You were lucky. The general guideline from the mechanics I know is that
it takes 30 seconds to start to destroy an impeller when run dry. There
are some impellers made from fancier materials that suposedly can
be run dry for a while, but they cost 3x or so more. I also suspect that
a new impeller can survive longer. I replace my impeller every
spring as part of my normal recommissioning to try to avoid any sort of
impeller failure. I also open the seacock once in the spring and then never
close it until fall unless I am leaving the boat unattended for a long
period
of time. So starting the engine with the seacock closes is not likely.

Doug
s/v CAllista

"Dave" wrote in message
...
On Fri, 17 Dec 2004 17:54:02 -0500, "Doug Dotson"
said:

The impeller will self-destruct way before any temperature alarm
sounds.

Not my experience, at least on my Yanmar. Had the engine heat up enough to
shut itself down once this summer before I noticed the temp light. Pulled
the impeller this fall--no damage.

There is no substitute for good
procedures that are followed.

So true. In this case I carefully followed my checklist on day 1, but
forgot
on day 2 that I had closed the sea cock the previous night.