Pulling and replacing a cutlass bearing in a stern tube

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ILikeRust
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Pulling and replacing a cutlass bearing in a stern tube

Post by ILikeRust »

So how hard is it really to pull out and replace a cutlass bearing in a stern tube?

I'm starting to feel a bit taken advantage of by the boatyard where my boat is on the hard. I keep talking to the guy about things I'm thinking of doing, and asking him how much he would charge to do it, and I did not get a rosy feeling when we talked about having his guys do the cutlass bearing job. At a certain point, I can't do everything, simply because of time and so many projects to do, but by the same token, it looks to me ilke it's not rocket science, and I should be able to do it without too much to-do.

Note that in my boat, it's in a stern tube, not in a prop strut - there is no prop strut in my boat.

My understanding is that you take a reciprocating saw with a long metal-cutting blade and slice the bearing lengthwise (being careful not to damage the stern tube), then collapse it into itself and yank it out. To put the new one in, you chill it on ice for several hours to shrink it a bit, then wipe a little grease on it and use a block of wood to protect it and drive it in with a mallet. Seems pretty easy to me.

The bearing itself is about $75. The boatyard guy is telling me a few hundred bucks to do the job, based on something like a half day's labor, which sounds like way too much to me. Seems to me an experienced boat mechanic should be able to do it in under an hour.

Then of course, the next question will be how bad does the prop shaft look, in terms of wear - I'm going to yank it out and have a look.... a new shaft will be a few hundred as well.
Bill T.
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Tim
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Re: Pulling and replacing a cutlass bearing in a stern tube

Post by Tim »

Sometimes they come right out, in which case it hardly takes more than a few minutes to replace it. They should come right out, but usually they do not because of improper installation in the past.

Sometimes some helpful person in the past epoxied the thing in place, which makes removal substantially more difficult. Fiberglass stern tubes frequently become sloppy over the years, forcing this helpful person to feel they needed to epoxy the bearing in place lest it fall out.

Sometimes it's gobbed in place with gallons of polyurethane adhesive, making removal difficult.

Frequently the oft-read trick of the saw blade doesn't work at all, forcing one to come up with alternate means of trying to pry a 4" long tight-fitting bearing out of a 1-1/2" hole.

When the bearing is inserted flush with the end of the tube, it can make removal more difficult.

Sometimes the heads of the set screws, if installed, are all gunked up or spun out, and the set screws (if installed) have to be drilled out. (You may not have set screws depending on your stern tube/deadwood design; if there's no protruding part of the stern tube outside the deadwood, you won't have set screws.)

I had to laboriously drill one out with a hole saw once. It took a long time. This bearing was mounted flush with the end of the deadwood and epoxied in place. Nothing else I tried worked. Extra time and a new (but sacrificial) 1-3/8" hole saw finally did the trick. Good times.

The point is that it's far too dependent on the individual boat and situation to make any real guesses, but what should be a very straightforward job in theory is in practice frequently a real pain and can easily take a few hours for a 15-minute job. Welcome to boats.

Yours might be a quickie, or might not. Hopefully it is, whether you do it yourself or hire it out. If it is easy, don't blame the boatyard for considering normal-case scenarios beforehand, unless they charge you hours for minutes' work.
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Re: Pulling and replacing a cutlass bearing in a stern tube

Post by Vark »

I say go for it, it's something you should learn how to do. Remove the all the set screws, then try banging it out from inside the boat using a dowel or pipe larger than the prop shaft, go slow and easy. You can try cutting it to release some pressure before tapping it out. Cut slowly in 2-3 places, there is no need to cut it completely through at first. If you find it's glued in try tapping both ends to break the bond, proceed slowly , evaluate each step. Doing the job yourself will build confidence and save money which you can spend on something which absolutely has to be done by the yard, also, you may need a new shaft which costs a few bucks.
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Re: Pulling and replacing a cutlass bearing in a stern tube

Post by Rachel »

I would have written something similar to what Tim wrote, if he hadn't already written it (and probably better than I would have :)

Unfortunately, there are many reasons why it can take much longer than the best-case scenario, and the yard would be remiss to quote you the lowest possible price when they know it could easily take longer.

Also, even if the job does go as fast as possible, it's hard to do *anything* in a half hour as a boatyard worker. By the time you read about the job, gather your tools and parts (after figuring out which size bearing it is and finding or ordering it), and walk out to the boat it's been 15 minutes. You still have to do the job, clean up, put away your tools, and write down a description of what you did. And I'm not talking about lazy slow people; even efficient, sharp, conscientious boatyard workers find the same thing. When you are working on your own boat you can kind of "ignore" those twenty minutes here and there that you spend doing everything but the actual act of pulling out the bearing; but a yard is a business and they have to account for their time somehow.

This is not to say all yards are perfect; of course there are many that are unscrupulous and/or charge for more time than they should. But I don't think that -- on the face of it -- your quote was unreasonable.

