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Clearance between prop and rudder
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Clearance between prop and rudder
After a great many years I have finally got my 19ft Capri into the water! Great feeling and a life's work, so my wife says.
I needed to totally rebuild the boat, taking the plans from the museum and needing to re-establish the hull and all the fundamental dimensions. I think I have ended up with the prop too close to the rudder. It is about 7/8 clearance at the top and larger at the bottom due to the inclination of the prop shaft. I noticed a little vibration coming through the steering at low to medium revs and wondered if that is the clearance.
Can anyone give a guide as to what is the recommended clearance? I can shorten the shaft to achieve increased clearance. Thanks
I needed to totally rebuild the boat, taking the plans from the museum and needing to re-establish the hull and all the fundamental dimensions. I think I have ended up with the prop too close to the rudder. It is about 7/8 clearance at the top and larger at the bottom due to the inclination of the prop shaft. I noticed a little vibration coming through the steering at low to medium revs and wondered if that is the clearance.
Can anyone give a guide as to what is the recommended clearance? I can shorten the shaft to achieve increased clearance. Thanks
- Jim Godlewski
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- Location: Saint Clair Shores, Michigan
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Re: Clearance between prop and rudder
What is the measurement from the propeller to the rear of the strut? I'm understanding it should be around 3/4 of an inch.
1956 17 Sportsman CC-17-2310
1930 Model 100 7152
1930 Model 100 7152
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- Posts: 47
- Joined: Wed Jun 13, 2007 3:04 am
- Contact:
Re: Clearance between prop and rudder
Jim, thanks for the reply. Sorry for not checking earlier.
Distance is 2 5/16 inch between prop and strut.
If 3/4 is the go, then my feeling that mine is not right is confirmed.
I don't see an issue with shortening the shaft, once I get it out of the boat. I really don't want to take the engine out, but I think I am going to have trouble pulling the coupling off the shanft. It is not a tapered coupling and looks to be a push fit with keyway and two locking screws. I guess the plus is it has not had time to corode. any ideas?
Regards
Peter
Distance is 2 5/16 inch between prop and strut.
If 3/4 is the go, then my feeling that mine is not right is confirmed.
I don't see an issue with shortening the shaft, once I get it out of the boat. I really don't want to take the engine out, but I think I am going to have trouble pulling the coupling off the shanft. It is not a tapered coupling and looks to be a push fit with keyway and two locking screws. I guess the plus is it has not had time to corode. any ideas?
Regards
Peter
- Jim Godlewski
- Posts: 575
- Joined: Sun Feb 14, 2010 12:32 pm
- Location: Saint Clair Shores, Michigan
- Contact:
Re: Clearance between prop and rudder
1956 17 Sportsman CC-17-2310
1930 Model 100 7152
1930 Model 100 7152
-
- Posts: 47
- Joined: Wed Jun 13, 2007 3:04 am
- Contact:
Re: Clearance between prop and rudder
Thank you Jim
I made up a nice puller that bolts to the propshaft coupling and has a centre bolt to pull the coupling off the shaft. Work of art! Crawled into the boat and fitted it. All good. Then I found I could slide the coupling off the shaft by hand! C'est la vie. Going to shorten the shaft by 40mm.
Thanks for the suggestions via the previous posts.
Regards
Peter
I made up a nice puller that bolts to the propshaft coupling and has a centre bolt to pull the coupling off the shaft. Work of art! Crawled into the boat and fitted it. All good. Then I found I could slide the coupling off the shaft by hand! C'est la vie. Going to shorten the shaft by 40mm.
Thanks for the suggestions via the previous posts.
Regards
Peter
- Jim Godlewski
- Posts: 575
- Joined: Sun Feb 14, 2010 12:32 pm
- Location: Saint Clair Shores, Michigan
- Contact:
Re: Clearance between prop and rudder
Good job on the puller! You may want to replace that loose coupler with a new one. I had the same situation. When I showed my coupler to the place where I got my new SS shaft they said no good. The coupler needs to press fit on. That may be contributing to some of the vibration. Just a suggestion.
1956 17 Sportsman CC-17-2310
1930 Model 100 7152
1930 Model 100 7152
-
- Posts: 47
- Joined: Wed Jun 13, 2007 3:04 am
- Contact:
Re: Clearance between prop and rudder
Hello Jim
I thought you would like to know the outcome.
When I got the shaft to the machinist to shorten and cut the keyway they found the shaft was bent. Not much but discernable visual runout when checked in a lathe. Solution new straight shaft and the coupling is a nice tap on fit. I also took the opportunity to realign the motor / shaft and fit a new shaft seal to the bronze bush and flexible mount to the through hull fitting.
Now all aligned and turns freely, so hoping that the slight vibration will be gone. Either way, I have the satisfaction of knowing it is pretty right now.
Thanks again for your assistance.
The photo is from first launch day.
I thought you would like to know the outcome.
When I got the shaft to the machinist to shorten and cut the keyway they found the shaft was bent. Not much but discernable visual runout when checked in a lathe. Solution new straight shaft and the coupling is a nice tap on fit. I also took the opportunity to realign the motor / shaft and fit a new shaft seal to the bronze bush and flexible mount to the through hull fitting.
Now all aligned and turns freely, so hoping that the slight vibration will be gone. Either way, I have the satisfaction of knowing it is pretty right now.
Thanks again for your assistance.
The photo is from first launch day.
- Jim Godlewski
- Posts: 575
- Joined: Sun Feb 14, 2010 12:32 pm
- Location: Saint Clair Shores, Michigan
- Contact:
Re: Clearance between prop and rudder
Excellent! Keep us posted on your results. The cutless bearing and propeller are two others that will cause vibration if not in good working order.
1956 17 Sportsman CC-17-2310
1930 Model 100 7152
1930 Model 100 7152
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