CAUTION: Metal boat stuff advice sought

Greetings All, I have a 12 foot aluminum boat that is rated for a 10 HP max motor. I do have a 10 hp outboard but bone on bone joints in both wrists makes it really painful to put the motor on. For years I have been thinking about various schemes to put in a liquid cooled 4 stroke inboard. One idea is to use a conventional air cooled flat head motor that's been modified with a water jacket. I told Harold Vordos about this idea and he had done it and it worked well. I mean the liquid cooling conversion. He even had done it with a motor that was very close to a 7 hp motor that I have and was considering. I have also thought about using a 125 to 250 cc motorcycle motor. But these are expensive and rev higher. I have several reasons for wanting to do this project. Mostly I want a quiet power plant and a liquid cooled engine inside some sort of housing seems like it would fit the bill. I want 4 stroke mainly because I'm tired of putting oil in the water. I also want reverse and am not sure what is the best way, at least for me. The plan is to use a prop shaft that pierces the bottom of the boat and a rudder. So the motor would be inboard as would the reversing gear. Money is tight so don't suggest a Crosley engine. If I could even find one for sale. Any thoughts? Thanks, Eric

Reply to
etpm
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One idea is to use a conventional air cooled flat head motor

. I

I would not include the reverse at least at first. You could probably add a brake to the boat fairly easily. Sailboat do not have a reverse and it is not that big a deal. You just always approach the dock from the down wind side.

Dan

Reply to
dcaster

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Greetings All, I have a 12 foot aluminum boat that is rated for a 10 HP max motor. I do have a 10 hp outboard but bone on bone joints in both wrists makes it really painful to put the motor on. For years I have been thinking about various schemes to put in a liquid cooled 4 stroke inboard. One idea is to use a conventional air cooled flat head motor that's been modified with a water jacket. I told Harold Vordos about this idea and he had done it and it worked well. I mean the liquid cooling conversion. He even had done it with a motor that was very close to a 7 hp motor that I have and was considering. I have also thought about using a 125 to 250 cc motorcycle motor. But these are expensive and rev higher. I have several reasons for wanting to do this project. Mostly I want a quiet power plant and a liquid cooled engine inside some sort of housing seems like it would fit the bill. I want 4 stroke mainly because I'm tired of putting oil in the water. I also want reverse and am not sure what is the best way, at least for me. The plan is to use a prop shaft that pierces the bottom of the boat and a rudder. So the motor would be inboard as would the reversing gear. Money is tight so don't suggest a Crosley engine. If I could even find one for sale. Any thoughts? Thanks, Eric

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Many decades ago, single-cylinder inboards were used for some small fishing and utility boats here in NJ. Horizontal-shaft motors typically used a conventional shaft log, packed with tarred rope at the ends and made of two planks screwed together. Vertical-shaft motors used a through-hull gasket and a right-angle powerhead that looked like the bottom-end unit of an outboard. In fact, that's what some of them were. The shaft-log types didn't have reverse, IIRC, but at least some of the through-hole vertical-shaft units did.

'Don't know about cooling conversions. Most were air-cooled mower engines and the like. Exhaust stacks went straight up around five feet. An underwater exhaust is quieter, but not easy to implement.

Good luck. If you can pick up a cheap or free outboard with a shot motor, most of your work is done.

Reply to
Ed Huntress

Well if you have the skills to fab a water jacket then the only other big hurdle would seem to be how to handle reverse. Instead of a gear box why not a kitchen rudder?

Reply to
Monkey Butler

I could even hack the 10 hp merc I already have or an old 5 hp that I have but these are 2 stroke motors. I don't want to dump any more oil in the water. I thought about using the lower unit from an outboard with the reverse built in and just rotating for reverse or using a plain lower unit and rotating 180 degrees for reverse. However, I like the idea of a straight shaft and a rudder. And reverse is important to me. I have three outboards and the big one has reverse while the small ones just rotate 360 degrees. I like reversing. It really helps a lot when it's just me in the boat. which is most of the time. Eric

Reply to
etpm

Well, the thought is that you would use the outboard bottom end and a four-stroke motor, so the condition of the two-stoke wouldn't matter.

Those vertical-shaft conversions I mentioned did not rotate. If they had reverse, it was a gear reverse in the lower unit. Some of the old ones, and maybe those made today (I haven't looked) just shifted the pinion shaft from one side of the bevel gear to the other with a fork. The pinion slid on a splined shaft.

Regarding cooling, there have been all sorts of arrangements on old outboards. I had a British Seagull outboard that had a water-cooled cylinder and an air-cooled head.

