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Maybe I overstated the problem. There isn't any visable black exhaust smoke. The soot on the transom is the result of an entire summers worth of activity including one 24 hour stretch when we motored back from Maine. It's just that last year the transom was clean when I hauled and this year I had soot all over the transom.
Did you notice much of a change in the boats response at lower RPM's / speed after you repitched the prop? As far as 3500 RPM's I'm with you...I don't think I could do it.
I have some other questions concerning my CD-36 that I would like to run by other owners. Would you mind?
Mike
matt cawthorne wrote: Mike,
Do you actually see black smoke during operation? If so, what rpm does it appear at?
The rpm numbers sound familiar. Prior to my re-pitching the prop the boat reached 7.0 knots at 2500 rpm. The engine maxed out at 2600 rpm with black smoke. When I re-pitched it to a 12 pitch the boat was able to make 7.5 knots at 2980 rpm. I calibrated the tachometer for these measurements, but simply used the boats knotmeter for the speed. Somewhere I have a sheet that lists the maximum cruising rpm for the 4.108m at 4000 rpm. I would have to be in fear of loosing my boat or my life to run the engine above 3500. I could not bring myself to take it above that while calibrating the tach.
Next season try dropping the charging current using your smart regulator. If that does not fix it then it is not your alternator.
Mike,
All questions welcome. Web page or e-mail are both fine. You should always use the search function first, as many questions have already been answered.
As for the soot.... Some years I get it on the transom and some years I don't. The worst year was when I went to Bermuda the last time. I put a flapper valve over the exhaust that year because of the offshore sailing. The whole trip out was downwind. Each day I would run the engine to charge the batteries. By the time I got there the transom looked bad. The exhaust was getting blown/washed back at the boat the whole time. I was real glad for the flapper though. The best year was the year that I put 20% biodiesel in the tank. The transom looked perfect at the end of that season. Most seasons it is minor.
I will post the info when I get it. I need to go do an RPM vs. speed trial so Michigan Wheel can get an idea of what she will do as currently configured. That probably won't happen before the 20th, so don't hold your breath.
Keep on sailing, it's only October!
Ken
Jerry Kimble wrote: Ken, please post the info. you get from Michigan Wheel.