cutlass bearing

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Ardenfour

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Daft thing i done!
I've just bought a trintella 29, with aircooled engine. As the boat is on the hard, I decided to start the engine, which seems to run fine, however then i put it in gear, revved it up and climbed down to watch the prop merrily spinning away. Then I noticed bits of rubber appearing around the shaft and the onset of increased vibration. I presume I have knackered the cutlass bearing (duh!) How big a job to fix? And what are the consequences of launching in this state? - I have to be out the compound shortly, and face a 20 mile sea journey with mast down and then through canal system before I can sail her.

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Peter, agree with summary of action, however not to much of a problem 'cos you should be able to obtain replacement cutlass bearing without any difficulties. You need to know your shaft diameter & Length of bearing, and your local swindlery will be only to pleased to help. To remove old one, should be a couple of allen screws on the o/side of the stern gear, undo... you will of course have taken the prop off!, if you can find something solid, pointy, and sharp you should be able to ease the bearing out of the s/gear...one of those occasions when applied brute force comes to mind...If you ran the prop long enough to melt the rubber (and weld it to the shaft) you may have to undo your stern coupling to push the shaft out a few inches, to make a start, a hacksaw is not a bad tool for the job..... Hope this Helps ...Tony W.

<hr width=100% size=1>Tony W.
 
Would not reccommend launching boat until fixed....not too diifficult and a lot easier than fixing the person who might have been leaning on the prop........

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Agree with don't launch.

You need to measure the inside diameter of the bracket and the shaft diameter to get the right replacement.

There are various tricks to getting the cutlass bearing out. Sometimes its easier to remove the shaft to allow you to thread a hacksaw up through the cutlass bearing and cut a slot. Last one I did, I found a peice of aluminium pipe the right diameter and used it as a drift.

I had to hunt for the allen grub screws first - they were hidden under filler and antifouling

You can sometimes manage with the shaft in place. I have heard of people using a split tube and a fabricated puller and removing the bearing sliding it down the shaft.

You will probably need a puller to get the prop off anyway.

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i think that from memory u r will have to remove rudder to get the prop off the shaft.
sometimes the old bearing can be difficult to remove from its housing, proberbly u will need to take the housing from the boat.
if u dont do it prior to launch the shaft will "knock" badly like a "stick in a dustbin"
good luck

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Unless the rudder is going to come off easily, it is worth first trying the split tube method mentioned by John Morris above, though I don't see how you can use it in conjunction with a standard puller. I have used this method successfully by tapping the tube with a lump hammer slid along the shaft.

Mick

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Sorry - wasn't thinking properly regarding the puller. To use the split tube method you need to make up a couple of plates and get yourself some lengths of studding. 12 mm mild steel would do. The plates should be fairly substantial or strengthened with angle iron or similar. you need a 'u' in the one end that will just fit round the shaft (and on which the split tubes then bear) and a hole in the other end just bigger than the outside diameter of the cutlas bearing.

pm me if you want a drawing.

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Re: cutlass bearing - Easy

You MUST fix before launch or the increased play will a) wear out your stern seal and possibly b) knacker your gearbox and or flexible plate between gearbox and flywheel c) cause rings in the shaft so any new cutlass bearing will wear out quickly and d) could stress the shaft to cause failure.

Can be done without removing rudder as long as you have enough clearance to slide a new bearing over the taper onto the shaft once the prop is removed.

Two ways to get out old bearing both need the grub screws removing from side of p bracket. If allen screw keys are loose in the grub screws get the next size key up and grind down to get a very tight fit so you do not have to drill out screws and retap threads.

You can then either carefully cut down through the rubber and outer normally brass shell with a juinor hacksaw, this takes care and a long time but I have done it, then punch the old shell out with small punches again taking great care with the shaft surface or much better way is:
Cut a length of pipe the same length as the p bracket, of pipe internal diamenter same dia as shaft, cut pipe in two, weld a solid knocking knob on it and tap out the old bearing whole. Once the tool has been made up the tapping out takes less than 5 mins.

Once the old bearing has been removed, assess the state of the shaft bearing surface, tap the new bearing in, make dimples in the bearing housing grub screw holes for the grub screws to home in ( this makes removing the bearing next time easier)
and put your prop back on. Make sure yoour prop full goes up the taper and is not binding on the woodruff key which is a common mistake and so called cowboy marine 'engineers' often do not bother with this aspect of fitting.

Having made the tool keep it in your tool box with your prop tools, I caught a rope in the Channel Isles and changed the cutlass bearing over lunchtime, it really is as quick as that even with a Gori 3 blade folding prop.

PS get your bearing from Countrose the makers, they will supply slightly different undersize bearings to take into account shaft weardown. Web site is good and explains all


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I replaced mine last year, biggest problem was removing the old one. It was a composit shell with rubber bearing bonded into p bracket. Tried driving it out with a press to no avail, in the end I useda scredriver to seperate the rubber from the shell then carefully broke up the shell with a chisel before cleaning up and bonding in the new bearing. Spent hours trying to push out the old one, in the end using screwdriver and chisel it took about 45 minutes!!!!!

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I am having difficulty getting my head round this. How do you get the bearing out without removing the shaft? Do you split a tube and drive it through from the inside? in which case what about the shaft seal or gland? Cutting with a junior hacksaw requires access to both sides of the p housing and the shaft removed.

I agree completely that the boat must not be launched without replacing the bearing, also the inboard end seal or packing gland should be checked at the same time.

<hr width=100% size=1>Ken Johnson
 
In my previous comments I was assuming that the cutlass bearing was in a 'P' bracket and you have access to both fore and aft ends of it. If the cutlass bearing is in a sterntube or deadwood, then I don't think that there is a method that doen't involve first removing the shaft. There is usually a bearing housing that has two or more screws in flanges and once you have undone them (!!!) you then usually unscrew the whole assembly out of the deadwood/sterntube assembly.

The very best way to do this is to make a tool out of 10mm steel plate or similar which looks like a ring spanner but instead of the normal ring, you start with a much larger plate and cut and file it into the shape that fits onto the bit of the bearing housing sticking out of the deadwood. (Its often a sort of diamond shape with rounded corners.) I have never come across one that didn't require a large hammer on the purpose built tool to start it. Once its out, you can press/cut/ chisel the old cutlass bearing out and reassemble in reverse order.

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Ken, if the prop's off and allen screws undone, tis possible to lever enough of (with pointy strong bit of something) cutlass bearing out to get a decent grip on it! and if it's worn it will slide down the shaft...... To replace mine on the old boat would have meant taking engine out & probably dropping rudder off, as well..Regards Tony W

<hr width=100% size=1>Tony W.
 
Take the shaft out, its so simple and a good opportunity to replace packing in shaft seal as well, another scary job thta is actually dead easy

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