Stern Tube Installation Rework
Friday - October 29, 2004•Views: 7699••
My boat started developing a small leak around the stern tube so it was time to rebuild the whole area. The removal was an incredible pain on the 31 because you have to go straight down into the engine compartment head first to remove the nuts that hold the stern tube in place. This is because the bolts go from the outside through the stern tube flange and into the rear of the keel. On the inside there is a washer, lock washer and nut. Much to my surprise, there was only a set of washers and nut on the top bolt. The bottom bolt was simply threaded into the fiberglass and was too short to have ever had a set of washers and nut on the inside. I also found there was only about 1/16" overlap on the sides of the stern tube flange and the fiberglass. It was not a comforting feeling seeing how poor of condition the whole installation of the stern tube was done.
For the rework, I removed everything, cleaned the area and expoxied up the bolt holes and added a layer of epoxy all the way around the inside diameter of the hole making it smaller. Once the epoxy cured, I used a Dremel to grind the hole to the exact size of the stern tube to make for a snug fit and giving me almost 1/4" overlap between the fiberglass and the stern tube flange. For the bolt holes, I redrilled them smaller than the bolts and then tapped them to give a decent set of threads in the epoxy. These threads are only to hold the bolt inplace for the assembly process. I purchased slightly longer bolts and slotted the tips with a Dremel and small cut-off wheel for a screw driver so I could thread them from the inside out (all done through the stern tube hole). Then I reassembled the stern tube with washers and locking nuts on the outside. It made for a much easier reinstall and will make future maintenance easier. I was also fortunate in that I did not have to shim my stern tube to get the shaft alignment correct!
I did check on getting a threaded backing plate, but the factory didn't supply them for the IP31.
For the rework, I removed everything, cleaned the area and expoxied up the bolt holes and added a layer of epoxy all the way around the inside diameter of the hole making it smaller. Once the epoxy cured, I used a Dremel to grind the hole to the exact size of the stern tube to make for a snug fit and giving me almost 1/4" overlap between the fiberglass and the stern tube flange. For the bolt holes, I redrilled them smaller than the bolts and then tapped them to give a decent set of threads in the epoxy. These threads are only to hold the bolt inplace for the assembly process. I purchased slightly longer bolts and slotted the tips with a Dremel and small cut-off wheel for a screw driver so I could thread them from the inside out (all done through the stern tube hole). Then I reassembled the stern tube with washers and locking nuts on the outside. It made for a much easier reinstall and will make future maintenance easier. I was also fortunate in that I did not have to shim my stern tube to get the shaft alignment correct!
I did check on getting a threaded backing plate, but the factory didn't supply them for the IP31.
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