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Re: homemade outboard

well, I looked over your latest few pictures and ya know,, that is almost actualy starting to look like a outboard hehehe.

Problems Problems,, Lets see here.. Faces with your current problem. Drilling steel, well, you should actualy have 2 maybe 3 bits of different sizes ( small to the size you need ) and use them acordingly when trying to make a hole that big in stock like you are using. I would also recomend using a med weight oil, well, actualy any oil will work, but I would stop and oil the hole every so often when drilling. As Far as using a torch, I could pop a hole nice and neat in that metal that would require minimal grinding to make neat neat, howver, I think you will probably end up drilling it. it dosent appear your welder could cut through it. Speaking of your welder, If it is overheating like you say,, I would take some pliers and open up all the slanted air vents in it to allow for better air flow. MIght even go as far as to actuly cut a hole in it and install a permant cooking fan,,Anyway,,
I was unaware that you could not spin a chain at 4000 rpm,, Last I knew, Most motorcycles rev up well in excess of 4000 rpm and a good deal of those are chain drive,, anyway,, I dont think stretching will be to much of a problem,, it will stretch out so much and then stay there for its effective life. I am pleased you have given up on trying to create a neutral with the idler pully, But I really dont see the harm in using one to take up belt slack, In fact, I suggest the following, Install 2 additional small pullys, one in the lower unit that is fixed in place, and one at the top that is also fixed, but adjustable. Now, Why the one on the lower unit you ask? well Ill tell ya, the second pully on lower unit is placed in such a position that it forces the belt around more of the pully before allowing it to return up the shaft. this will give more grip and make water and sliping less of a factor. the one on the top will also wrap the top pully in the same fashion, but be adjustable for the purpose of changing the belt, and tentioning it. Yes, You will loose a minimal amount of HP here, but You will never get 2 usefull HP to the prop anyway.
Now the bigest problem. the housing for the lower unit. Failing to locate PVC and not really wanting to use ABS, I have a resonable sugestion or 2 I think. Why not build out of wood? Probably be allot more hydrodynamic.and falling back to a old faviorite, You could probably encase the unit with a truck inertube and some hose clamps. If It were I doing it, I would build the standart L shape, Completely boxing off the vertical shaft on all sides, But on the lower part, I would leave one side open. then I would fiberglass it all around the outside. no more then a half gal of fiberglass resin should do it, probably more like a quart, but I always like to go heavey when fiberglasing,Probably be a good idea to reinforce all the edges with some 2 inch mesh, overlaping 1 inch on each side of every corner, anyway,, after that, I would instal the internals, then close the side panel previously left off with another piece of wood that has also been fiberglassed on one flatside, and all edges. I would use a ruber seal to gasket this, perhaps more intertube ruber, and stainles steel wood screws to hold this "access" panle in place. You would more likely then not want to make another metal bracket that you can bolt onto you woden lower unit allowing a solid conetion to the powerhead that is all metal.
I had another idea too,, about the water getting in from the top, you can probably boot the top ( with more intertube ruber hehehe ) It should not mater if the tube touches the belt, it wont be watertight or anything but should greatly reduce spash water. The belt is gonna get a little wet anyway, No mater what you do, you can only try to minimize it.. Hmm,, I wonder what would happen if instead of sending the exhuast underwater, you used it to dry the belt... well, maybe not, probably isnt worth the noise. Underwater exhust is way quieter. and it would probably reduce belt life.. But I bet it would stay dry hehe. ow well, guess Ive given you enough to think about this instalment.

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