Rod, thanks for the input. Those are the factors I was looking for.
See my reponses below.
NormB

On Thu, 28 Oct 2004 18:37:09 -0700, "rmcinnis" wrote:


"engsol" wrote in message
.. .
Intake-strainer-exchanger-pump-exhaust

Any problems I'm overlooking with this arrangement?


Two problems.

1) Usually, the raw water pump is mounted low on the engine which keeps the
"head" that it has to prime against to a minimum. In many boats the water
pump could actually be below water line which will assure that the pump will
prime. If you have to pull the water to the top of the heat exchanger it
will mean that the pump has to be capable of drawing water several feet
higher before it primes.

Actually, the strainer and heat exchanger will be just about the same level,
(relative to the waterline) as the pump. In a Yankee 30, the engine is
mounted amidship almost in the bilge, i.e., very low. Next to the engine (outboard)
is a compartment, or box, which forms the forward dinette seat. The top of
the engine and the seat are almost exactly the same. My plan was/is to
mount the strainer and exchanger under the dinette seat, so that the hose
runs would be pretty much level. The whole works would then be about
12" above the sea water intake.

If the system has been totally drained, either from a small leak or perhaps
you removed a hose or similar maintenance item then the amount of dry
running the pump will need to do before it gets wet will increase
dramatically.

Very good point...not only would the strainer have to be filled before the pump
saw water, but the exchanger would also have to be filled as well.

2) Even once the system does prime it is likely that it will produce far
less "vacuum" then it will pressure. You might experience a drastic drop in
flow rate doing it this way.
Another good point.

Rod McInnis