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
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On Oct 25, 2:16 pm, snipped-for-privacy@whidbey.com wrote:

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
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wrote in message
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
================================================================ 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.
--
Ed Huntress


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On Tue, 25 Oct 2011 15:24:32 -0400, "Ed Huntress"

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
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wrote in message

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. <g>
--
Ed Huntress


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On Tue, 25 Oct 2011 16:25:05 -0400, "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
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On Oct 25, 2:16 pm, snipped-for-privacy@whidbey.com wrote:

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?
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On Tue, 25 Oct 2011 12:49:06 -0700 (PDT), Monkey Butler

What is a kitchen rudder? Thanks, Eric
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On Tue, 25 Oct 2011 12:49:06 -0700 (PDT), Monkey Butler

Greetings MB, Never mind, Google provided the answer. That's a cool idea. I like it. Thanks, Eric
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On Oct 25, 5:30 pm, snipped-for-privacy@whidbey.com wrote:

Glad you like it. Let me know if you ever build it.
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On Tue, 25 Oct 2011 17:57:35 -0700 (PDT), 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
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On 10/25/2011 9:14 PM, snipped-for-privacy@whidbey.com wrote:

Not that complex - just a mechanical mixer.
Here is one... http://shop.dubro.com/products/productdetail/V-Tail+Mixer+%28QTY/PKG%3A+1+%29/part_number !5/101.0.1.1.5161.5191.0.0.0?pp&#
ANOTHER
http://www.homebuiltairplanes.com/forums/attachments/sale-wanted/12481d1305918642-v-tail-bonanza-ruddervator-control-mixer-diagram-iphoto.jpg
The best diagram, I think, is from this Avro Vulcan page... http://www.pistonheads.com/gassing/topic.asp?t †0445 (hey, if it works?)
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snipped-for-privacy@whidbey.com wrote:

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.
--
Steve W.

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wrote:

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
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snipped-for-privacy@whidbey.com wrote:

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.
http://www.boatdesign.net/forums/props/controllable-pitch-propeller-summary-30695.html
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.
http://www.youtube.com/watch?v=FT8gzQNCwGk&feature=related
http://aircraft-world.com/prod_datasheets/al/trex600-ESP-BLUE/trex600-ESP-BLUE.htm
simple version
http://www.youtube.com/user/juicepop2005#p/u/2/uTOJEP8jIGA

--
Steve W.

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wrote:

Thanks for the info Steve. Lots of good stuff like you said. Can the blades really be that simple and work well? I mean, can flat blades resembling ping pong paddles really work well? I've read a couple books about propellers, fixed blade types, for boats, and even used the info with a pitch block to change slightly the pitch on a bronze prop in an effort to get it to work better with an antique outboard motor. But if I can get by with flat paddle shapes then it may be possible for me to make a CPP that actually works well. Eric
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snipped-for-privacy@whidbey.com wrote:

They can be but they won't be as efficient. What you can do is to make them curved more like an airfoil. Take a look at a common fan blade for an idea. You will want to make the root thicker though, far more stress in water than air.
--
Steve W.

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wrote:

I should have been clearer. A boat prop is cupped. What I'm thinking of is a shape like a foil with the curve equal on both sides of the blade but otherwise flat. Is that correct? Another way to describe it would be a teardrop cross section. So if the blade was horizontal and moving through the water it would have equal lift on both sides? Thanks again Steve for the previous links. Lots of food for thought. Eric
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snipped-for-privacy@whidbey.com wrote:

Teardrop would work but not very well. Now if you make the front side curved but the back side flat or even slightly cupped you would get more thrust. With a CNC or a good template it wouldn't be that difficult to make.
--
Steve W.

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SNIP

So I make the part like you describe above, which I can do, but still make the blade resemble a ping pong paddle? Or would it be better to make it look more like a normal prop blade? Since reverse doesn't need to be very effiecent it seems that might work best. I obviously need to do some more reading. Eric
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