Raw Water Strainer Height - Perkins 4.108

[CharmCityBoater]

I want to relocate the raw water strainer for my perkins 4.108 to a location inside of my lazarette on my Tayana 37. The location is above the highest point on the engine by 1 foot. Of course my concern is two fold:

1. Is this too high for the salt water pump to pull water through?
2. Will this cause any other issues? Siphoning? Water backfilling engine?

The current location is so low in the bilge and so hard to get to that I never want to check the condition of the raw water strainer as I need to be a contortionist. I need to relocate it but need to know the parameters I should be following.

Thanks

Phil
Tayana 37 Hull #450

[a64pilot]

I would keep it low, reason is if it has just a tiny leak, it will suck air as opposed to water, plus if you open it to clean it, it will let in a large amount of air that the impeller will have to suck out before it gets water, making it run dry for some time, and it may be enough to damage the impeller.

[Lepke]

Ideally the plumbing from the seacock to the pump always rises so air pockets don't form.

[rbk]

Phil,
Same engine same boat; I relocated and installed a new Groco strainer. Before I would have to crawl into the aft locker, open back access engine hatch from lift floor plate, shut off thru hull and unscrew top of strainer under the bulkhead while hoping not to drop parts into the bilge under the engine (if you have the same setup I’m sure you’re aware) I’ll have to see if I have any pics tomorrow of the install but is a thousand times better. It can all be accessed from the quarter berth locker access panel (while lying in the berth) or crawl into the locker from the cockpit with no chance of dropping parts. Leave it low as the pumps may not be able to prime if you run dry or is air locked.

[El Pinguino]

Vetus reckon the strainer should be 15cm/6 inches above the waterline which will mean it is above the level of the water pump.

Better air getting into one above the waterline than water getting out of one below the water line......

https://images.jamestowndistributors...e/11783(2).jpg

[CharmCityBoater]

Rbk,

That is the exact feedback I was looking for. Yes, mine is behind the access panel in the lazarrette under the cockpit. Pain in the neck. I was going to install it in the lazarrette on the wall where the quarter berth is.

Would love to see your picture.

Phil

[rbk]

Are you going with a Groco? They’re bigger than they look but worth it. Location also depends on your intake thru hull location. If it’s down next to the shaft where mine is, the location and bends required limit you severely without running hose all over. I had to make a cut in the floor panel but it more or less keeps the area clear while providing excellent access.

[CharmCityBoater]

Yes, going with a Groco with 1” inlets. Yes, my thru-hull very close to the shaft seal. Will be putting in a new thru-hull in same place as original so I can figure out best direction. Where exactly is yours and how is your hose ran?

[rbk]

Ok so no pictures that I can find but I am sure I took one at some point. If you're sitting in the back locker facing forward/engine, the strainer is now located on the SB corner, floor level against the engine bulkhead, tucked into the corner. Hose comes from thru hull/seacock - 45' elbow up through floor (could not go with a straight fitting due to floor stringer and bend for hose) to 90' downward facing elbow on strainer. Following flow towards engine is another 90' elbow off the strainer facing forward, through bulkhead to raw water pump. I will be heading down next weekend to install new alternator I can take pictures then. You should plan on installing any new thru hulls before mounting new strainer as I found the new Groco thruhull/seacocks are higher/taller/bigger than the original GD Tayang installed. Also check your thru hull diameter and raw water pump dia as mine were different and had to move to a full flow elbow off the strainer.

[mikecambrai]

With my Vetus strainers, I sited them such that the water level from outside was 1 inch above the bottom of the strainer. Thus when I took out the strainer filter to clean it there was water within the casing but it did not overflow. Then when I put the filter back in and started the engine there was water feeding the pump. It then would draw some air and water through the system until there was only water in the strainer visible from the transparent top.

[Squanderbucks]

It doesn’t matter that much about where the strainer is. The raw water pump will simply prime it and fill it up in a few seconds.
It would only matter what the height of the strainer is above the thru hull for purposes of self filling purposes. if both are below the Waterline it may self prime. Often they are not and require priming. If the pump cacicty is so slow to take a long time to fill it then it should be primed.
With the thru hull fitting below the waterline the engine pump will pull water up and through the higher mounted strainer.
If desired the strainer can be filled or partially so if it does not fill on its own. Most flexible impeller raw water pumps will run dry 30-40 seconds with little problem. Globe impellers run longer.
Once primed the first time there should be no worries. If you are worried about an air leak being a problem - fix it so there is not one.
Also look at the spec for the pump they should tell you what the maximum head height is for that pump. Many are 8 to 10 feet.

[KP44]

I would want the strainer location to be above waterline and nearly center athwartship. That is; near center of the beam. Even healed-over it is never below waterline.

[rbk]

I went down, installed new balamar system and fired engine for first time after too wnd rebuild but totally forgot to snap a pic of the raw water strainer installed. I will be back down again in the near future of you can wait for installed pics?

[CharmCityBoater]

I can wait

[fish53]

I have mine higher than both the seacock and pump inlet making it the highest point, as it's all at or below the waterline there is no air and it doesn't dump water in the bilge when I clean the strainer, just close the seacock first.