Hello, all. This will likely be the last post as I finally resolved the white smoke issue. To recap, I was blowing stinky, diesel smelling white smoke. My engine has 600 hours, and there were no indications that I was losing coolant (i.e., not a head gasket issue). The smoke became progressively worse as the RPM increased.
1) I had my injectors serviced--one nozzle was particularly filthy. The result was a significant reduction in white smoke at start-up and no sheen in the water as well. I also saw a HUGE reduction in the white smoke while underway.
2) I still had a very small amount of white smoke at higher RPMs, and my temp seemed much higher than normal but no overheating. Well, it was a little steam. I did remove my cabin heater before the injector servicing, which resulted in a higher operating temp. The engine's raw water pick up has a 5/8" barb. The hose then went to a 3/4" hose via an adapter. I suspected there was not enough water flow as the engine was designed for 3/4". I replaced the barb with a full-flow 1/2 NPT to 3/4" barb and ran a new length of 3/4" hose to the strainer. The engine ran slightly cooler, and I no longer observed the small amount of steam.
It, therefore, appears that I had two issues. I will be hauling the boat out in the winter to replace the current raw water strainer/through hull and valve arrangement. It appears that the current valve is too small (1/2" NPT to 3/4" barb). I will replace the through hull with a larger 3/4" scoop and a 3/4" flanged valve. I've owned the boat for several years, but perhaps the cabin heater was masking the water flow issue and allowing the engine to run cooler with the reduced flow.
“Go small, go simple, go now”
― Larry Pardey, Cruising in Seraffyn