fresh water intake filter question

[Boaterguy]

I am looking at installing a filter on the cooling intake line. It has a clear removable lid, neoprene gasket, input and output lines. Should I install it above or below the water line? Does anyone have one of these, and can you make recommendations as to how it should be installed.

Thanks

[Rodman]

I have one, It sits right in front of the motor, Has check value so I can take water in through a hose or fresh water. Ill see if I can get a pic in the morning and post it.

[Danny Bailey]

I have one on my genny and it's above the water line

[captainmaniac]

I have two strainers - one for the Genny, the other for the A/C. Both of mine are below the waterline (plastic 'sight jars' with metal element filter inside).

Above the water line allows you to crack the strainer open to replace the filter element or clean it out, without having to worry about closing seacocks etc. Also if the strainer itself ever breaks, you are not likely to sink. Install it below the water line, and you will last as long as your batteries can run the bilge pump... Reminds me of a guy years ago who was doing some engine work and disconnected his exhaust hoses from the risers, but propped them up on top of something to keep them above the water line (since his exhaust outlets were under water). Unfortunately one of the hoses shifted through the night and fell to the bottom of the bilge... by morning there wasn't much boat visible anymore. Oh well -- live and learn!

The down side of mounting it high is the possible need to prime the system if you ever do open / drain it. The less air the engine water pump has to suck before it gets water, the easier you will be on the impeller.

By the way - I see your signature - do you keep the boat in NOTL?

[Paul]

If you're installing a filter in a line for a "static type" pump, like the pumps used for marine engine cooling, you can install it above the waterline. These pumps create enough draw or suction to self prime the system. A "dynamic type" pump, such as an A/C pump, requires a flooded suction and would therefore have the filter installed below the waterline.

[rossjo]

My strainers are all below the water line, but the seawater pump is slightly above the water line.

I don't have strainers on my 26/Mercruiser, but have considered it ... I did change from drawing water from the Bravo-1 outdrive to a bronze scupper in the hull, with a large brass seacock (with stainless handle).

I plan to add "crash pump" plumbing to both boats this year (along with about 1,000 other projects).

[Danny Bailey]

I have one on my A/C water supply too. Its solid bronze and below the water line (would have to be, that pump is a centrifugal and is not self priming)

[Paul]

Boaterguy,

Just curious. Why do you want a strainer on the water intake for your main engine? Have you had weeds or somthing else get past the scoop type strainer under the hull and clog up your trans cooler or pump? Since the boat is in motion for most of the time that water is drawn thru this intake, isn't there less chance of something getting sucked up? Thats how I see it in waters that we boat in. Things may be different where you boat, and by the way I think your fortunate to be boating in such a beautiful area of the Great Lakes.

As far as the A/C and generator intakes are concerned, I have a strainer on both since these are used when the boat is at anchor or in a marina where weeds are more likely to get sucked up.

[Boaterguy]

Captainmaniac- I have a slip at the mouth of the Niagara River. A great spot.

Paul- I guess I want the piece of mind that the filter will catch any stuff that might go through the system. When I replaced the impeller in my pump I noticed that one of the fins had a tear in it- I assumed that something got into the intake and went through the pump. I would like to catch anything before it makes it to the pump. I have been into a few marinas that have heavy weed growth and don't want to run the risk.

[ready123]

That tear could just be usage.... how long had the impeller been used?
I think your plan is overkill for the clean lake waters we have here!

[rossjo]

Ye s- the impellers tera on their own over time. Good to replace them annually - but most people don't - bi-annuals is minimum.

I have an odd routine - I check for water flow out of each exhaust when I start each engine. I caught a bad impeller on my port engine 3 weeks ago and changed it before we set off for 4 days. Saved me much heartache. I only had a slight increase in my normal engine temps which led me to check. The impellers blades were breaking down badly.

[gettaway]

It is hard to believe there is not a strainer on the intake of your cooling system.

It is worth the protection to your pump, heat exchangers and exhaust.
It is probably a good idea to operate seacocks anyways.