I have a 1993 Hunter 30T with a Yanmar diesel auxilliary, I believe it's rated at approximately 16 horsepower. The prop is the standard two- blade fixed prop that came with the boat. Yesterday, when docking, I slowed the boat as usual by going into reverse. When I found I had slowed a bit too much, I went back into forward gear, but nothing happened. I added power to the engine and it clearly was not under load. I then went back to neutral, then forward again with the same result. I repeated it once more, but this time, after I added power right after shifting to forward, there was a slam-thunk type of noise and then I was in forward gear. I try to slow to idle each time before shifting gears to protect the transmission, but I don't know how the previous owner treated the engine. I never had this occur previously. Do you think this is a sign of a serious transmission problem?
Mark Matthews responds:
Thanks for the question. There are a lot of times when its not easy being the boat doctor from the other side of the screen. This is one of those times. Without seeing your problem for myself, I can tell you that there are a number of areas to examine before you start any major transmission repairs. For starters, make sure that the shift lever is moving the transmission through its full range. Check the shifting cables and their connections to the shifter and the arm on the transmission. Any broken, slipping, or kinked or suspect cables need to be replaced. It could be that your cables are intermittently slipping and engaging the transmission, resulting in the slam-thunk noise.
Youll also want to check the transmission oil level. Most transmissions have a dipstick. If its low, add oil. Youll also want to check to make sure that there isnt anything wrong with the coupling bolts or that the coupling isnt shifting on the propeller shaft, and that the key hasnt slipped out of its keyway. Finally, dont rule out the prop, which could be fouled or damaged. If none of these seems to be the culprit, your transmission may need professional help. Good luck.