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Re: Pulling and replacing a cutlass bearing in a stern tube

Post by Tim »

All this being said, your yard may be run by shysters who are looking to bilk every customer. So please take my comments only in the spirit in which they were intended, not as any means of defense of indefensible business practice. I don't know your yard.
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Re: Pulling and replacing a cutlass bearing in a stern tube

Post by The Froon »

You might consider doing half of the job. Why not attempt, in a very concientious and methodical manner, removing the old bearing and prepping the stern tube for installation of the new bearing by the boat yard? Then again, you are half-way to completion, so you might as well finish the job :)

My approach would be to complete as much as I could (confidently) and then hang there while the boatyard employee finished what I was not willing to 'risk' finishing. The idea being - do what I can do, and then learn the remainder from someone more experienced.

Good luck...It'll be a project I will soon tackle.

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Re: Pulling and replacing a cutlass bearing in a stern tube

Post by Quetzalsailor »

I've done the saw-it-out method on the Morgan. A great deal of work! I did not like the idea of bashing the new cutless in while mounted on fiberglass, so I did the work at home by taking the strut off.

I tried the tap-it-out method on my stern tube in the LeComte. Failed. I tried pressing it out with a concoction of threaded rod, washers, nuts, etc. Failed. I ended up taking the casting out and having the cutless pressed out and a new one installed.
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Re: Pulling and replacing a cutlass bearing in a stern tube

Post by Vark »

You can try removing it as suggested, if it come out easily you're ahead of the game, if things get difficult you can either go with the yard worker or ask for more advice here. If you manage to get it out and a new one in you may have to epoxy the old set screw holes using a hard "filler" then drill and tap new threads. It may be helpful to drill slightly into the bearing outer case to create a dimple which the set screws lock into to help prevent the bearing from breaking loose and spinning.

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ILikeRust
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Re: Pulling and replacing a cutlass bearing in a stern tube

Post by ILikeRust »

I just want to restate for clarity that I do not have a strut supporting the shaft after it exits the the hull. I have a stern tube integral to the hull, with the prop just outside the hull.

Specifically:

Image

Sorry for the lousy picture quality; I cropped it from a larger photo.

I plan on heading up to the boatyard this weekend. I'll take a good look at the situation and take some better photos and see what's what.

Thanks.
Bill T.
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"All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find that it was vanity: but the dreamers of the day are dangerous men, for they may act their dreams with open eyes, to make it possible." - T E Lawrence
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Re: Pulling and replacing a cutlass bearing in a stern tube

Post by Maine Sail »

I really hate to even mention this method but if you're VERY good with a Sawzall and a fine tooth metal cutting blade you can chisel away the rubber along the bottom of the bearing, so you can see metal, then use the Sawzall carefully & slowly with the rudder turned out of the way to cut 98% of the way through the bearing then use a cold chisel to break a corner free and then roll it in on itself.. Please only use this method if you are careful & competent with the sawzall.
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ILikeRust
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Re: Pulling and replacing a cutlass bearing in a stern tube

Post by ILikeRust »

That's the method that was described to me.
Bill T.
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"All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find that it was vanity: but the dreamers of the day are dangerous men, for they may act their dreams with open eyes, to make it possible." - T E Lawrence
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Re: Pulling and replacing a cutlass bearing in a stern tube

Post by Quetzalsailor »

It works fine, but better if you can be sure you're not cutting into the stern tube. And that's hard to do when you can't see what other end of the blade is doing. Quetzal's cutless is about 4" long and fits a 1" shaft, mounted in the trailing edge of the keel, just like yours. Additionally, the stern tube is about 6" long, so there's additional opportunity for damage with a mis-aimed Sawzall.
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Re: Pulling and replacing a cutlass bearing in a stern tube

Post by sscoll »

I did the Sawzall method once. Cutlass bearings are pretty soft. You can finish the cut by hand once you're most of the way through. In my case I decided to really scrutinize the area around the bearing after making most of the cut and found another set screw buried in old paint. The bearing came out by hand after I got that one out.

My question to the group, and I've missed mention of it somewhere earlier, what mixture should I use to put in a plug that I can drill and tap so my set screws have more durable holding when I do the reassembly?

Thanks,
Steve
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Rachel
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Re: Pulling and replacing a cutlass bearing in a stern tube

Post by Rachel »

Another note: If you have the room, it's nice to install the new cutless bearing so that it protrudes slightly from the stern bearing (i.e.aft, into the prop aperture). This way you have something you can grab and tug on (with a tool) when it's time to replace it again.

Something like this (or maybe even a bit more if you could):
cutless.jpg
Last edited by Rachel on Mon Feb 14, 2011 12:24 pm, edited 1 time in total.
Vark
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Re: Pulling and replacing a cutlass bearing in a stern tube

Post by Vark »

Steve,
I'd say for best results use Marine-Tex or West System epoxy or other epoxy mixed with West System "High-density filler", I'm sure there are other products too. You can probably get away with epoxy mixed with colloidal silica or Cabosil .
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