Why are smaller outboard motors water-cooled?



I am thinking 5 - 9 HP engines.



I understand why inboard, inboard/outboard, and larger outboards are
water-cooled; but why are smaller outboard engines water-cooled as well?



Wouldn't air-cooling be simpler?

"Jim Newell" wrote in message
...
Why are smaller outboard motors water-cooled?



I am thinking 5 - 9 HP engines.



I understand why inboard, inboard/outboard, and larger outboards are
water-cooled; but why are smaller outboard engines water-cooled as well?



Wouldn't air-cooling be simpler?


I think existing design is the biggest reason. Outboard motor design hasn't
(at it's core) changed a whole lot in 70 or 80 years. The 2 glaring things
which dictated water cooling that pop out to me are;

1) weight. Air cooling requires fins. Until (relatively) recently, those
fins would have been a weight restriction.

2) noise. The added covering (while lower weight than fins) reduces noise.

I guess a 3rd thing is the instant access to all that cool water is another
influence. No issues with airflow, just scoop some cool water up and run it
down over the parts that house moving parts.

Ed

Jim Newell wrote:

Why are smaller outboard motors water-cooled?

I am thinking 5 - 9 HP engines.

I understand why inboard, inboard/outboard, and larger outboards are
water-cooled; but why are smaller outboard engines water-cooled as well?

Wouldn't air-cooling be simpler?

Simpler, yes, but not my much - outboard water pumps are pretty simple
IME. And air cooled engines are nowhere near as efficient. Air cooled
engines are forced to run richer to maintain low enough combustion
temperatures under heavy loads and high ambient temps. More fuel use,
more emissions. Sitting out on the water, why *wouldn't* you water cool
an engine?

Keith Hughes

Keith,

.....why *wouldn't* you water cool an engine?

Good question, and the answer is that my original question ultimatley ends
up trying to answer the bigger question.....

With boat motors, even small ones costing so much money, why are there not
more conversions out there running an older functional lower unit, and some
sort of lawn/vertical Briggs or Techumse engine.

.....I know that over time, this question has been beat to death! ....but
there is always a "catch" in life, and the motor is becomming the "catch" in
this case that cuts me out of participation.



"Keith Hughes" wrote in message
news


Jim Newell wrote:

Why are smaller outboard motors water-cooled?

I am thinking 5 - 9 HP engines.

I understand why inboard, inboard/outboard, and larger outboards are
water-cooled; but why are smaller outboard engines water-cooled as well?

Wouldn't air-cooling be simpler?

Simpler, yes, but not my much - outboard water pumps are pretty simple
IME. And air cooled engines are nowhere near as efficient. Air cooled
engines are forced to run richer to maintain low enough combustion
temperatures under heavy loads and high ambient temps. More fuel use, more
emissions. Sitting out on the water, why *wouldn't* you water cool an
engine?

Keith Hughes

I was around when a lot of small outboards were air cooled. The
disadvantage can be summarized in one word.....NOISE. The water in the
exhaust helps to quiet the bark of the combustion.

On Thu, 12 Jan 2006 22:32:13 GMT, "Jim Newell"
wrote:

....I know that over time, this question has been beat to death! ....but
there is always a "catch" in life, and the motor is becomming the "catch" in
this case that cuts me out of participation.

================

There are lots of used outboards out there for reasonable prices.

And then there is rec.boats.paddle, totally free, very enviro friendly
and good excercise.

Air cooled motor conversions are an abomination: Noisy, no rust
resistance and vibration.

Jim,

Keith,

.....why *wouldn't* you water cool an engine?


Good question, and the answer is that my original question ultimatley ends
up trying to answer the bigger question.....

But the 'bigger question' seems to be "why not use a gas guzzling, high
polluting, incredibly noisy engine with questionable reliability since
the *initial* cost is lower?". The *only* thing the old air cooled
outboards had going for them (and this relates directly to a Briggs or
Tecumseh as well) was lower purchase price.

Back when the world was young, I did some kart and mini-bike racing, and
I've "rebuilt" quite a few Briggs and Tecumseh motors. Unless they've
changed significantly, they are basically disposable in design. Single
piston ring, no rod or wrist-pin bearings, non-sleaveable
non-replaceable jug, things like that. They would be difficult to
"marine-ize" (adding additional cost as well), and the reliability is
just not there.

