Cutlass bearing/stern gland

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Ursula123

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Hi,
I'm just in the process of having to lift the engine to draw the shaft to replace my cutlass in my recently acquired and re-engined Ohlson 35, it seems not much thought was put into the installation in 2004, the traditional sterngland is practically inaccessible with the engine in situ, which is a tad worrying.
So two matters I need advice on, I need a maintenance free shaft seal to replace my traditional stuffing box and are all cutlass bearing the same or do some last longer as I don't want to have to do this again in a hurry!
Any manufacturers recommendations or suppliers and any experiences would be very helpful. Thanks
 
use vesconite (google search)in your cutlass bearing and either a PSS shaft seal (lake-engineering) or MTM900 (ASAP supplies)
should sort your worries out
 
That sounds like very serious work on two accounts:

1 cutless bearing and stern gland replacement
2 ongoing maintenance and access to the shaft seal.

Removing the engine is a drastic solution, and I wonder if it might be possible to install a good strong waterproof access hatch in the cockpit sole, so that you can do the necessary work for the replacements, and from time to time thereafter gain access to the shaft seal for peace of mind maintenance. FWIW I had a hatch nearly 2ft square in the cockpit on a previous saily boat; it revolutionised access and general checking /oil filter work.
 
PSS is a good choice but it does need some attention prior to launch to ensure the faces are wet. Somewhat similar to burping but only needs doing once per year. You do need access to the seal to do it. You might need to fit another type that is safe without attention.
 
The engine removal is to draw the shaft to replace the cutlass, sadly there is no other way around it, it fouls both the P bracket and rudder skeg so can't draw it out so it has to come inside. the engine needs sliding forward and lifting to get the shaft under it. Think I might develop a P bracket that screws together in two halves like a shaft anode, I can't believe the work involved just to replace a cutlass. The previous owner also glued and screwed the box/step which I have had to damage to dismantle.
I have thought about a sole hatch in the cockpit but am concerned that I would have top cut through at least one of the GRP stringers and worry about the loss of rigidity. Thanks for your input.
 
Are you sure you can't drive the cutless bearing out with the shaft in situ? I helped a mate do this on his Etap. The bearing was a tight push fit in the bracket and located by a grub screw. I thought this was a pretty much standard arrangement.

The bearing itself had to be machined to fit, but as this is the case with my boat as well, i guess it's pretty much de-rigour.

Actually it may be necessary to withdraw the shaft to do the seal anyway, but you have the opportunity to examine the P bracket and determine if it is possible to remove the cutless bearing with the shaft in situ for future replacements.
 
Last edited:
Ursula123 said:
The engine removal is to draw the shaft to replace the cutlass, sadly there is no other way around it, it fouls both the P bracket and rudder skeg so can't draw it out so it has to come inside. the engine needs sliding forward and lifting to get the shaft under it. Think I might develop a P bracket that screws together in two halves like a shaft anode, I can't believe the work involved just to replace a cutlass. The previous owner also glued and screwed the box/step which I have had to damage to dismantle.
I have thought about a sole hatch in the cockpit but am concerned that I would have top cut through at least one of the GRP stringers and worry about the loss of rigidity. Thanks for your input.
Click to expand...

If you have a P-Bracket, it is possible to remove the cutless without withdrawing the shaft. I made a 'tool' to do this.

1. Find a piece of thick-walled metal tube (I used an aluminium) that is roughly the same external dia. as the internal dia. of the P-bracket. Cut it in half longitudinally. This will be your 'pile driver'
2. Find two thick (10mm at least) pieces of steel, about 5" x 3".
3. Cut a hole in the centre of one, slightly larger than the I/D of the P-bracket. The other slightly lager than the propshaft dia.
4. Using a hacksaw, turn the smaller hole in one of them into a U, so it can slot over the inboard end of the propshaft.
5. Get two lengths of studding rod with big square washers & nuts from DIY/Builders merchant
6. Drill holes in both the bits of steel either side of the 'big hole' & the 'U' This will be your 'compressor'.
7. Clamp the two pieces of the 'pilerdriver' together with hose clips around the shaft (NB, not gripping it), inboard of the P-bracket .
8. 'U' metal inboard, 'hole' metal outboard, bolt up & wind away.

I've used mine twice & lent it to other local forumites, all successfully.

Hope this helps.
 
As a supplier of water lubricated shaft bearings I could be biased, but in tests carried out by a working Pilot boat and wear rate measured by a surveyor Maritex Aquarius composite bearings lasted about three times as long as a good quality rubber bearings. The other plastic materials are quite good but suffer from creep as friction causes heat and they soften or deform. The composites benefit from having lubricants in the matrix that help when the shaft runs dry as it will during start up and run down. Having said that they are significantly more expensive and it is difficult to predict actual wear rates as there are too many variables that can have an effect.

Be aware that all materials have some moisture absorption but a larger factor is usually the thermal expansion, both of these have to be allowed for as well as bearing wall thickness when working out the running clearance.

In terms of fitting we advise a clearance fit that you can slide in by hand and then bed on epoxy after a trial dry run.

Maritex Aquarius is Lloyds approved and in wear rate tests for rudder bearings showed no wear of shaft or bearing after 1000 hours at increasing loads
 
You will have to move the engine to replace the seal anyway. What you replace it with will depend on two things. First the end of your stern tube and second the amount of space between the stern tube and the coupling. Most of the face seals such as PSS and housed lip seals Like tides Marine are quite long. The shortest seal is the Volvo/Radice rubber type at 110mm.

No seals are totally maintenance free. All require at least once a year to either grease or check the faces and compression of the bellows. Arguably the easiest is the Radice as it has a grease point on the top and a positive vent to eliminate air - or it can have a positive water feed from the engine. However it is available in a limited range of sizes. Shaft size should be OK but you need to measure stern tube outer diameter carefully.
 
Even if you take the shaft out to do the cutless bearing you will still need some form of mandrel so may as well do it in situ as it's about the same work, you may be able to with draw the shaft with the prop off enough to change the gland or seal, mine does just enough before it hits the skeg
 
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