Sandy and All,
I'd like to thank everyone for their comments. I sort of figured that
excess heat and getting cool air to a radiator would be a hindrance. I
definitely think a closed system is the way to go even in fresh water,
though I probably wouldn't pass on a boat with regular open cooling system
since I do boat in fresh water. In salt water I'd only buy a closed system.
Paul

wrote in message
...
On Sun, 25 Apr 2004 15:57:13 -0400, "Paul Schilter"
paulschilter@comcast,dot,net wrote:

Since external water used in cooling engines causes a lot of problems,
why
hasn't a car type radiator system with fan ever been used?
Paul


In layman's terms, an inboard engine in a planing hull works very hard (as
compared to a automobile engine) because the inboard engine is always in
the
automotive equivalent of first gear. The water in a radiator is hot,
whereas the raw water (from a lake, river or ocean) used for cooling an
inboard engine is at the very most less than half as hot as radiator
coolant, and most of the time the raw water is around one-third the temp
it
would be if it were radiator coolant, so an inboard engine must run cooler
with raw water than the same engine would run if it had a radiator.

A fan and radiator on the end of the engine would take up extra room,
about
1 foot or so, in a small inboard runabout, room which really is not
available.

Also, a mechanically driven fan which cools a radiator takes some
horsepower
from an engine. An inboard engine does not lose this small amount of its
horsepower.