R.P.: The Sherwood pump is covered in an earlier post.
http://www.trawlerforum.com/forums/s...umps-7235.html
I hope that link leads you to the correct post. (techno-klutz here, fingers crossed that it works.)
Someone mentioned keel cooling, which I've done before. The trouble is that unless you have an unusual trawler, it's challenging to convert to a dry exhaust. So, if you stay with a wet exhaust, you still need a sea water pump, etc. What is entirely feasible is to convert an engine to a conventional exhaust manifold and thermostat housing, such as would be used on a truck or generator, and mount an external heat exchanger somewhere in the engine bay and connect it to the engine with radiator hoses. I did this on a 120 HP Isuzu industrial engine and it works fine. We used a coolant expansion tank from a 3208 Caterpillar generator set, and wrapped the exhaust manifold and turbocharger with insulation, and the thing works very well.
The boat owner has an uber-dependable engine, the below deck exhaust temps are lower than with his old Lehman, and it doesn't leak a drop. Someday I'll get pictures and post them.
Onward!
JS