| Author |
Message |
    
miro
Senior Member
Username: miro
Post Number: 1070
Registered: 11-2001
| | Posted on Friday, February 28, 2020 - 05:54 pm: | 
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Here's a really good photo of the skeg on a DisPro showing how it works.
When the skeg hits an obstruction, it kicks up the prop , out of the way. The suport bearing slides on the driveshaft as it is turning.
Then after passing over the obstruction, the boatman / boatwoman simply lowers the whole thing back to its normal running position.
The photo was ( obviously ! ) taken last summer by Gary Champaigne when we had liquid , not solid water aka ice , on the lakes.
The original supplier of the flexible joint from 1915 (Gray and Prior) closed shop in Oct 2016. New joints are OK, but not quite as good as the originals.
miro |
narrabay2
Advanced Member
Username: narrabay2
Post Number: 39
Registered: 10-2019
| | Posted on Monday, April 27, 2020 - 05:39 pm: |
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Great picture Miro! Be nice to see a video of it doing its job but that might be a little hard to do safely. This is quite a handy feature. My friend cut the main piece out of 1/8" stainless in two halves using a CNC plasma cutter table which I'd never even heard of before that. He tried to emulate the shape but he programmed a little bit too little sweep on the skeg and the prop tips hit it, so we trimmed it back some. It still does the function but doesnt stick down as much as the real dispro skeg.
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miro
Senior Member
Username: miro
Post Number: 1078
Registered: 11-2001
| | Posted on Wednesday, April 29, 2020 - 11:11 pm: |
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looks like you are using a prop bigger than 9 in.
That was the limit for the DisPro device. With the 2 cylinder copper jacket engines, they used a 4 blade prop .
Some of the later DisPro models used a 18 in pitch prop ( still 9 in dia) with the Coventry Victor engines. |
bruce
Senior Member
Username: bruce
Post Number: 700
Registered: 07-2002
| | Posted on Thursday, April 30, 2020 - 11:46 am: |
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Good stuff Miro. So what is the usual prop for the Dispro with the 1 cyl Dispro engine?? two blade 9 inch with ??? pitch?? |
ernie
Senior Member
Username: ernie
Post Number: 2589
Registered: 01-2002
| | Posted on Thursday, April 30, 2020 - 03:50 pm: |
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I have found when playing with old engines and needing to slow the engine down with the prop and you can't do it with diameter adding pitch works well. However smaller high pitch props are sometimes hard to find. Outboard props are easy to get and cheap, if not free and usually are small diameter and high pitch. Once you find one that works then use the diameter and pitch to get a real prop for the inboard. On one boat I was fooling around with I even found a tapered ream that was real close to the shaft taper and used it on the outboard prop. |
miro
Senior Member
Username: miro
Post Number: 1080
Registered: 11-2001
| | Posted on Sunday, May 03, 2020 - 09:47 pm: |
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Sorry for the late reply - the pitch on the 2 blade prop is 14 inches.
I suspect that your engine will be more than able to handle that.
Maybe think about a 3 blade prop.
miro |
