Sunday, July 19, 2015

Removing The Cutlass Bearing - or - I Need To Work On My Planning

I don't recall if I mentioned this already (boy my memory is failing lately), and with the slow internet here I'm having a hard time checking the older posts...so bear with me if any of this is repetitive...

After finally getting the through hulls reinstalled on the boat (I still need to connect hoses...but wanted to let the sealant have plenty of time to cure), the next task was one we discovered after hauling the boat out.  Yep, you haul the boat for one project and seem to find a few more that need to be done.  This next task is to replace the cutlass bearing on the starboard engine.

For those who are not familiar with such things, a boat with an inboard engine and no sail drives has a long shaft that extends from the drive shaft of the engine downward at an angle through the hull and on to the propeller in order to make the boat move under power.  In addition to a good seal to keep the water out, this long shaft needs a little support so it doesn't go flailing around from the forces generated by the propeller and end up cutting the back end off the boat.  This job of holding the shaft in place is performed by the cutlass bearing.  The bearing is a nitrile rubber sleeve type with a hard outer shell and is found near the propeller end of the shaft. The combination of this bearing and the coupling on the engine keep the shaft spinning along a constant axis.

The cutlass bearing is in the sleeve where the shaft enters the boat.

Naturally, as with many things found on a boat, these items wear over time.  When we hauled the boat, we checked the shaft by wiggling the propeller up and down to see if there was any movement. We heard the clunk of the shaft moving, which indicates it was or soon will be time for the bearing to be replaced.  Since we already had the boat out of the water, now seemed like the right time to change the bearing.  While it is theoretically possible on a Leopard to replace this bearing with the boat in the water, it should be far easier to do as we sit on land.

In order to replace the bearing, we first have to remove the propeller.  Given the importance of a propeller remaining attached and all the forces involved in it pushing the boat along through the water, it is usually well attached to the shaft and requires a special device to aid in its removal. A propeller puller (gee, how did they come up with that name) helps pry the propeller from the shaft much in the same way a gear puller removes gears that are pressed onto a shaft by grabbing the forward facing hub of the propeller and then clamping against the aft end of the shaft to squeeze it off.  The reason why I'm telling you about this is...well...because I don't have one.  If you carried every possible tool needed to work on a boat with you, I'm betting that your boat would not remain afloat. So some things, particularly more rarely used tools or ones you are not likely to need while underway, have to be assumed that you can find at the average boat repair yard.

This is where my planning comes into question. I'm sure the boat yard where I am hauled has one or more of these handy tools since they work on boats every day and several they are working on are sans propellers.  But, with the push to get all our through hulls installed, I lost track of time and didn't think about this critical tool until well after 5 PM on a Friday.  Just a little too late to see if I can borrow one...at least until the shop re-opens on Monday. The same Monday when I had hoped to march into the shop with the bearing sleeve and new bearing in hand to have them press out the old one and install the new one. Not knowing how difficult it might be to remove the prop or the bearing sleeve, I really wanted a portion of the weekend to work on it.

So, Saturday morning we started looking for a prop puller.  Went by the marina office and got the official story that the shop guys wouldn't be back until Monday and the receptionist doesn't know where...or what...one is.  Checked several nearby marinas and boat yards to see if they had one to borrow or rent, but had no luck. I considered the option of trying to make one, but with the forces involved and the chance of damaging an expensive bronze propeller, decided that would not be the best idea. Went to several auto parts stores to see if they had something that would work (some auto parts and hardware stores around here carry marine stuff) and even looked at a couple of gear pullers. I was worried, given the forces that are reportedly involved in extracting the average prop, that the small hooks of the gear puller might put too much force on a small point on the propeller hub and be able to damage the soft bronze.

Here is where a friend and fellow Leopard owner I met in Georgia saved the day.  He had offered to provide some tips on this whole process, and when I called to talk with him he said he uses a gear puller.  When I mentioned I had looked at some and was concerned about the hook size, he indicated he never had a problem and would send me some information on the model he had.  A few minutes later he called me back and, not only did he figure out the model, he found that the local AutoZone had one in their free tool loaner program and had reserved it for me.  He also explained that if you don't use too much force at one time and just take it slow (a 1/4 turn of the clamp at a time and maybe tapping it gently with a rubber mallet), the prop should work its way off with no damage.

Gear (propeller) puller from AutoZone

I also heard, with the forces involved, that it was recommended to thread a nut on the end of the shaft to prevent the propeller from flying off once it released its hold on the shaft.  My friend said he never had that problem with his technique, but I figured I would play it safe and get a nut anyway (I couldn't just use the prop nut because the puller didn't have a long enough reach to work around the big prop nut). So, when we went to the store to pick up the puller, I also asked if they had this large metric nut in stock.  Of course they did not.  As it turns out, neither did the other auto parts or hardware stores that were in town (I guess a M20x1.5 nut is pretty rare, the closest we found was an M20x2.5 [bigger threads] at Tractor Supply).  So much for playing it safe.

So, about 8 hours after the odyssey to find the puller started, I was headed back to the boat with something that "should work".  I carefully placed the puller around the prop with the three arms going between the three blades of the prop, centered everything, and tightened the screw up snug so the puller was attached but not yet "working".  I then tightened the puller a quarter turn with my wrench. I went to get my rubber mallet (naturally I left it a little out of arms reach...what was that about my planning again?) and when I returned it looked like the propeller had moved.  I checked and sure enough the puller was loose and so was the prop. I removed the puller (being careful not to let any of the arms ding the prop), then slid the prop off while making sure I didn't drop the prop key (a small stainless steel bar that fits in a slot in the shaft and the prop to keep them oriented).  Yeah, about 8 hours to find the tool, and about a half hour to actually remove the prop...with most of that time spent bending the locking washer back out flat so I could remove the prop nut.