As someone else posted, look for a deal on a used outboard. From a
reliability perspective, you'd be better off with a 10 year old outboard
(with some minor servicing) than you would with a brand new B&S or
Tecumseh conversion. Remember, you still have to have the shaft casing,
waterproof gear box, shafts, propeller, etc., all of which are going to
add more cost than the B&S or Tecumseh itself.

Good luck!

Keith Hughes

"Keith Hughes" wrote in message
...
From a reliability perspective, you'd be better off with a 10 year old
outboard (with some minor servicing) than you would with a brand new B&S
or Tecumseh conversion.

In my experience, you'll do better with a 30-40 year old outboard, not to
mention a 10 year old used engine. Those '60s and '70s Johnsons and
Evinrudes are plenty reliable and parts are available.

Ed

....they are basically disposable in design.

And, that is kind of what I was thinking...odd as it may sound;

I am kind of smarting from a 1985 Force 85 that crapped out. Faced with
$1,300 to $1,500 for the powerhead, it got me to thinking about what it
would take to make something fairly disposable. That is to say...who cares
if I had to replace a $200 engine every two or three years, as compared with
what I am looking at now.

(Obviously, I am looking at something much slower. I was thinking floating
raft almost.)




"Keith Hughes" wrote in message
...
Jim,

Keith,

.....why *wouldn't* you water cool an engine?


Good question, and the answer is that my original question ultimatley
ends up trying to answer the bigger question.....

But the 'bigger question' seems to be "why not use a gas guzzling, high
polluting, incredibly noisy engine with questionable reliability since the
*initial* cost is lower?". The *only* thing the old air cooled outboards
had going for them (and this relates directly to a Briggs or Tecumseh as
well) was lower purchase price.

Back when the world was young, I did some kart and mini-bike racing, and
I've "rebuilt" quite a few Briggs and Tecumseh motors. Unless they've
changed significantly, they are basically disposable in design. Single
piston ring, no rod or wrist-pin bearings, non-sleaveable non-replaceable
jug, things like that. They would be difficult to "marine-ize" (adding
additional cost as well), and the reliability is just not there.

As someone else posted, look for a deal on a used outboard. From a
reliability perspective, you'd be better off with a 10 year old outboard
(with some minor servicing) than you would with a brand new B&S or
Tecumseh conversion. Remember, you still have to have the shaft casing,
waterproof gear box, shafts, propeller, etc., all of which are going to
add more cost than the B&S or Tecumseh itself.

Good luck!

Keith Hughes

And if the disposal time arrives when you're a couple miles from shore?
Oh, and please don't cruise through my marina with that noisemaker,
'cause I'm on the boat to relax :-)

Keith Hughes

Jim Newell wrote:

....they are basically disposable in design.


And, that is kind of what I was thinking...odd as it may sound;

I am kind of smarting from a 1985 Force 85 that crapped out. Faced with
$1,300 to $1,500 for the powerhead, it got me to thinking about what it
would take to make something fairly disposable. That is to say...who cares
if I had to replace a $200 engine every two or three years, as compared with
what I am looking at now.

(Obviously, I am looking at something much slower. I was thinking floating
raft almost.)




"Keith Hughes" wrote in message
...

Jim,


Keith,

.....why *wouldn't* you water cool an engine?


Good question, and the answer is that my original question ultimatley
ends up trying to answer the bigger question.....

But the 'bigger question' seems to be "why not use a gas guzzling, high
polluting, incredibly noisy engine with questionable reliability since the
*initial* cost is lower?". The *only* thing the old air cooled outboards
had going for them (and this relates directly to a Briggs or Tecumseh as
well) was lower purchase price.

Back when the world was young, I did some kart and mini-bike racing, and
I've "rebuilt" quite a few Briggs and Tecumseh motors. Unless they've
changed significantly, they are basically disposable in design. Single
piston ring, no rod or wrist-pin bearings, non-sleaveable non-replaceable
jug, things like that. They would be difficult to "marine-ize" (adding
additional cost as well), and the reliability is just not there.

As someone else posted, look for a deal on a used outboard. From a
reliability perspective, you'd be better off with a 10 year old outboard
(with some minor servicing) than you would with a brand new B&S or
Tecumseh conversion. Remember, you still have to have the shaft casing,
waterproof gear box, shafts, propeller, etc., all of which are going to
add more cost than the B&S or Tecumseh itself.

Good luck!

Keith Hughes