Cooling water failure lesson

Thread view:

Enable EMail Alerts

Start New Thread

Thread rating:

Roger Long - 26 Mar 2006 20:39 GMT

Here's something about cooling water intakes I learned the hard way
last year even though, somewhere in the recesses of my mind, I'm sure
I knew
better at the time.

Http://Home.maine.rr.com/rlma/Strider0603.htm#cooling

BTW there was quite a bit of discussion here about the Aqualarm when I
was putting it in last year. My conclusion after a season of sailing
is that it functions well as an alert to total stoppage but isn't much
good, at least with small engines, at alerting you to reductions in
flow. Ironically, my only cooling water system failure was caused by
the alarm installation itself. At least it told me though:)

Now that it's properly set up (or will be tomorrow) , I'm glad to have
it on my boat.

Signature

Roger Long

Reply to this Message

Larry - 26 Mar 2006 22:01 GMT

"Roger Long" <rwlong@maine.rr.com> wrote in news:N5CVf.17410$Da7.4368
@twister.nyroc.rr.com:

> Http://Home.maine.rr.com/rlma/Strider0603.htm#cooling

Had priming problems after sailing in an air conditioner system on a
friend's boat. He was always disassembling the damned thing to get it to
reprime after sailing each time.

Screw that. I tore it apart on a Saturday and moved the pump and strainer
down to the seacock end, about 3" from it, so it would always have good
positive filling from the pressure as soon as the water got in the boat.
AFTER the pump, it never is a problem. The pump will blow the hell out of
any bubbles right through the heat exchanger. If the strainer isn't just
plugged full of prehistoric, uncatalogged marine life, a common condition
at any marina in Charleston, it'll prime, every time after heeling over. A
simple valve on the outlet of the pump left open ended, lets me bleed the
strainer full after cleaning it out, too. That also primes the pump easily
after the strainer was cleaned....about every 2 weeks in Summer. Docks
just breed the nastiest little centipede-looking biting animals I ever
saw....

Wear gloves....

Reply to this Message

Roger Long - 26 Mar 2006 23:02 GMT

It would be quite a job to relocate the raw water pump on my Yanmar
much lower:)

I thought about running a line from after the pump over to the
Aqualarm and back for just the reasons you cite but am reluctant to
change a silver painted factory hose. No practical reason not to but
it's the kind of thing that could be a hang up and haggling point with
an unimaginitive insurance surveyor down the road.

Signature

Roger Long

Reply to this Message

Steve Lusardi - 28 Mar 2006 08:03 GMT

Roger, the lesson you learned is wrong if you think the strainer should be
below the water line. You immediately lose the ability to clear blockages
through the hull fitting. if you do. Any decent rubber impeller pump will
suck 2 meters of head if the tips are kept wet by a post pump riser.
Steve

> Here's something about cooling water intakes I learned the hard way
> last year even though, somewhere in the recesses of my mind, I'm sure I
[quoted text clipped - 12 lines]
> Now that it's properly set up (or will be tomorrow) , I'm glad to have it
> on my boat.

Reply to this Message

Roger Long - 28 Mar 2006 11:30 GMT

I didn't mean to imply that as a hard fast rule. Everything is very
close coupled on my boat. It was the fact of the airlock being very
close to the pump so that the piping was still airbound when the pump
started cavitating in air.

Yes, the pump should be able to lift that far but you want an engine
cooling system to still function event when the pump impeller is
compromised by wear or air. Make everything as easy as possible for
it.

It's possible that I could have gotten the flow restored by going up
to maximum RPM for a while but I started assuming blockage or impeller
failure. It was a pretty exciting day and the implications of the big
heel angles didn't sink in till later. The suction is pretty low.

My seacock is right next to the strainer so I don't lose anything by
keeping it all self priming and easy flowing. If your strainer has to
be far from the seacock, then, by all means put it above the
waterline. Just don't have it right next to the engine with a short
hose running down from the strainer to the pump.

Signature

Roger Long

> Roger, the lesson you learned is wrong if you think the strainer
> should be below the water line. You immediately lose the ability to
[quoted text clipped - 20 lines]
>> Now that it's properly set up (or will be tomorrow) , I'm glad to
>> have it on my boat.

Reply to this Message

Roger Long - 28 Mar 2006 12:56 GMT

You should also consider that, if your cooling system is blocked or
sucks air, your pump impeller will be quickly damaged. It may be
capable of keeping your engine running but not tight enough to
provide much suction lift spinning mostly in air. The more you try to
get it working, the worse it's going to get.

Signature

Roger Long

>I didn't mean to imply that as a hard fast rule. Everything is very
>close coupled on my boat. It was the fact of the airlock being very
[quoted text clipped - 43 lines]
>>> Now that it's properly set up (or will be tomorrow) , I'm glad to
>>> have it on my boat.

Reply to this Message

Boat Forum / Cruising / March 2006

Cooling water failure lesson