There is nothing sensible about owning boats. Which makes them so much fun!
I rebuilt my YSM12 four years ago (yes crouching in the vberth), and it was running just fine, but engine parts are getting harder to find, and I had a five year plan for the boat. And as well, I needed a new prop. May as well replace both now and get the value out of a new engine, and a prop that spins the more typical direction. Buying another boat can be a year of surprises and extra cash, so I went with the devil I know.
I would not have replaced the engine if I was sailing locally and just to the Gulf Islands. The YSM12 would have been fine. But I've been up in the Discovery Islands, and going further next year, northward with less wind, and when going through the tidal passes, speed and reliability are welcome. I sail year round so I will get a lot of use out of it.
Briefly, the Beta 20 engine is lighter than the YSM12 by about 100 lbs. It took about 40 min to pull the YSM12 out (with the head off) through the vberth hatch, and about 20 min to drop the new Beta 20 (which is smaller) in the same way. We used a forklight with a rig at the yard. There are a lot of modification needed to support this swap for my boat. And doing it myself it took longer than I expected. I sold my old engine so that helped a bit.
If you're interested in this you can download the install guide from BetaMarine, and see what is needed.
I like the swap. It has a lot more horsepower, most of which you don't use. In a strong head wind though, it is helpful and welcome to have. And it can cruise at 6 knots for hours if desired, and is quieter and less vibration. But you can cruise at 5.5 knots at a relatively low rpm and is quite enjoyable. I went with a fixed three blade Campbell Sailor prop. There have been 4 Beta swaps this year that I've heard of into Yamaha 30's locally. Two were Beta 16's (2cyl) and two were Beta 20's (3 cyl). I upgraded to a 75amp alternator, and added a hot water tank heated with the engine.
While I know other Yamaha 30's have done the swap I would be grateful if anyone can put me in touch with them.
Thanks all!