I'am currently considering getting a different prop. for my cd30 with the md7a volvo. am looking at the autoprop located in R.I. so far the size is under question. the info. if any of you have it I need is the aperture clearance for the cd 30 (1982) I didn't think to measure it when boat was hauled last year. this I need to correctly size the new prop. also has anyone used this prop? people I have talked to are very positive about the changes with motor sailing, less drag, more speed, fuel savings etc. I have never been able to run more than 2000 to 2100 rpms @4 knots full throttle with the prop now installed. bucking headwinds and strong currents is exciting but can make bar crossing a very long, tedious and wearing thing. thanks Ben
btlandscapers@imagina.com
aperture
Moderator: Jim Walsh
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Larry DeMers
Re: aperture
Ben,
I also have a CD30 (1983), and have considered the Maxprop. However..I suspect it will not fit without enlargening the aperature or violating the clearance requirements for props. The smallest Maxprop diameter is 14 in. and our props are 13 in. props. All props must have a clearance at the blade tip for anticavitation reasons. This clearance is a fraction of the total diameter of the prop. From memory, my 13in. prop clears the top of the aperture by maybe 1 1/2 - 2 in. max.
Now, it would be interesting to contact Maxprop and the others to see what tip clearances they require for their prop to work well. It is possible that given the different designs of these props, that a 1/2 in. increase in diameter (13in. currently, going to a 14in. prop, with 1/2 of the increase applied to each side of the prop) would not sacrifice the clearance requirements too badly.
To answer your question, I would *guess* that the clearance is at 7 1/2 in. from the shaft exit line center point. I have never measured it though.
If you check witht he Maxprop folks, pass the word back to us please.
Cheers!
Larry DeMers
s/v DeLaMer
Cape Dory 30 ~~~Sailing Lake Superior waters~~~
demers@sgi.com
I also have a CD30 (1983), and have considered the Maxprop. However..I suspect it will not fit without enlargening the aperature or violating the clearance requirements for props. The smallest Maxprop diameter is 14 in. and our props are 13 in. props. All props must have a clearance at the blade tip for anticavitation reasons. This clearance is a fraction of the total diameter of the prop. From memory, my 13in. prop clears the top of the aperture by maybe 1 1/2 - 2 in. max.
Now, it would be interesting to contact Maxprop and the others to see what tip clearances they require for their prop to work well. It is possible that given the different designs of these props, that a 1/2 in. increase in diameter (13in. currently, going to a 14in. prop, with 1/2 of the increase applied to each side of the prop) would not sacrifice the clearance requirements too badly.
To answer your question, I would *guess* that the clearance is at 7 1/2 in. from the shaft exit line center point. I have never measured it though.
If you check witht he Maxprop folks, pass the word back to us please.
Cheers!
Larry DeMers
s/v DeLaMer
Cape Dory 30 ~~~Sailing Lake Superior waters~~~
Ben Thomas wrote: I'am currently considering getting a different prop. for my cd30 with the md7a volvo. am looking at the autoprop located in R.I. so far the size is under question. the info. if any of you have it I need is the aperture clearance for the cd 30 (1982) I didn't think to measure it when boat was hauled last year. this I need to correctly size the new prop. also has anyone used this prop? people I have talked to are very positive about the changes with motor sailing, less drag, more speed, fuel savings etc. I have never been able to run more than 2000 to 2100 rpms @4 knots full throttle with the prop now installed. bucking headwinds and strong currents is exciting but can make bar crossing a very long, tedious and wearing thing. thanks Ben
demers@sgi.com