Posted by Nick Wigen (12.212.0.156) on July 19, 2003 at 14:22:29:
In Reply to: Pro's and Con's of Martec folding prop? posted by David Allgoweer on July 17, 2003 at 22:21:29:
We have some applicable experience.
Ours is a 1990 but with a non-standard turbo version of the 4JH. Our prop was also a 18x14 while the standard according to the documentation was 18x13. The turbo only adds 10 hp (15hp peak) which I assumed was why the extra inch of pitch.
When we first got the boat it smoked quite a bit above 2200 rpm. The bottom and prop were clean as it was hauled and transported here. After a few trials I pulled the injector nozzles and had them serviced. It made a huge difference. As I recall the cost was around $25 each. We still got a little blue smoke at low speeds but I think that was due to the previous owners' running the engine too much at cold idle. This has improved the more we work the engine (it's been 3 years now)
I suspect you may have too much pitch on the prop but not by enough to cause overloading at 2000 rpm. Pull the injectors and have them serviced at a diesel service shop. Check the yellow pages and make a few calls. You could also go to your local Yanmar rep but they will no doubt send them out anyway.
Regarding the prop. You could have it re-pitched down to 12 or 13 inches. We have an 18" Martec feathering prop which we installed last year and are quite happy with it. It took a couple of tries to get the pitch right (in the water) but now can get the full 3600 rpm under load. We normally cruise at 6.8-7.0 kts with 2600 rpm in smooth water. We debated between the Martec and Max Prop and went with Martec on the basis of price. I think both are good. Others swear by the Autoprop, expecially for motor-sailing.