Reply to
Ed Huntress

I mis-read your post ED. Your were talking about using the lower end and somehow I read that you meant the motor. Oops. About weird cooling, my neighbor had an outboard that cooled the exhaust with water and the engine with air. Eric

Reply to
etpm

What is a kitchen rudder? Thanks, Eric

Reply to
etpm

Greetings MB, Never mind, Google provided the answer. That's a cool idea. I like it. Thanks, Eric

Reply to
etpm

What you're looking for is basically a work boat design. I ran a 14' hull with a home brewed straight shaft with a variable pitch prop. It allows you to adjust the speed and direction without changing the engine rpms. Engine was a 16 HP Briggs twin from a Cub Cadet tractor. Even used the factory engine plate because the engine sets at an angle already. Air cooled and exhaust ran out through a car muffler and out the transom. Built a tower in the middle that covered the engine, held the prop direction and steering controls for the rudder. The prop came from an outfit called Marine Propeller. Not super fast but it worked well enough. I have since replaced the entire boat with a 15 foot bass tracker that was a salvage hull.

this one uses a similar prop but a 5 horse engine

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Reply to
Steve W.

Glad you like it. Let me know if you ever build it.

Reply to
Monkey Butler

I will. Maybe not so easy to design. I've been thinking about the curve of the parts and how to use the thing for steering and reversing. Actually kind of complex linkages involved. Eric

Reply to
etpm

Befriend a healthy young lady who likes to fish and can handle the outboard.

And, maybe, get a smaller motor. My 9.9 Yamaha is 95 pounds dry.

But for the adaptation of an air cooled engine to liquid cooling - and installing it in a 12 foot boat??? on a tight budget?

I'd have to say the years scheming about it could have been better used _trying_ it.

OR?

A very good troll....

Reply to
Richard

Not that complex - just a mechanical mixer.

Here is one...

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ANOTHER
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The best diagram, I think, is from this Avro Vulcan page...

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(hey, if it works?)

Reply to
Richard

Eric, a small three blade CPP design isn't that hard to make up if you have a mill or access to a shop.

Basically you have three blades, these get connected to the hub with a rotating collar. The collar transmits the thrust to the hub. Inside the hub you have what amounts to eccentric levers. These connect to the collar and by simply pushing/pulling the rod you control the angle of the blades.

The one I had used a 1 1/2" shaft diameter with a 1/2" rod inside it. The shaft was turned with a simple twin sprocket on the outside. The adjuster stuck out the front of the shaft with a lever attached.

Reply to
Steve W.

You can use any liquid cooled engine and build a keel cooler - just a loop of water pipe mounted parallel with the bottom of the boat. an inlet and outlet flange attached to the boat and a small header tank. You will likely be able to use the engines normal water pump to circulate the coolant. Reverse does present a problem but if you can make a bracket to hold two gears with a vee belt pulley on each gear that could be used to reverse a belt driven prop shaft.

Ot just use an air cooled engine and put a wire box over it to keep body parts from coming into contact with hot engine parts.

Or maybe a "long tail motor". See

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for photos. Although a long tail doesn't have a true reverse you can go backwards, a little slouch-wise but generally toward the back end.

One thing about a long tail you can use any engine you want, from an old lawn mower engine to Oh-My-God-Thats-a-Big-One.

But truly, converting a 12 ft. outboard boat is going to be somewhat of an exercise in frustration. The inboard and its engine mounts and auxiliary parts is going to weigh more then the outboard did and because the hull was designed to support the engine on the transom moving the weight forward may well alter the way the boat sits in the water.. Unless you build a water cooled exhaust you have the hot exhaust to contend with.

Anothr thing to think about is whether you really, really, need a reverse. I use a direct drive outboard on my dinghy and while I can reverse by turning the engine around backwards I rarely do.. There is no neutral either, pull the rope and go. A pretty primitive setup but there are a lot of them around.

-- John B.

Reply to
John B.

Steve, Got any pictures or drawings? I thought about something like that and looked at buying a used one. Very pricey. But maybe really fun to build. And I have the tools to make one. But making the blades would be tough to program. Eric

Reply to
etpm

Richard, I've been busy with other more important things. And I've been using the boat but my wrist pain has finally gotten to the point that I need to do something. Eric

Reply to
etpm

The blades are actually easy. Because you can adjust the pitch on the fly they don't have to be real complex.

Some good info.

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Controllable pitch propeller on you tube shows a bunch of animated rough ideas.

The interior of the one I had was nothing more than three eccentrics with pins that engaged the collar. The collar was round and made of hardened steel.

Basically it looks like a helicopter collective but internal.

If you want to see one up close there are some made for model aircraft and model boats.

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simple version
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Reply to
Steve W.

Take Tylenol and Naproxin together. They work symbiotically and it should help at least some.

As for the boat, from what I saw of the floating lawn mower, a healthy trolling motor could probably give it a good run for the money and effort.

Or perhaps a Honda 2 HP outboard? Pricy new, but can occassionally be found used. 29 pounds. I've been saving up to buy one for my dinghy.

Reply to
Richard

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