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Old 03-24-2017, 02:59 PM   #141
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Pete,

What Andrew said actually makes sense.

You might find that lots of ballast might be required to get the hull to its waterline (can't say designed waterline because you worked it out yourself), but even so, getting a good waterline is one of the first things you need to do, without it you could end up with a very unstable boat.

I made a 4ft long Clyde puffer, and even with a 100 amp hour battery in it, it was still too top heavy. I eventually put in internally sealed ballast tanks that allowed the boat to sink further, they contained another 5gallons of water weighing 50 pounds.

The chalk marks on the outside of the hull shows the rough position where the tanks were inside.




You might have to resort to having a couple of large pop bottles full of water inside to achieve your waterline.


John


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Old 03-24-2017, 05:04 PM   #142
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Quote:
Originally Posted by apointofview View Post
This is the amount of miss alignment I have. The brass is the snuffing tube and a 3/16 shaft will ride in it.

Pete
I suggest what is known as a "Flex Shaft"

http://1nitrorc.com/sqdrv.htm



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Old 03-24-2017, 11:31 PM   #143
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I appreciate the ideas, and yep it is what I should do. The engine will raise up some because it has been pointed out that this little engine will coat the belly with oil and water as it runs so a catch pan would be wise. It will mount to something so with all that it may be almost lined up. Silly thing is I have the universal setup in my head so for now I am just going to use the tmaxx shaft and then if I like the shaft and hate the plastic I will make a brass version. My next chunk of time is going to be in a prop. I got a quote for the prop and its going to be 40$ so I get to learn how to make the scrap under my bench into a propeller. I found this site - http://members.dodo.com.au/~sjbatche...propellers.htm I like the jig he made so that's what I will do.
I did float the hull again and threw lead car wheel weights in till I hit the shallowest I could go just submerging the prop under the surface and the stability got a lot better. I still have a inch or two to play with for waterline so even more lead can be tossed in. I might put a thick hunk of metal on the bottom for the keel too to protect the wood and that should help.
Pete
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Old 03-24-2017, 11:45 PM   #144
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Pete,

Please try to use removable ballast, something like I suggested. Put boat into water and then add heavy ballast, reverse, for boat removal.

There is nothing worse than trying to lift a very heavy boat in and out of the water, just one slip on a muddy bank soon teaches what you need to do.
DAMHIK as the boat I showed above weighed well over 100 lbs when fully loaded with water in the ballast tanks, and who forgot to drain them before trying to lift it out of the water.
It was autumn as well and the water was freezing and very very wet.

John
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Old Yesterday, 12:57 AM   #145
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Ok, does your boat flood those tanks from the water its sitting in ?
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Old Yesterday, 06:16 AM   #146
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Yes, just open two taps and the tanks fill up from holes in the bottom of the hull once the main battery has been put in, remove battery, open taps and the hull automatically rises and empties it's tanks ready for lifting out of the water.

John
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Old Yesterday, 08:56 PM   #147
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John - Ok I will remember that.

So work is going well on the prop I think. I am not looking for every last bit of thrust from the blades so researching the hydrodynamics of a blade are not on my list of things to do. This just has to putt around on a little pond and not fall apart. I drew out the shape I wanted and then cut out template for the metal. Tin snips cut the rough shape and then I sanded them to the lines traced out on the brass. To get the curve I used a deep well socket and a block of wood cut to the same shape. My vise smashed the two together and out came a curved blade. I wanted to remove a little pitch at the tips so I clamped up the root of the blade and then twisted the tip with another bit of wood that had a curved cut in it to hold the blade. Last was to file the root to conform to the hub which will be around a quarter inch round. Just for fun I superglued the blades together and spun the prop up in my cordless drill in a sink full of water. It seems to move the water pretty well. You can sort of see the spinning blades in the sink and the water pushing up the sides. I tried to spin it about what I expect the engine to turn but it's hard to know that.
Pete
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