Ski Boat Forum
Repairs and Maintenance => Boat Maintenance - American Skier => Topic started by: phil on December 20, 2009, 11:54:28 AM
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My rudder has pretty bad cativation burn on it. I've been contemplating replacing it for a few years now and perhaps this spring I'll do it.. I could probably also use a new prop. My prop is not bad but it's the original nebral (federal i think) 13x13 and there are minor dings in it. How are rudders replaced?
It looks like in order to get the prop/rudder off the boat would need to be off the trailer because the rudder won't drop all the way down without hitting the trailer. Is there any way to get the rudder off without hoisting the boat off the trailer? How should I go about getting the rudder off? Also, when should a prop be replaced? I'm trying to figure out if I really need to replace my prop and if I'll notice any difference as far as how the boat drives. Also, would you recommend something other than a 13x13?
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Phil
I'm not sure that the rudder needs replaced from cavitation burn, never seen one that bad. Are you having a handleing problem? I woul suggest looking at the steering mechanism at helm, the cable, the mount for the cable at the rudder, loose connection at the rudder, or worn packing. The way the cable is mounted on mine, the cast aluminium piece has ball end to pivot and it is wore out, it comes out of socket = no steering. If you have to pull the rudder, the easiest way is to slide the boat back on the trailer to clear the prop guard. Make sure to block the rear of the trailer or leave it hooked to a truck while doing. Replace the packing since you already have it apart.
The prop is more important to be repaired if there is even minor damage. Even minor damage will cause cavitation and more importantly, vibration which leads to more damage. I would suggest removing the prop, using a prop puller to prevent further damage, and having it rebuilt. I'm sure it is the best prop for your boat if it is the original, however a four blade may give you more "traction" for a steadier pull but you may loose some top end speed 1-5 MPH. When you do the prop look to see if the strut bearing has excessive wear, the prop shaft is not bent, and do an engine alignment before running and the boat should handle like new.
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No handling problem, and everything seems smooth. The tranny was rebuilt around 2001.
It looks pretty bad, check it out.
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Phil for your boat I have a couple of favorites, give me a shout when your ready
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Will do Dan. I'm about positive that I want a new prop this spring. I'll get in touch with you when the time comes.
Thanks.
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All good advice above, based on the picture of the rudder I would reccomend replacing it, the casting erosion is getting too close to the rudder post for my comfort zone.
Easy way to do this whit access to a non-frozen lake is to run the boat low on fuel, (reduce weight in tank) load boat onto trailer about 6" short of the bow stop & tie it down there. When the tiller arm is off the rudder can be rotated 90 deg. and slide down to the floor. When doing this alone I put something an inch below the rudder to keep it from falling but allows me to turn it from inside while taking it apart.
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Should I get the rudder from Dan? Looks like I'll be replacing rudder and prop this spring. The rudder I think I can handle replacing but replacing the prop should be interesting as I've never done it before nor do I have a prop puller.
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Just a question, is this rudder damage from cavitation, or is it caused from something else? I have never seen this before, although I have seen damage from cavitation on props this bad. As for the prop removal, if you buy a new prop or get it rebuilt maybe they will loan you one (with a deposit).
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Never mind the first part of my last post, it sure looks like cavitation burn!
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Never mind the first part of my last post, it sure looks like cavitation burn!
I know it's kind of crazy....
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Phil
I belive you are in WI. I am in IL so if you can't get a puller maybe I can loan you mine somehow. I could ship it to you, but to and return shipping might cost as much as just buying one.
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That would be awesome. Obviously, I would cover shipping..
Where at in Ill? I grew up in Southeast Wisconsin just across the border of Ill and go down there often to visit.
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The "cavitation burn" is caused from high pressure aeration from the prop, in other words the prop wash is slamin against the rudder blade were you see the problem. Increase/decrease the distance between the two will affect the rudder burn. If you doubt the power high pressure water can do vist a web site that sell water jet cutting equipment & see what water can cut!
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Ron
Was this common on these boats, I've never seen it before this and I don't notice it on my rudder? Just curious. I've seen props and jet boat impellers of SS that look like that so I know that it happens. Phil, I live about 1 1/2 hours south of the WI border, 20 miles east of I-39. Let me know about the puller when that time comes.
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Brandon, Ron & Phil,
I finally got Brandon's SS prop & new rudder installed. Both came out easily and I didnt need a prop puller - both the old & the new props slid on tightly up the taper without any problem. I noticed after a few hours on the lake that the new rudder is showing slight markings in the same areas as the cavitation burns on the old rudder... If you recall my cavitation burns were as bad as Phils... I dont know how the prop & rudder could be too CLOSE or too FAR apart (see Ron's comments above) and I dont THINK I have excessive vibration... My brother has owned inboard boats for quite some time and he didnt notice any undue vibration either... :)
Do they make shorter / longer prop shafts? Any other ideas on why this would be occurring???
Thanks guys!!
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Joel, How many hours were on your old rudder? Mine has about 800.
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IF the engine meter is correct and IF the prop was original... about 680 hours. It occurred on both sides of the rudder in different locations... top right & bottom left - or there abouts - with the top being the worse. The prop had quite a bit of perosity / small holes, but it was evenly dispursed throughout each blade...
Boggles the mind... I'm waiting for Ron & Dan to chime in since they know these boats better than anyone.
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It's a delicate balance of measurments, getting the engine positioned for the correct CG, then installing the drivetrain with service area while trying to maintain minimal shaft angle. Distance between the prop hub & strutt should be kept a a minimum with just enough room for a puller to get in there. Usually about 3/4" Next is the prop itself the older boats were designed around the Michigan Wheel props that had short raked blades, the newer props increased the rake like an OJ which creates more cavitaion on the rudder.
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I'm thinking both props are probably a newer style rudder... Damn OJ strikes again!!! :( Sounds like another "Winter Project" to determine what to do... if I need to do anything ;)