On Wed, 07 Nov 2007 01:50:41 GMT, Jere Lull wrote:

We've found that even with the fresh water closed off, we have about 5
minutes' run-time at cruise power (about 2200 rpm) before the high-temp
alarm sounds -- quite a bit further than 200 meters. We used that
reserve once about a decade ago, so I know it exists.

I am not sure I would rely on the light to protect the engine. I know
that it is supposed to...

What do you mean by fresh water. My [22 ft sterndrive] is cooled by
glycol and has a heat exchanger. If I am floating in salt water, there
is no fresh water involved anywhere.

I have heard the heat exchanger/glycol arrangement refered to as fresh
water cooling. There is seldom [never?] a shutoff in the coolant
lines, although there is generally a seacock in the raw water line.
When was the last time you saw a shutoff in a car cooling system?
One thing is certain, unless the pump is managing to circulate coolant
through the engine, it won't last anything like five minutes. The
difference between driving with a broken fan belt, and driving with no
coolant. That will warp the head[s] almost immediately. You got away
with it once, so appearantly the light gives sufficient warning. I
like a gauge. That shows up a problem sooner than a light. My car has
both gauge and light for the oil pressure.

Casady