On Tue, 08 Feb 2005 12:28:59 GMT, "Keith"
wrote:


http://www.scavengerbackwater.com/scavenger.html
I've even seen folks use little gas powered weed eaters, replacing the
fishing line cutter with a little prop. Noisy, but inexpensive and basically
disposable after a couple of seasons.


I have one of those. It's loud but it works well. Much better than a
battery powered trolling motor. Batteries die quickly but I have went
5 miles on a pint of gas in my canoe. What it really needs is gearing
though. I have worked out a few designs but have not came up with
anything that would be easy to build and would work well. If I could
make that little 2 cycle engine go double the rpm I would have twice
the power and the engine would run better. Little 2 cycles don't like
low rpms.

I got tired of the weedeater engine and converted the canoe into a 4
stroke inboard. Used a 2hp Briggs and Stratton motor. Little canoe
was quite fast in that incarnation. Then I got an old fiberglass
semi-v jon boat with a 15 hp outboard. The canoe sat until the
sawhorses I kept it on collapsed and tiny black ants felt like my
transom was a good home. I may rebuild it again someday. I have
rebuilt that canoe like 10 times in the 15 years I have owned it.

But first I need to build me a new boat. The semi-v is over 40 years
old and the fiberglass acts more and more like it is going to just
give one day. What I need is a method of boat building that doesn't
cost much of anything. I have thought about using cheap materials,
but all the cheap ones will make the boat less safe than the one I
have now. I need to build a 15ft boat that is capable of carrying 6
people for less than $200. Is it possible? Caveat being that is has
to be a safe boat that will last more than one season.

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