Raw water valve control

[downeast450]

Our Islander 28 has a fw heat exchanger. This allows some time before I need to open the rw thru hull after starting as all A-4 operators should do. That is a good thing! Getting to the valve to open the rw intake is not fun. All thru hulls get closed before leaving the boat so this is an exercise that is part of any day aboard. This year I replaced the rw thru hull valve and positioned it to allow a cable with a clevis end to push it open and pull it closed. Wonderful! Now, upon starting, I can just push on a "T" handle mounted just inside the cockpit's port hatch, rw starts to flow and the wl muffler starts doing its job. To shut this down I pull the "T" back up to seat the valve closed. The throw of the cable control opens the thru hull valve about 90% when fully down. It closes it solidly when pulled up. The water flow is adequate since the large strainer we have churns and is always full. The volume of water coming out of the exhaust is normal. I am enjoying being able to control this from the cockpit now.

http://s598.photobucket.com/albums/t...Islander%2028/

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[RichH]

The Oberdorfer raw water pump 'does not' like to run dry and can quickly abrade the cam lobe, etc. Typically the Oberdorfer types will 'drain back' (by side seal leakage) through the intake valve when the engine is shut down, until the valve is closed. So, keep an eye on the Oberdorfer impeller vanes, etc. if you do this 'dry' running at start-up to verify that you arent causing adverse wear in the pump/impeller.

[downeast450]

Rich,

You are right.

That used to be a concern. With a large strainer full and the T handle right next to me I have the seacock open immediately. There used to be a delay as I crawled down to open the valve by hand.

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[tommays]

I understand why you made a hard to reach handle easy to move.

BUT my A4 has never needed more than 5 seconds to start ?

[downeast450]

Mine starts immediately, too. It is good practice with an A-4 to wait until it does to open the rw seacock.

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[tommays]

why ?

it is hard on the pump inpeller to run dry

[downeast450]

The advice I get from Moyer Marine is to wait because if someone doesn't understand the way a wl muffler might back water up into the exhaust manifold if there is a prolonged delay in the engine firing it could damage the engine. If the engine does not start and the operator continues to turn it over with the battery it fills the wl muffler with cooling water being pumped by the engine's starter motor turning the water pump. If the water level reaches the height of the hot pipe's turn down to the muffler it will flow back into the engine. Running down a battery with a hard starting A-4 is a recipe for disaster. The real solution is to keep it running well. I do as do you. In any event, I have to open the rw valve either just before starting my engine or just after it starts. Since I have a wet impeller anyway and now have a handy way of opening the valve without crawling down into the engine space, I wait. I used to have to crawl down and shut it before leaving the boat. Not any more! Yippee! That is just my personal rule with all thru hulls.

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[Barquito]

I guess in a perfect world, all throughulls would be in a place that is accessable enough to encourage regular usage. That just isn't possible on all boats.