I had a brainwave the other day about putting a small (300cc)
aircooled two stroke as an inboard in a small wooden boat. With
adequate air circulation can anyone see any potential issues here? I
would build the boat with this purpose in mind so adapting something
to fit would not be a problem.

Robin

On Thu, 20 Aug 2009 20:21:25 -0700 (PDT), Robin
wrote:

I had a brainwave the other day about putting a small (300cc)
aircooled two stroke as an inboard in a small wooden boat. With
adequate air circulation can anyone see any potential issues here? I
would build the boat with this purpose in mind so adapting something
to fit would not be a problem.

Robin
Why not?

I assume that you are not talking about a motorcycle engine as if so
you will been to build some sort of fan cooling arrangement.

If you direct drive the propeller you may have a problem with too high
propeller rpm, depending on what sort of engine you are using. In
addition you will have no reverse and again, if it is direct drive, no
neutral.

Depending on your engine and its speed you might want to consider some
form of belt drive which with a little forethought could furnish you
with gear reduction, a reverse and a neutral.
Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

"Robin" wrote in message
...
I had a brainwave the other day about putting a small (300cc)
aircooled two stroke as an inboard in a small wooden boat. With
adequate air circulation can anyone see any potential issues here? I
would build the boat with this purpose in mind so adapting something
to fit would not be a problem.

Isn't an old Vetus an air cooled two stroke marine engine, or am I imagining
some of that? And didn't they do something strange like run backwards and
forwards?

Tim W

"Tim W" wrote in message
om...

"Robin" wrote in message
...
I had a brainwave the other day about putting a small (300cc)
aircooled two stroke as an inboard in a small wooden boat. With
adequate air circulation can anyone see any potential issues here? I
would build the boat with this purpose in mind so adapting something
to fit would not be a problem.

Isn't an old Vetus an air cooled two stroke marine engine, or am I
imagining some of that? And didn't they do something strange like run
backwards and forwards?

No, silly me it was a VIRE two stroke.

Tim w

On Fri, 21 Aug 2009 21:11:56 GMT, "Tim W"
wrote:

Isn't an old Vetus an air cooled two stroke marine engine, or am I imagining
some of that? And didn't they do something strange like run backwards and
forwards?
Not strange.
Steam is nearly dead, for large merchant ships, replaced by direct
drive Diesel. You stop and reset the valve gear, and then restart
turning the other direction. If you are inept at manuvering, you can
run out of the compressed air used to start the engine.

Casady

On Mon, 24 Aug 2009 12:08:53 +0000, Richard Casady wrote:

On Fri, 21 Aug 2009 21:11:56 GMT, "Tim W"
wrote:

Isn't an old Vetus an air cooled two stroke marine engine, or am I
imagining some of that? And didn't they do something strange like run
backwards and forwards?
Not strange.
Steam is nearly dead, for large merchant ships, replaced by direct drive
Diesel. You stop and reset the valve gear, and then restart turning the
other direction. If you are inept at manuvering, you can run out of the
compressed air used to start the engine.


Vintage Washington, Atlas and Enterprise (and others) diesel engines did
this also. They were frequently used in tugs and other medium sized
boats. Not sure if there are any modern midsize diesels which work this
way.

Robin wrote:
I had a brainwave the other day about putting a small (300cc)
aircooled two stroke as an inboard in a small wooden boat. With
adequate air circulation can anyone see any potential issues here? I
would build the boat with this purpose in mind so adapting something
to fit would not be a problem.

Robin

I once sailed on an Olson 30 that had an inboard setup that used a
Tecumseh 2 stroke air cooled engine. I don't remember how they got
enough air circulation.

It was so noisy you had to wear ear plugs.

In article d07591e1-4de8-4e4a-9dca-
,
says...

I had a brainwave the other day about putting a small (300cc)
aircooled two stroke as an inboard in a small wooden boat. With
adequate air circulation can anyone see any potential issues here? I
would build the boat with this purpose in mind so adapting something
to fit would not be a problem.

Robin

Two strokes want to run at one speed... It would be very inefficient in
that situation. Not to mention, unless it was a race boat, the sound
would probably draw gunfire on the local lakes

--
Wafa free since 2009

On Mon, 24 Aug 2009 11:41:40 -0400, JustWait
wrote:

In article d07591e1-4de8-4e4a-9dca-
,
says...

I had a brainwave the other day about putting a small (300cc)
aircooled two stroke as an inboard in a small wooden boat. With
adequate air circulation can anyone see any potential issues here? I
would build the boat with this purpose in mind so adapting something
to fit would not be a problem.

Robin

Two strokes want to run at one speed... It would be very inefficient in
that situation. Not to mention, unless it was a race boat, the sound
would probably draw gunfire on the local lakes

Err - like the Yamaha 250? The one that used to trounce 500 cc
4-strokes in the old days? Even with its tuned pipes it has usable
over several thousand RPM.

Actually it is the tuned exhaust that wants to run at one speed. The
old 2-stroke motorcycles - Famous James, et al, were happy to run over
a fairly broad range. (So is my 2-stroke outboard :-)

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

"Robin" wrote in message
...
I had a brainwave the other day about putting a small (300cc)
aircooled two stroke as an inboard in a small wooden boat. With
adequate air circulation can anyone see any potential issues here? I
would build the boat with this purpose in mind so adapting something
to fit would not be a problem.

Robin

Until the early '60s, lawnmower conversions, both 2-stroke and 4-stroke,
were used in small boats. I fished from one here in Barnegat Bay in the
mid-'50s.

Vertical-shaft motors were used with a commercial conversion unit that was
like the bottom end of an outboard. That provided the gearing for
shaft-speed reduction and it turned the drive axis around. Motors were
typically mounted on a small platform six inches or so off of the boat's
hull so cooling air could get out from under them.

Horizontal-shaft motors used a regular shaft log and packing. They leaked if
you looked at them sideways. Better packing is available now.

These motors, of course, have built-in flywheel cooling fans. They were
noisy; the boats were slow and the two-strokes would gag you if you didn't
use a high exhaust pipe, which was hard to support. Rigging an underwater
exhaust would be a problem. Because you had to leave them fairly open to
cool, their ignition wiring was vulnerable to water splashing in the boat.
(This is one reason that the Acadia and other make-and-break inboards used
low-tension ignition).

All in all, they weren't very satisfactory. But they were cheap. The last ad
I saw for the vertical-shaft lower units would have been around 1962 or so,
but maybe someone still makes them in a dark corner somewhere. There were
some conversions that used scrapped bottom ends from outboards, but I don't
know how successful they were.

Back in the mid-'60s one of the mechanic's magazines had plans for a nifty
little three-point hydro (about the size of a C hydro) with two go-cart
motors powering it through direct shaft drives. There were no fans on the
motors. I don't know how well they worked out, but they were said to do 60
mph.

Good luck. You're not likely to do much better than those old lawnmower
conversions, but it could be fun trying.

--
Ed Huntress