So, it has to be the size of the shaft in relation to its length, its a bit too much to handle the higher torque of the new motor and stress of pushing the boat.
I did notice the boat travels at a higher speed now. With the old motor and same prop it did around 7.5 kt full out. Now it gets up to 8.5 kt. full out and cruises at about 7 kt @ 2600 RPM's. I've now gone with a feathering Maxprop 3 blade, which didn't change the speed but does back up real nice now.
The original prop that came with the boat. Very sloppy!! It was pitted so bad I gave it a coat of epoxy and painted it until I ordered a new one.
The new prop. Very nice for a folding prop. It performed well and was totally quiet. But now, I have a new prop that doesn't fit the shaft anymore and I need to sell it.
The old stern tube with the old motor.
Stern tube w/o the motor and running gear.
The old stern tube exiting the hull.
The original people who installed the old stern tube did a really bad job of it. The under side was nothing but filler, no glass or resin sealing off the gap. As I ground away water started coming out and ran for a while. So the foam core had absorbed a bunch of sea water and I had to let it dry out.
I dug out a lot of the cheap filler and had to use an air chisel to get the major portion out.
The hardest part was getting all the old filler from between the hull skins and back to the foam.
To get the tube itself out I drilled holes straight down, all the way around the tube, then went back with the drill and worked it back and forth elongating the holes until they over lapped. Then used a carbide burr to finish it off.
View from inside.....................
The old tube. Lots of glass on the inside hull, nothing on the outside hull. What were they thinking???
I made up my own new tube 20" long using epoxy and 4" wide, 6 oz glass. Made a ring of G-10 to butt up the new filler.
The bottom side. Made a couple guide plugs to go between the shaft and tube for alignment. Used a wood carbide tip forming wheel and carbide burr to fair in the edges for the finish work.
Started filling in with a glass-filled polyester paste. Had to do little bits at a time to keep it from shrinking and cracking.
Then faired and ground smooth.
And epoxy/glassed over both sides with some 10 oz and 6 oz.
Faired in and painted......................
To get the prop shaft out w/o having to pull the rudder I went to a two-piece strut, which was a whole job in itself, it was replaced while replacing the motor. I fine tuned it and added extra fasteners to eliminate any movement.
The old strut had lots of pitting and the bearing was loose in the strut hole. I had to use bronze machine screws to hole the bearing in place.
After a coat of barrier coat...............
Fairing in the strut for a second time and changed the bearing size to 1-1/8" to match the new shaft I had made.
Glassing over the filler..................
Barrier epoxy over the glass.......................
As I was laying on the barrier coat some of it managed to get pass the tape job and ran down the inside of the new bearing, glueing the shaft to the bearing. So, after spinning it loose I made a puller with a split sleeve and pressed out/in the bearings.
And now, the new prop, a Max-Prop, 3 blade, feathering. 18" w/12.2 pitch.
After all this it finally runs like a dream. No vibration and backs up like never before. This made the boat a real pleasure to operate under power.