Propeller | Shaft | Strut & Bearing | Stern Tube & Stuffing Box | Coupler & Drive Savers | Alignment
Inspect the Strut, Replace the Cutlass Bearing
or "Be Proud of Your Strut! "
- Poor bonding or letting zincs go too long
- Lift the boat with the straps on the strut
How to kill a Cutlass Bearing:
- Just wait, they die on their own, but you can hurry the process with:
- Poor alignment
Strut and Cutlass bearing–
Many older full-keel boats don’t have a strut at all, they are mainly found on powerboats and newer fin-keeled boats. If you don’t have a strut, ignore most of this, but do check out your cutlass bearing. It is first thing that wears out in every boat's drive system, and can be a good early warning for major alignment issues that could cost you a new shaft down the road.
Carefully inspect the cutlass bearing and see if the rubber is still intact. If your engine is badly aligned, or you don’t know when the last time you replaced it, now is the time for a new one. Some indicators are the rubber is worn so you can’t see much of the grooves, or part of the rubber is missing or melted. If there’s no rubber, you were SO close to wearing your shaft in half or having it bind up in the strut and rip a hole in your boat – be grateful you caught it and replace it now.
The easiest way to remove the cutlass is without the shaft in place, cut the bearing in half lengthwise with a hacksaw blade or a sawsall (always cut UP into the strut) and tap it out using a punch or a special tool made out of a piece of round stock with a point and two flat edges.
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| A homemade tool for removing cutlass bearings |
Once you put in the new cutlass bearing, check if the strut is pointed in the right direction. If it’s visibly off, you need to re-bed it. If you don’t do this, you will keep buying new cutlass bearings and shafts. At the yard we put a laser in it and a piece of tape in the stern tube, and see if the dot’s in the center. If so, you’re fine. In the absence of high tech, try to sight down where the shaft would be, you want a clean shot all the way to the coupler. Insert the shaft and make sure (by hand!) that it spins freely in the bearing. Check for corrosion. There’s a lot of metal in the strut, so a little pink isn’t the end of the world, but if the metal is missing bits, and/or very brittle, consider replacing it before it snaps off on its own.
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| A shaft that has been worn by the cutlass bearing from a bad alignment |
A quick note on installing cutlass bearings, do not hammer the metal. Clean the hole so it goes in properly, press it in with a threaded bit of rod with a nut on each end, or if you MUST pound soften the blow a little with a piece of wood to protect the bearing. If you mushroom the bearing, you can still salvage the job by getting most of the bearing in then cutting off the mushroomed part that sticks out. This is not the right way to do it, but it will work in an emergency.
Installation tips:
- Don't hammer!
- Freeze the cutlass bearing so it shrinks a little
- Clean the strut hole very thoroughly, try red 3M scrubber
Next we will look at the stern tube and stuffing box
If you haven't checked your shaft, check it out now
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