Prop Clearance between Hull and Strut
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=18642
Printed Date: November-18-2024 at 6:43pm
Topic: Prop Clearance between Hull and Strut
Posted By: luckyenough
Subject: Prop Clearance between Hull and Strut
Date Posted: July-19-2010 at 5:40pm
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PO replaced the 1” dia. prop shaft and the gap between the prop and strut is 5/16 of an inch. The gap between the hull and the top blade of my 13” prop is 1”. I have read on this site that the strut gap should be 1 to 1 ½ X the dia. of the shaft and the hull gap should be 10% of the prop dia. Eric recommended a precision spacer. What are good stock dimensions that I should shoot for? Is one more important than the other? 1989 Sierra Supreme 20’ |
Replies:
Posted By: 8122pbrainard
Date Posted: July-19-2010 at 6:05pm
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The hull to prop clearance is fine at 1". Yes it's under the rule of thumb but you'll be ok.
Go with Eric's idea with the spacer. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: Whitfield
Date Posted: July-19-2010 at 9:15pm
My prop to strut clearance is the same...
Where do we get drive line spacer hardware? ------------- Michael .... I'm the black sheep ~ 1984 Dixie 299 Super Skier (350 Chev PCM / counter rotation / Velvet drive) Open Bow. |
Posted By: 8122pbrainard
Date Posted: July-19-2010 at 9:54pm
Give Eric a call. I have never seen a spacer but it sure wouldn't be a hard part to machine. I know Eric hates what I did and has already come down on me for it but I did have a problem after putting a new bottom on my X55. I made a new shaft for it myself and mustn't have read the tape measure very well. It turned out a inch short. Being lazy, and not wanting to machine up a new one, I installed what's called a "prop saver". It's a urethane disk that bolts between the coupling halves from both couplings. The idea is that if you take a prop hit, it will shear hopefully saving you from trans as well as some prop damage. It's also a "buffer" for vibration. It is NOT a fix for shaft alignment issues!! I'll come back with a link but feel any of the on line marine suppliers have them. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Whitfield wrote:Posted By: 8122pbrainard
Date Posted: July-19-2010 at 10:16pm
I found it after some searching. http://www.getaprop.com/content-product_info/product_id-1424/drivesaver_454.html - driversaver insert It will add about 3/4" to 1" to your prop shaft length. Taking the prop to strut clearance out to where it should be. Eric let me have it!!  I will say again especially since I just did the alignment clinic at GL this last Friday that this id NOT a excuse for not aligning your shaft! Don't believe the "Madison avenue" marketing hype!!------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: Riley
Date Posted: July-19-2010 at 10:49pm
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I just changed a friends prop on a set up like that. You have to seperate the couplings to put the puller on the prop. PIA!
Pete, I can't believe you did that to your Dunphy. ------------- |
Posted By: 8122pbrainard
Date Posted: July-19-2010 at 10:55pm
Bruce, Because it's not original???? Well, it was ether that or machine up a new shaft due to my 1" mistake!!! I'll admit it was a "quick and dirty" fix that I've never gotten around to fixing. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: Riley
Date Posted: July-19-2010 at 10:58pm
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Partly, but mostly because it's Hokey! ------------- |
Posted By: 8122pbrainard
Date Posted: July-19-2010 at 11:08pm
Yup!!! I'll bet Eric will "ream" me again in the morning! It's not my normal "style"!!!------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: Whitfield
Date Posted: July-20-2010 at 1:47am
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Wow at $350 I can buy a new shaft.
I don't think that coupler cushion will have much effect on the flywheel mass of a brass prop turning 2500RPM's. Whipping out my car parts arsenal... This is a pic of the 1" 4wd drive shaft spacer we run (anodized aluminium) ~ $24.95 I've gotta imagine a custom machined 1/2" part can't be much more then $40.  ------------- Michael .... I'm the black sheep ~ 1984 Dixie 299 Super Skier (350 Chev PCM / counter rotation / Velvet drive) Open Bow. |
Posted By: 8122pbrainard
Date Posted: July-20-2010 at 11:24am
The one I found back in roughly 82 when I put the new bottom on the boat sure wasn't very expensive. The link I posted isn't the same brand I used. It was less than $100 but you are correct that I just should have made up a new shaft. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: Riley
Date Posted: July-20-2010 at 11:31am
Pete, I can't believe you admitted to doing that. 
I love being creative with the Rube Goldberg type fix, but I have my limits. ------------- |
Posted By: luckyenough
Date Posted: July-20-2010 at 12:39pm
| Is 1" off the strut a good number? What is stock on most of the boats? |
Posted By: 8122pbrainard
Date Posted: July-20-2010 at 1:05pm
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Tom,
Yes shoot for around 1". I've seen more but you want to be close to the cutlass bearing for radial loading from the prop but still have plenty of room for water flow through it. Bruce, I'm a honest type and do admit openly to making a non original mistake!! It's funny but my "keeping it original" beliefs have gotten stonger through the years. In 82 it crossed my mind but now I wouldn't even consider doing something like that!! The ACBS and it's judging rules have sunk in quite deep!! Also I need to be real careful being judge qualified. BTW, the "drive saver" insert on the X wouldn't be a deduction. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |