Grand Banks Classic Cutlass Bearing repair

During John’s trip from Lulu’s to Demopalis he noticed several problems with his new boat.

First was excessive engine movement. I mean both engines might have fallen over in big seas. John’s 42 has twin Cummins, so it has some horsepower. It seems the thirty year old motor mounts had failed. The local boat yard mechanic, who does boat work as a second evening job, quoted John $40/hr to change them out. Rob and I had changed his in a day, even with Rob helping me. These guys did both John’s engines in four hours with impact tools. They hauled ass. A week later they aligned the engines.

Alas, the clunking sounds did not go away. Best guess was the deteriorated motor mounts had allowed the prop shafts to destroy the cutlass bearings. This is a perfect example of cascading failures. Motor mounts are cheap. When they go everything they effect goes too. Transmission bearings, dampner plates, shaft logs, cutlass bearings, prop shafts, etc, etc. Those are not cheap.

What started the tear down was lack of cooling water to the packing gland. Removing the water line from the exhaust showed rubber blocking the elbow into the gland from deteriorated cutlass bearings.

John’s 42 Classic has three bearings per shaft. One in each strut, one at hull entrance to shaft tube and one at exit of the shaft tube.

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John decides to fix it himself, time to reflect. It is summer in Demopalis, 100+ degrees in the shade, 1000% humidity. Let’s go do bottom work!

During tear down it was quickly discovered that the prop shafts had crevis corrosion and had several cracks along the 20+ foot 2″ shafts. This was probably the result of the boat sitting for several years. So an order was placed for two new shafts, ouch.

The cutlass bearings assembly with black hose and the forward half containing the packing gland removed.

The arrows : A) the bronze tube containing the cutlass bearing. B) the fiberglassed in hull bronze tube same as A. C) the very worn cutlass bearings. Looking closely you can see the bronze interlocking tabs protruding.

The yellow circled pieces are the removed packing glands assembly. They are positioned to show how the the cutlass bearing half and the packing gland half interlock. The two halves are connected and sealed by the rubber hose previously shown.

The part touched by the finger fits into the cutlass bearing tightly and allows the bearing to be pulled out evenly under pressure.

To give John credit, he researched this enough that he started designing his own tools. It took about a week of pestering a local machine shop, but after several tries he eventually ended up with a stepped disc that fit into the bronze shaft tube molded into the hull, and would allow John to pull the cutlass bearings out by using a big, long-ass all thread rod with a big washer and nut at the other end.

The yellow tube is in place as a spacer to pull against and a receptacle for the cutlass bearing to go into.

In the last picture the flat stepped washer shown is mounted backwards, John was tired….

Due to space limitations, John could only turn one nut flat at a time, so it could take hours to slide the bearing out, under great pressure. A cheater bar was required on the wrench to gain the leverage needed.

There were a few issues. One of the tubes had a glob of fiberglass resin in it that had to be chipped out.

Also the shaft log bearings had set screws to hold those bearings in the shaft log. So he had to grind the fiberglass away till he could find the set screws and uncover them. The second screw is 2 1/2” behind the first one, in line.

The new cutlass bearings were kept in a deep freeze for a couple days, then gently pressed in. Reassembly was rather quick, just a couple hours each side.

Once splashed, we decided to sea trial his work BEFORE taking a week trip upstream to Nashville. While backing out of the slip, I could hear a distinct ticking from the drive train. We quickly killed the engine and pulled the boat back into the slip where I decided that the shaft cutters were out of adjustment from the work being done, and touching on each revolution of the shaft.

John was chosen to jump over the side to fix it, it was his boat. Here he is playing Navy seal.

A great job and alot of information here in case you decide to tackle this yourself. If possible do it in spring or fall, under cover, with A/C units to cool the boat down. John also designed his own Jethro Bodine A/C system from Walmart for $100. We were having consecutive 100 degree days.