items!

Regards, Tadeusz

I've noticed a few ads in "Ducks Unlimited" magazine for Harley-Davidson
Evolution engines in duck hunting boats (shallow draft john boats, like
Polar-Craft) using the far east style long shaft open prop. Several U.S.
manufacturers. Anyone out there got a Ducks Unlimited mag handy to give an
address? I don't have one. I saw the mag in a hospital waiting room a
year ago. They looked well made and were expensive, knowing how
$$$Harleys$$ are. You could steal ideas from the ads. Seems I remember the
were using 4 blade chopper props for working in weeds and muddy waters.
Good luck.
"ewan" wrote in message
news
this is more of a theoretical question more than anything else but a
couple of mates and i were chatting about boat building and engines in
general.

basicly ive heard a lot of engines are based upon marinised car
engine based but i got to thinking how simple it would be to use a shaft
drive bike engine {1} since theres a wide range of shaft drive engines
from 550s to 1100cc especialy the 900cc yamaha diversion engine which is
dirt cheap. i know the engines wouldnt last as long but sing they start at
£80 from breakers{2} means it could be treated as disposable item like
petrol.

im just posting to see if there is any serious flaws in the idea such as
not enough torque or other variables



{1} i guess i would have to work out the forces and calculate propeller
assuming the revs arent to high

{2} breakers tend to sell all the stuff that breaks in a crash like
plastic and bits that rust leaving them with the engine which most folk
dont want to replace