The new propeller. This was actually a 12 inch diameter wheel that was cut down to 11 inches. The 12 inch probably would have worked OK, but I did not want to cause excess vibration due to lack of clearance. Apparently prop shops do this sort of trimming all the time; they did not charge any extra for this.
With the rudder to one side, this prop will come off the shaft and out of the aperture without moving the engine or shaft forward. Just barely.
For a good vibration free fit between the prop and shaft, I used a lapping compound.
The propeller has 13 inch pitch, and seems a perfect match for the engine. Switching from two blades to three made a big difference in the boats backing characteristics. I can actually control the boat in reverse now!
file:/root/Desktop2/FinishedWoodwork.jpg
What is wrong with this picture?
Aside from being very large, the zinc sits too close to the shaft tube. When in gear, the prop thrust moves the engine forward on the flexible mounts, causing the zinc to bear against the shaft tube. Of course, the shaft tube should not get such a loading.
After I realized this was happening, I removed the zinc, thinned it down a little on a lathe, then replaced it on the shaft, but almost touching the prop hub. This solved the problem.
I don't like taking my hand tools into seawater. Afterward I washed them thoroughly in fresh water, then dried them and sprayed them with WD-40.
The Yanmar comes with an engine panel, which you can see here. I plan to someday place it behind a Plexiglas (perspex?) panel, possibly in a different location. I plan to move the stop pull knob too, as it catches lines and has a steel (rustable) shaft. You can mount it anywhere.
The control lever replaces the original two lever Morse control, which had worn out. This one was made to fit on the side of a pedestal I think, but it works perfectly here.
I used what I would call medium quality control cables, but I think next time I will use better.
This shows the finished woodwork. I had to move the steps up slightly, but not really forward any. Below the lower step I built a shelf with a fiddle, which covers the pre-existing access hole.
Friction and interlocking parts hold the removable parts together quite well, although I may eventually put a hook and eye on the top step just for added safety. quit
The front panel keeps the top step from sliding with its top edge captive in a slot routed on the bottom of the upper step. The trapezoidal piece you see above the step in the above photo slides in from the side, holding the step down.
Here you see the shelf and fiddle, but both steps are removed, along with the access panel. The shelf comes out also, for access to the bilge and the electric pump.
Now if I can just figure out how to get the deck clean. I probably should have taped some builders paper to the deck before I started. Oh well... Next time.
Well, that's it. Was the transplant worth it? Absolutely.
The engine starts instantly, and never misses a beat. It vibrates much less than the old one, and if you go forward on deck while the engine idles, you can hardly sense that it is running. The boat accelerates much more quickly, in forward or reverse, and is much easier to handle when mooring or docking. Top speed is higher than with the old engine. Fuel economy is excellent. The exhaust smells clean and is invisible. The increased space makes maintenance easier. It is also possible to clean this engine space now, because there is enough room for a scrub brush.
Do I think others should do the same? Maybe.
It takes four things to accomplish this sort of job: money, time, mechanical skills and commitment. Plus the ordinary assortment of hand and power tools. If you have got all that, then I would say go for it.
Thanks to those who helped me: John Lopes, Paul Diette, Bill Raposa, and the staff at Old Port Marine, Newport, RI, USA , who supplied the engine with lots of invaluable advice.
PS: The old engine will soon start a second career, powering an hydraulic log splitter ashore, owned by one of the boatyard workers.