Glenn,

There are a few things you can do to reduce diesel shake.

First, if your engine has more than 500 hrs on it, it is probably time to adjust the valves. As the engine wears in, the valves seat farther into the head, reducing the clearance between the rocker and the valve stem, Ultimately it affects the valve timing and the roughness of the idle.

Second, an after-market Cetane booster will help. As the diesel full sits in your tank week after week the more volatile components boil off, dropping the Cetane rating of the fuel. Adding a Cetane booster at the beginning of the season and mid season will significantly improve the idle performance.

Finally, sometimes the idle speed of the engine just excites one of the resonant modes of the hull, and the boat seems like it is shaking itself to pieces. bumping up the idle speed by 100 -200 rpm will take it out of that resonant mode and significantly reduce the shake.

If none of those work, some folks buy a Honda 2000 generator and put it on the swim platform, and use that to charge the battery. Then the diesel doesn't shake at all :)

Dave