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Clearance between prop and rudder

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Peter McBratney
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Clearance between prop and rudder

Post by Peter McBratney » Sat Feb 17, 2024 1:58 am

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

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Jim Godlewski
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Re: Clearance between prop and rudder

Post by Jim Godlewski » Fri Feb 23, 2024 10:39 am

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

Peter McBratney
Posts: 46
Joined: Wed Jun 13, 2007 3:04 am
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Re: Clearance between prop and rudder

Post by Peter McBratney » Sun Mar 03, 2024 1:46 am

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

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Jim Godlewski
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Re: Clearance between prop and rudder

Post by Jim Godlewski » Sun Mar 03, 2024 8:19 am

1956 17 Sportsman CC-17-2310
1930 Model 100 7152

Peter McBratney
Posts: 46
Joined: Wed Jun 13, 2007 3:04 am
Contact:

Re: Clearance between prop and rudder

Post by Peter McBratney » Thu Mar 07, 2024 2:34 am

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

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Jim Godlewski
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Re: Clearance between prop and rudder

Post by Jim Godlewski » Thu Mar 07, 2024 7:44 am

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

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