Prop Distance
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Boat Maintenance
Forum Discription: Discuss maintenance of your Correct Craft
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=4215
Printed Date: May-23-2024 at 9:57am
Topic: Prop Distance
Posted By: Bman
Subject: Prop Distance
Date Posted: July-18-2006 at 5:57pm
Ok after a bend propshaft due to alignment i think, im wondering how far the prop should
A, be away from the strut
B, be away from the rudder
C, be away from the floor
i ask this because the prop was quite close to the rudder and a long way from the strut and floor but looking at my friends 2001, the prop is close to the strut and floor.
im thinking theres a formula to work out the optimum positioning. but i don't know it.
oh and my lovely craft is a 79' ski nautique
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Replies:
Posted By: Tim D
Date Posted: July-18-2006 at 9:44pm
The drive shaft is tappered and so is the inside of the prop, both mate together to a certain point.
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Tim D
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Posted By: Bman
Date Posted: July-19-2006 at 1:16am
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Yes i know that let me ask the question another way, How long should the prop shaft be on a 79' ski nautique?
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Posted By: 79nautique
Date Posted: July-19-2006 at 9:34am
it should be 50" long 1" diameter shaft from the factory.
make sure it has not pulled out of the coupler. Check where it mounts to the tranny and make sure the the end of the shaft is pretty close to flush with the face of the coupler, you'll have to remove the four bolts and slide it back to see.
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http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique
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Posted By: David F
Date Posted: July-19-2006 at 10:38am
79Nautique:
How far away is the prop hub from the strut with a 50" factory length shaft? I think this is what Bman is asking. And, can that distance be shortened a bit without putting the prop blades too close to the bottom of the hull for comfort. Seems to me that the close the prop hub is the strut the better (to help reduce vibration and fatigue).
I seem to remember others having issues with broken shafts due to the distance between prop and strut...or at least that was the suspected cause.
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Posted By: 79nautique
Date Posted: July-19-2006 at 10:42am
you can shorten it I use a acme 470 with a 49 1/2" long shaft on mine. Talking with Dennis at MWCC he gave me the 50" and it's about an 1" or so from the strut
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http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique
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Posted By: David F
Date Posted: July-19-2006 at 11:11am
I think an 1" from the strut should be fine and maybe give a little more freedom in choosing props. But closer is better for fatique/vibration resistance IMHO.
What prop are you running and what is your prop to hull clearance?
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Posted By: Bman
Date Posted: July-19-2006 at 3:29pm
thats more like the info i need cheers, i am a tad confused still as the that bent was 48" long but i had 3-4 inches between the strut and prop but 1/2 - 3/4 of that could of been distance from the gearbox to shaft as there was a gap.
im beginning to wonder how original the strut is, it was well out of alignment when i took it of ( it was in line with the engine but it rubbed out the top front and bottom rear of the bearing) and it also had 1 good 1/4'' packing in the front bolt holes to reduce that also.
Has anyone got a pic and maybe the angle the strut should be?
Cheers Guys
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Posted By: Bman
Date Posted: July-19-2006 at 3:33pm
OOh not sure of the prop but although i didnt think it was that bad, a friend of a friend who's sorting it said it was well shafted excuse the pun. im thinking its original or at least original spec, was looking at those acme props from skidim there seroiusly cheap compared to a standard one over here. just the postage that may kill the bargain.
Don't suppose anyone has a technical drawing of a suitable prop?
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