I have to replace my cutlass bearing this year. There is a first time for everything.

The two pictures below show the inboard and outboard ends of the stern tube.

Has anyone replaced a cutlass bearing on a similar configuration, and if so (apart from the two grub screws in the boss at the business end, what else comes apart or is it a case of driving the bearing out from the inside?

Any info would be appreciated as I know as a retired engineer these jobs can become epic.

Hi Mark...

Just curious...

I have Parker 27 #138. I have put quite a few miles on it over the years. How did you determine that you need a cutlass bearing?

Thanks

Marv Kowalewski

---

Hello Mark,

I have a P27/136 and replaced the cutlass bearing around 7 years ago. The shaft / prop was 'rattling' with around 0.5mm play.

My inboard end seems a little simpler than yours with a oil filled stern gland which has three lip seals inside - one to keep the sea water out, then two forming a small circular compartment around the shaft which is filled with a light oil, topped up by gravity from a small (0.25L?) plastic container of the oil. Usage of the oil is tiny - drops per year so far!

Removing the shaft was simple once the 'bond' of shaft to engine back plate was loosened whereupon the shaft was withdrawn from the boat complete with prop. The old bearing was much harder - removing the grub screws did not release the sleeve and a home made puller would not grip the inside edge of the bearing - nor would a rod pushed down inside the shaft tube.

I eventually cut the bearing longways with a hacksaw blade fitted with a 'pistol' handle - two cuts were necessary about one cm apart so a bit could be prised out allowing the remainder to be compressed and removed.

The new one was simple to fit, and I had to replace all of the lipseals in the stern gland as they were damaged.

The new bearing has given no trouble since replacement.

Best of luck!

Chris

To answer Marvin's question the surveyor who conducted the pre purchase survey commented that the Cutlass bearing would need replacing within a year or two at most.

Last winter I had the boat ashore and measured the play in the bearing which was about 0.5mm+ in the vertical plane with little or no movement laterally.

From data on the internet relating to the acceptable tolerances for the type of cutlass bearing installed this put the bearing out of tolerance in the vertical plane and hence the need to replace it before substantial wear might give me a bigger headache.

Chris,

Thanks for the info. As an aside thanks for your info last year regarding my six to one keel lift which is working a treat. Re the cutlass bearing my local yard suggested that at the prop end, once the shaft and the grub screws have been removed , that the external boss might be unscrewed which in itself might pull the bearing out to a point where one could get hold of it or at least reveal the tail end which might be grabbed.

I am a bit dubious about this as if the whole tube starts to turn, (the inboard end appears to be screwed into the original stern gland fitting to which the PSS seal is attached) I will have a much bigger bedding in problem to resolve.

When you removed your bearing was is bedded in with anything. Also when fitting the replacement was it an interference fit or just a slide or push fit?

Did the grub screws come out OK? Any tricks you learnt on the way would be helpful.

Hey Mark...

Thanks for the info re the cutlass...so I guess I just have to get under the boat and grab the shaft and wiggle it....so will do just that.

Open for more help?

Referring to grub screws...where are they located on my 27.

Referring to Chris's 6 to 1 keel lift...I lost that article and wonder where it may be located.

Many thanks,

Marv

---

Marvin,

The article re the six to one lift keel has been uploaded to the articles section of the PSSA site.

The position of the grub screws may depend not the type of stern tube and fittings used which may differ from mine. If you look closely In the photo I posted of the prop end you can see the starboard screw at the three o'clock position on the boss. The port screw is opposite it.

Hi Mark, Marvinj,

when I did my cutlass bearing the prop shaft was removed (complete with prop) - the stern tube stayed exactly as fitted - hence the need to remove the stern gland/seal and slide the prop shaft out from the stern.

My cutlass bearing grub screws were fitted same a yours - 3oclock and 9 oclock. I suspect the damage I did to my original lip seals was due to the sharp edge at the inboard end of the prop shaft - which I rounded off when refitting.

rgds

Chris

Chris,

Thanks for the info. I suspect I will have to cut the bearing out as you did. I may elect to do this straight away to reduce the time and effort. Instructions for fitting the PSS seals indicate that all rough edges should be removed from the shaft so I will attend to this while the shaft is out. I have procured a PSS repair kit ( seals, grubs crews, locking fluid etc) for just over ten quid so will not chance having to do this part of the job twice, hopefully!

Mark, I replaced my Cutless bearing the beginning of last year. I had to cut it out using a cut down hacksaw blade in an air saw to cut it along its length, I was then able to lever up an edge, and twist it out. You should be aware that there is also (or should be) another half length cutless bearing at the inboard end to prevent shaft whip due to it's length, I drove this out with a length of 1" inch angle iron to which I had a small length of tube split and then re welded to a slightly smaller diameter than the internal bore of the shaft log. This inner cutless bearing is also held in with two small grub screws oriented at 3 oclock and 9 oclock, the same as the aft cutless bearing. They are inside the length of the shaft log that is covered by the rubber end of the DSS Seal. In my case it was very badly worn, completely smooth with no grooves left. I replaced that with a paxolin encased shaft seal , cut in half so that I have a spare.

