vibration during turns
Printed From: CorrectCraftFan.com
Category: General Correct Craft Discussion
Forum Name: General Discussion
Forum Discription: Anything Correct Craft
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=145
Printed Date: December-02-2024 at 5:54pm
Topic: vibration during turns
Posted By: nauti girl
Subject: vibration during turns
Date Posted: February-15-2004 at 5:45pm
I'm new to the inboard ski boats. We bought a '78 Martinique 351W Commander toward the end of last summer. I notice when my skier falls and I turn around at speed I feel a lot of vibration. Is this normal? Does it mean I need a shaft bushing? ...or a rudder bushing? ...or should I just get used to it?
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Nauti Girl
--I think my husband uses his own login now!
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Replies:
Posted By: tryan
Date Posted: February-15-2004 at 11:28pm
i would check those, but could be numerous things.
first, i would check the bolts into the stringers for the motor/tranny mounts and your alignment.
second, i would look at the driveline to see if everything is 'true.'
see if the end block on the steering cable is tight onto the stringer also.
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http://www.correctcraftfan.com/diaries/details.asp?ID=146&yrstart=1971&yrend=1975 - promo http://www.correctcraftfan.com/diaries/details.asp?ID=192&yrstart=1925&yrend=1970 - #2
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Posted By: Jeff
Date Posted: February-16-2004 at 6:06pm
Nauti Girl,
You may be experiencing propeller cavitation. Are you turning around the same direction each time? Try turning the other direction and see if the vibration changes. My '89 Nautique sensitive to direction in a sharp turn.
Jeff
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Posted By: nauti girl
Date Posted: February-16-2004 at 9:13pm
Jeff,
Now that you mention it, I do always turn left. My boat is winterized now, so it'll be another couple of months before I can try your idea. Has your '89 always had this vibration? ...or is there something we could do about it? I never experienced this with outboards (not that I would EVER go back). I love the way these boats almost "slide" around a curve like a car rather that "bank up" like an outboard.
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Nauti Girl
--I think my husband uses his own login now!
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Posted By: SS-201
Date Posted: February-16-2004 at 9:27pm
One reason for vibration in that particular situation is that the prop sits back to far from the strut and causes vibratio ,among others. Your condition could be other reasons, not knowing your boat condition. However the prop only needs to be the width of a propeller puller 1/4 inch from the back of the strut. However in 1997 they changed amd put the props about 5/8 inch from the strut. A comprise fron a 1/4 inch. This I know because it my suggestion.
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SS 201
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Posted By: Jeff
Date Posted: February-16-2004 at 10:25pm
Nauti,
Mine has had it from day one. I never thought anything of it because the inboard/outboards we had growing up were always susceptible to cavitation. It's also a function of prop rotation direction. My brothers Malibu cavitates turning the other direction, due to his direct drive.
I'd never heard of the prop position problem.
Jeff
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Posted By: SS-201
Date Posted: February-17-2004 at 7:53am
When they changed the prop position the vibrations went away, 1997 for CC. Your experience is because your boat turns the opposite rotation to CC. CC is the only boat in the industry today that turn right hand propellers all the rest are left hand.If you look at all the older boats prior 1997 you will see that the props are 2-4 inches away from the strut.Most all the boat Ski tow boats except maybe Sanger, MB Mike Brendella boats didn't experience this because they both were high performance builders and drivers. I know this because I drove with and against them. The farther the prop away from the rudder the less force against it and makes it easier to steer, also helps to put bow up. IO are completely different situation.
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SS 201
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Posted By: nauti girl
Date Posted: February-17-2004 at 12:51pm
I wonder if I just give it too much abuse. Maybe I need to slow down a little. Don't you think the cavitation will damage it?
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Nauti Girl
--I think my husband uses his own login now!
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Posted By: Jeff
Date Posted: February-17-2004 at 1:24pm
SS-201,
Thanks for the info. When you talk about the distance from the strut to the prop, is that as measured from the trailing edge of the strut body to the forward most portion of the propellor blade, or is it from the strut bushing to the prop hub?
Also, my boat is a 1989 Ski Nautique. I think you had the impression is was not a Correct Craft.
Jeff
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Posted By: SS-201
Date Posted: February-17-2004 at 4:09pm
From the rear of the strut to the front of the prop at least 1/4 inch, so you can use a prop puller. Measure what distance you have now subtract what clearance you are going to choose. You unfortunately will have to cut the front of the shaft where it goes into the coupler, if you choose to do this, as you will be shorting the shaft.
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SS 201
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Posted By: 64 Skier
Date Posted: February-20-2004 at 12:17pm
Dollars to donuts what your experiencing is cavitation. When you turn at skiing RPM's (or higher....great feeling) the forward speed is reduced but the prop is still spinning at high RPM's and pulling water through it which increases cavitation AND the prop is also "sliding" sideways due to the turn which also increases the risk of cavitating the prop.
The prop is also "sideloaded" slightly from the turn and can induce flex into the boat and any misalignment is magnified (make sure you do Tryans post for things to check) it could be both cavitation and misalignments.
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64 Skier
66" HO VTX and 67" HO Triumph
http://www.correctcraftfan.com/diaries/details.asp?ID=1071&sort=&pagenum=3&yrstart=1971&yrend=1975 - 71CC
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Posted By: tryan
Date Posted: February-20-2004 at 9:45pm
one little ping on the leading edge will eat right through an aluminum prop. take a very close look.
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http://www.correctcraftfan.com/diaries/details.asp?ID=146&yrstart=1971&yrend=1975 - promo http://www.correctcraftfan.com/diaries/details.asp?ID=192&yrstart=1925&yrend=1970 - #2
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Posted By: Barracuda
Date Posted: May-12-2004 at 12:44am
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Nauti girl- when my cuda had the wrong sized prop (bought it like this) it would make a ton of noise when turning sharp.This was magnigied when pulling a tube-er.With the correct size and pitch prop, the noise and virbration is drastically reduced.Make sure your prop is sized and pitched correctly for your model.
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Posted By: SS 201
Date Posted: May-12-2004 at 8:13am
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All CC props are now 5/8 of a inch from the strut, as of 1997.
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Posted By: Rick
Date Posted: May-12-2004 at 10:09pm
My 66 came with a 14X11 I had an amazing amount of vibration/Cavitation. I replaced it with a 13X13 and 90% of the vibration went away. I now find that a 12.5X 13 was original Equip.
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http://www.correctcraftfan.com/diaries/details.asp?ID=250&yrstart=1996&yrend=2000%20" rel="nofollow - 2000 Ski
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Posted By: ricktrav
Date Posted: July-16-2004 at 4:05pm
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i never power turn to get a skier even if the water is horrible i still stop then turn and idle to get the skier. why mess up th water to save 5 seconds? I HATE POWER TURNS.
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