problem diagnosis needed, no speed, smoke, low rpms
I'm relatively new to sailboat maintenance and I've got problem. My engine is a Yanmar 75 turbo with a hurth v-drive and maxprop. boat is csy 44. I've been on a mooring for 5 months at st augustine and have not done any bottom maintenance since we arrived and planned on doing so only when we were moving the boat. I took the boat out for a short spin yesterday and could not get 1/4 knot of speed and would not tach up over 1500 rpms. I saw black smoke and some oil spitting out of the exhaust when trying to rev over 1500. The engine usually cruises at 2700 rpms. I dove under the boat very briefly due to very cold water and saw about 20 barnacles on the prop, small, but nothing that would cause that kind of performance. It seems like the shaft is somehow restricted. I didn't immediately see anything caught on running gear, but again, it was very cold. The speed was fine upon arrival in st augustine in August. I expected performance loss from growth, but not rpm restrictions. In neutral, it will tach up no problem. I have not changed the fuel filters yet. The performance issues are the same in forward and reverse. I will be under the boat tomorrow with a wet/dry suit and have more time, what should I look at? During the summer we were having a significant shaft vibration, I'm thinking maybe the cutlass bearing is going bad. Any thoughts would be appreciated.