31-foot Dorians,
After talking with my mechanic and checking a number of other possible causes, it seems likely that the minor overheating problems that I've been having (we have to stick to 2000 rpm to keep temp below 190) are due to an over-pitched, three-bladed prop. Because the markings on the prop have been obliterated, I'll have to haul the boat and have the prop measured before proceeding. To help, I'd appreciate answers to two questions:
(1) what diameter and pitch have folks been using for 3-bladed wheels with the Universal 25 on CD31's?
(2) with such a prop, what speed do you attain at 2000 rpm in calm water?
Thanks!
David Brownlee
CD31 #1 Windrush
Havre de Grace, MD
dbrownle@sas.upenn.edu
CD31 3-bladed prop
Moderator: Jim Walsh
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len
Re: CD31 3-bladed prop
dave
i don't know pitch etc. details - in calm water my 3 bladed prop pushes the boat at about 5 kn
len
md.frel@nwh.org
i don't know pitch etc. details - in calm water my 3 bladed prop pushes the boat at about 5 kn
len
md.frel@nwh.org
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Michael Soloway
Re: CD31 3-bladed prop
Dear David,
I think I answered this once, but when I bought my CD31 this spring it had a 3 bladed prop on it. John Doyle surveyed it for me, and he first noticed it when we examined the boat out of the water. He may know the technical details. Also included in the deal was another 3 bladed prop asnd the original 2 bladed one. When I asked the owner about the big prop he said that he "liked to have brakes". I try not to rev much over 2000 and I have never overheated. I can cruise comfortably and routinely at 6.2 or 6.3 kts. Reverse is impossible and completely unpredictable and I attribute that to the prop, although I have no real logic behind that statement. I don't yet understand pitch and all of that yet so that is all that I can tell you. So far I have no complaints about the boat's ability to motor forward in the currents of the Hudson River and NY Harbor.
Michael Soloway
CD31 "Puffin" #60
m@msoloway.com
I think I answered this once, but when I bought my CD31 this spring it had a 3 bladed prop on it. John Doyle surveyed it for me, and he first noticed it when we examined the boat out of the water. He may know the technical details. Also included in the deal was another 3 bladed prop asnd the original 2 bladed one. When I asked the owner about the big prop he said that he "liked to have brakes". I try not to rev much over 2000 and I have never overheated. I can cruise comfortably and routinely at 6.2 or 6.3 kts. Reverse is impossible and completely unpredictable and I attribute that to the prop, although I have no real logic behind that statement. I don't yet understand pitch and all of that yet so that is all that I can tell you. So far I have no complaints about the boat's ability to motor forward in the currents of the Hudson River and NY Harbor.
Michael Soloway
CD31 "Puffin" #60
m@msoloway.com
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Ken Cave
Re: It ain't the prop!!
It ain't the prop that is giving you fits-it is the full keel boat!
I bet if you survey every Cape Dory owner in backing up-you will find that you have a lot of company on this issue. The Cape Dory will turn on a dime going foward-but reverse-it has a mind of its own!!
Ken Cave
bcave@whidbey.net
I bet if you survey every Cape Dory owner in backing up-you will find that you have a lot of company on this issue. The Cape Dory will turn on a dime going foward-but reverse-it has a mind of its own!!
Ken Cave
bcave@whidbey.net