OK, Radiators, heat exchangers, air to fluid, fluid to fluid, air to air,
blah, blah blah. They all get rid of heat or absorb it, whatever - there's
a transfer of heat from something "hot" to something less hot. or vice
versa.

The original question was really asking why are there not car type
"radiators" on boats. This semantical stuff, while interesting (NOT), is
irrelevant, imho.

Has anyone yet pointed out that it simply works better to exchange motor
heat with an unlimited supply of cool liquid rather than air? Cars first
take the heat from the block with liquid for this very reason. Air cooled
engines are generally very small in comparison.

In a car, however, the liquid is limited because it's a closed system and
therefore the next step is to transfer to the only unlimited cool thing
around, the air.

Boats goe through an unlimited supply of cool liquid which is better at
taking away the heat than an air-based "radiator". Therefore, the use of a
small fluid-fluid heat exchanger rather than a large fluid-air heat
exchanger. Some bypass this also with lake or ocean water cooling through
the block w/o exchanger.

Air boats, being the main exception to this use car type heat exchangers,
aka "radiators" because (1) they *can* (space and air movement allows them)
and (2) they don't have an outboard or outdrive leg, or jet intake to
easily suck in the water. Sure they could have a water inlet like a
straight inboard, but because of (1) above, they don't have to.

Just mho,

Cam