I had a problem that the brass outer of the original cutless bearing had been eaten away quite extensiveley (about an 1" inch) probably due to electrolysis, so when I replaced it, I lengthened one of the grub screws so that I could put a stainless locknut on the end and had a small 1" wide piece of stainless welded on to the stub keel that protects the prop, with a matching M6 hole in it so that the grub screw passed through the hole and then into it's theaded hole to nip on the cutless bearing. I then put a 2 1'2" dia shallow zinc anode on the stub keel. this seems to have worked as there is no sign of corrosion on the edge of the cutless bearing and the zince is showing that it is depleting therefore working. Interestingly, despite having a good stout 10AWG wire from it to the engine block, the main anode is not depleting at all although the stub keel anode and the nose cone anode on the the featherstream prop are both showing about 40% attrition after one season so both replaced. I am considering removing the large anode as it does not seem to be doing anything. It certainly cannot protect the three through hulls as they are much to far away and cannot 'see' the anode and in any event, I am due to change those to Forspar Marelon through hull fittings so they will not need any protection. I did not use a paxolin cased cutless bearing at the rear as I was advised against it. they can swell due to constant immersion and be a pain to remove as unlike brass, they cannot be bent out of shape to withdraw. The inboard end is ok as it is possible to get a long length of something up the log from the rear to drive it out.

Whilst I was at it, I replaced my Volvo shaft seal and before I fitted it, I modified the clamp with a piece of thick wall 10mm OD stainless tube welded on to it drilled through the clamp and then a coresponding hole drilled in the rubber of the shaft seal and the shaft log itself. To this I fitted a length of tube raised above the waterline and clipped in that position. This allows air to vent freely from the shaft log via the tube and thus I no longer need to remember to burp the valve seal when the boat has dried out. If I recall, I had to drill through the half cutless bearing as well to provide a through flow of air, but it was simple to do. If any one else wants to do that, ensure to drill a 10mm hole in the clamp and weld the piece of tube with about 4mm projecting through the inside. this allows the clamp to locate through the seal rubber and also the shaft log, both of which should be drilled with a 10mm hole.

---

Ran out of letters in my last post so continuing here, You should be aware that if you replace the inner cutless bearing (advisable) you will need to realign your engine as the old one will likely have worn down particularly on it's lower face due to slow settling of the engine bearers over the years. When you get to do the realignment, make sure that the boat is in the water in sailing trim or at least ensure the rig is up and tensioned, as the boat distorts slightly with the rig tensioned and also when in the water. This causes the shaft alignment to change.(ask me how I know)

Someone mentioned trying to drive out the old main cutless bearing from the inside, this can only be done with the engine removed, so I tried it when I did an engine swap last year. That's how I discovered the inner half cutless bearing! This also prevents you from driving out the main cutless bearing from the inside.

---

Martin,

Many thanks for the detailed explanation. I was certainly not aware of an inner cutlass at the shaft seal end. I don't know if my setup has one of these as the PSS seal is attached to the remnants of the original traditional packed gland. I will not know until the boat is out of the water come April. I may email Richard Watson to check if there is a seal end cutlass as he fitted the PSS shaft seal. In any case forewarned is forearmed. I will try to remember to take some photos at the time and post them for future reference of others on the forum.

Cutlass Bearing Update.

Thanks to all who contributed to my post. Here is what actually happened for future reference.

Firstly, they are not all the same (see attached Photos of the fwd and aft ends of the stern tube.

The fwd end is slightly oval, probably due to engine misalignment over time (the play at the cutlass before replacement was vertical only). Diameters at the fwd end were 1.030" horizontally and 1.092" vertically.

To remove the old bearing I cut two slots in the rubber and then chiselled out the rubber strip with a screwdriver before using a single ended hacksaw to cut the brass outer below the right hand grub screw. Removing the rubber helped with the feel of the cut. When almost through along the length I twisted the end and used a broad screwdriver blade to carefully split the outer without damaging the stern tube.

A quick polish with 3M scourer and the new bearing was a push fit without the need to revert to a hammer and block. Measured diameter and length at the aft end were 1.51" dis and 3.96" long recess.

Before fitting I chased the grub screw threads (with an 8mm tap) to ensure they would grip the new outer.

Once fitted I realigned the engine by slackening off the rear mounts and adjusting each side by the same number of turns until the R & D Marine Ltd. coupling just slid onto the mount bolts. To ensure alignment the shaft was shimmed at the fwd end of the stern tube using hard plastic shims to ensure it was central. Before alignment the connecting bolts were about 5mm high.

http://www.randdmarine.co.uk/flexiblescinst.asp ) was 0.090, 0.065, 0.050 and 0.068 at 90 deg intervals going clockwise. Post alignment they were 0.070, 0.065, 0.065, 0.068 (within the 0.010 tolerance stated by the manufacturer.

The PSS seal was then refitted and hopefully there will be no leaks. Launch tomorrow.