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Old Jul 22, 2009, 12:47 PM
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That's good Schrott and the elbow will be schedule 40 while The rest of the tunnel can be schedule 120 which is much lighter. I'll have to stick one together and see what it looks like. Pete
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Old Jul 22, 2009, 08:13 PM
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So I stuck one together and this is what I got. I'm working on the premise that the prop pushes the water out through the tube,the water pushes against other water and thus propels the boat along. To back up I would reverse the props which would push the water in the other direction against other water and propel the boat backwards. The rudders of course will steer the boat where It's supposed to go. The tunnels will be below the water completly so no air or cavitation will occure. Hopefully. Also I think I will put the next size brass tubing over the tubing shown here to strengthen the shaft and keep any vibration to a minimum.

So do you think I'm on the right track? I will be happy to hear whatever anyone has to say. So far the cash outlay for this boat is $2.38. Pete
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Last edited by norgale; Aug 14, 2009 at 08:23 PM.
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Old Jul 23, 2009, 09:20 AM
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Fine work, great step-by-step discussions, excellent photos. Keep 'em coming, please.

Cheers,
Capt. Spaulding
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Old Jul 23, 2009, 10:10 AM
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Last thing I did was hook the shaft to my drill motor and put the tunnel in the sink full of water. It ran the way I thought it would but it's going to need some high RPM's to run right. Have to rethink my motors now. Pete
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Old Jul 23, 2009, 03:01 PM
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norgale, are you going to put rudders behind the boat in the waterflow of the jetwash?
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Old Jul 25, 2009, 10:45 AM
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What motor size???

Yes I am ghost. I havn't made the rudders yet but they will be about 3/4" wide and maybe 1-1/2" long and will be right in the water flow. My problem now is that I may have made the tunnels too big. I wanted to use the props I already had and they are 1-1/8" (these props are 1" I find now)so that's what I went with. However now I need to get some motors for the drives and don't really know what to get. The drives need to be pretty high RPM's so can anyone recommend a proper motor for this application? Prolly want to keep with 12 volt and the shafts are 1/8th inch. I think I made this thing too big. Pete
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Old Jul 25, 2009, 02:42 PM
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graupner speed600 would be a nice one. you also want plenty of low down torque, as you will get some compression anyway. reversing is going to be interesting as you will be jetting water down. may I sugest you add scoops to the bottom, this will when you shove it in to reverse force water horizontally and not down, otherwise if you give it the beans in reverse your arse end will come out of the water and sound like a cavitating blender
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Old Jul 25, 2009, 02:48 PM
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Scoops on the bottom will also help channel water into the tunnels when going forward. I can only imagine that this would give your boat more thrust.

Massey
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Old Jul 25, 2009, 04:09 PM
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it may also reduce the vertical suction effect as well, so rather than being sucked down, the boat will actually be sucked horizontally. A rather crazy idea would be to if possible, have them swivelable, so when in reverse you have steerage
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Old Jul 25, 2009, 04:38 PM
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Actually Ghost ..a bucket over the outlet thats swept down over the nozzele would allow the motor to keep turning one way ..but re-direct the water to allow reverse ..similar to a jet drive..
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Old Jul 25, 2009, 05:41 PM
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more coffee, Norgale is putting rudders behind the jets as opposed to directable nozzles
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Old Jul 25, 2009, 06:01 PM
Kraut
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I like the scoop idea, but I would not swivel them, I would extend the rooder down and have part of go along the bottom of the hull towards the scoops.

gue
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Old Jul 25, 2009, 08:28 PM
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Good thinking Ghost and the actual reverse thrust will be back out the tunnel at a 120 degree angle so it will push some against the forward motion. And yes I'll need some decent torque but what do you mean by "compression"? Do you happen to know what the RPM's are for the 600? I have to look it up anyway so I'll find it.
Hadn't thought about the stern rising up. That would be interesting. Don't want scoops as that would present another problem of drag. Swiveling I was avoiding because of the engineering and fabricating that goes with that. No reversing buckets for the same reason. Rudders are much simpler and easier to build.
I have to "kiss" this thing as much as I can. (Keep it simple stupid)
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Old Jul 26, 2009, 02:09 AM
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the scoops wont put any more drag than rudders, but your current set up will give you a lot of vertical suction and with no reversing buckets on, you have no reverse, as you will lift the stern up out of the water in reverse.
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Old Jul 26, 2009, 02:40 AM
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That shouldn't suck the boat down any more than a standard jet drive setup would? Reverse might be interesting, might still be fun to try it though...
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