It was finally time to remove the cutlass bearing sleeve containing the cutlass bearing. The sleeve is just a stainless steel cylinder that contains the bearing with a teardrop shaped flange welded to it.  At the top of the teardrop is a single large bolt that holds it in place.  The theory is you remove the bolt and slide the sleeve out.  Yep, that's the theory.  I don't know if the factory originally did this or if it was a prior owner, but the sleeve is glued in place along the flange with some sort of sealant.  So the actual process is:

  • Cut the sealant and paint between the flange with a utility knife as best you can without damaging the fiberglass.
  • Remove the bolt.
  • Use a flexible putty knife to try to cut through the sealant between the hull and the flange of the sleeve.
  • Use a sharp, stiff blade scraper/putty knife or painters tool and a mallet to gently cut through the sealant and pry it away from the hull.
  • Curse and question the lineage of those who designed this part of the boat or at least used sealant on it.
  • Continue to try to work the sleeve out of its resting place.
  • Attempt to spin the sleeve around by the flange to convince the last bits of sealant to finally let go.
  • Use screwdrivers or pry bars (with wood backing against the hull) to get a bit more leverage and continue trying to persuade the sleeve to come out of the hull.
  • Stick a dowel or screwdriver through the bolt hole in the flange of the sleeve when it is spun sideways to get more leverage as you work the sleeve back and forth and slowly extract it from the hull.
  • Once the thing is finally out, have a beer...you earned it.

Everything removed.

Ok, so it wasn't quite that bad.  Honestly the actual working time for the removal of the prop and cutlass bearing sleeve was a couple hours.  The vast majority of the time on this project thus far has been spent researching how to do it and finding the needed tools (prop puller) to do it. And a special thanks to my friends Fred and Lee as well as the other Leopard owners on the LeopardCat forum for all the help and advice!

From left to right: The prop zinc, nut and lock washer, key,
propeller, sleeve retaining bolt, cutlass bearing in sleeve.
All freshly rinsed from a little downpour.

Now that the bearing is off of the shaft, I can see that the reason for the cutlass bearing wear is that the shaft...or the bearing holder sleeve...seems to be misaligned. The bearing is worn at the top on the aft edge and the bottom on the forward edge of the bearing.  So, I guess I'll have to research how I can resolve that while I wait for Monday so I can get the yard to use their press to remove the old cutlass bearing and insert the new one.



6 comments:

  1. The nut you wanted for safety could have been done with 2 zip cable ties. But your prop did not jump off.

    Sorry I am missing all the fun!

    Cheers

    Roscoe

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    Replies
    1. Interesting trick with the zip ties...will have to remember that one. Living on a boat on the hard isn't what I would describe as fun though...especially in this heat.

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  2. Hi Mike,
    I have heard that the shaft alignment can only be accurately done when the boat is floating as the hull will deflect because of the pressure points from the supports.

    Wild theory.......
    How much sealant is inside the stern tube? Perhaps the shaft is in alignment when floating but the cutlass bearing was held out of alignment by the sealant.... If a lot of sealant was used and set while the boat was on the hard (and shaft out of alignment because of the deflection) then once back in the water, the shaft returned to normal state, but the cutlass bearing was held out of alignment by the sealant.
    cheers,
    Alan

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    Replies
    1. Hey Alan,

      You are correct that ideally alignment should be done with the boat sitting in the water for at least a day. The catch is that there are some things that can only be adjusted on land, during assembly (or original build). Basically there are two different alignments and one is rarely considered since there is usually very little you can do about it. The one you can usually adjust is the engine to shaft alignment. The other is the alignment of the shaft in the shaft log (tube), seals and bearings.

      Of course, your "wild theory" actually touches on the other alignment issue. The bearing holder, since it comes out on my boat, could theoretically become mis-aligned compared to the idea path of the shaft through the boat. Excessive sealant or it drying while the boat is hanging could cause this. An overzealous mechanic or prior owner could have slightly bent something along the way or forced the holder in to the log slightly cocked so it doesn't quite point in the right direction (the flange on the holder did seem to have a very slight bend in it that could cause the wear encountered...and we corrected before pressing in the new bearing). This is the alignment stuff that needs to be thought of before it goes back in the water...and as I hinted at, am doing my best to see if I can get as right as possible before it goes in.

      After that, the only thing to do is launch the boat, let it sit, and then do the engine-to-shaft alignment and hope the result resolves the issue. I think it might...and so I am heading in that direction.

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  3. Hi Mike,
    Cruising World has several online articles on cutlass and bearing removal- although they are usually for monohulls and boats with struts. Many of those call for the removal of drive shaft which doesn't seem to be needed in your case. Perhaps you've already read the articles. Sounds like you are well on your way. Hope it cools down and good luck.
    Doug in VT

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    Replies
    1. Hey Doug,

      Yes, I consulted the Oracle (google) before starting this...or for that fact most any...project. In this case, the better information was found on the LeopardCat users group.

      The shaft doesn't need to be removed and, in fact, it can be done in the water (although I would imagine that would be a big pain in the butt). It has all worked out rather well actually...except for needing to check the alignment once it is back in the water.

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