Raw Water Slotted Strainer - Which Direction?

[Paul Akers]

Because I had a problem in recent seasons sucking up debris that clogs my intake or raw water strainer (this basically happens when stationary and charging batteries), I've decided to mount a slotted scoop water strainer on the hull of my Legend 37. It's the type that has the thru-hull intrgrated as part of the slotted scoop strainer. http://www.yanmarhelp.com/i_rawwtr.htm suggests mounting the slotted scoop facing AFT since it reduces the possibility of picking up stray material that could clog the strainer. So, I'm inclined to mount it facing AFT. But as I walk around the marina, I find them on boats facing both fore and aft. Some sailboats have two (maybe a generator) and they sometimes have them facing both directions. In your experience, which is the proper direction to mount the slotted scoop strainer?

 

[Rich Stidger]

I wouldn't mount one at all because....

If you get a clog with one of these, I think it would be VERY hard to clear without diving.Also, I have one on my AC intake and I have some problems with marine growth inside. It is extremely hard to clean it out. Equally hard to get any bottom paint inside to ward off the critters.In answer to your question as to which way to mount, I think that facing aft would be preferable. The reason is that it would be less likely to "scoop" junk into the openings and at sailboat speeds there should not be any issue of being able to pull water into it while moving.Facing forward would tend to scoop in water and make it easier on the pump, but IMHO it is not a significent factor.

 

[Ed Schenck]

Here's the scoop.

This was discussed recently but I think the archives may be unavailable. My own H37C faced forward from the factory. I am installing a new larger one with seacock. It will be installed facing aft. The argument was resolved by some website that suggested forward for boats motoring at some higher speed, 15 knots or more I think. For sailboats under 10 knots the recommendation was to face it aft. I am hopeful that aft-facing will eliminate some clogging issues. You might do a Google search, I bet you find that website.

 

[J. Tesoriero]

Face Aft!

I agree with Ed. There was a discussion a month or so on this topic and the final vote was heavily in favor of the aft facing slotted scoop strainer. I changed mine to an aft facing scoop some time ago and have not had a clog in several years (knock on wood). I find that if I cannot avoid a dense patch of eel grass when motoring in a narrow ICW channel, I can throttle back and glide through the patch and continue with no clogging or grass in my raw water strainer at the end of the day. It is unlikely that your boat could go fast enough, but there is always the possiblity that a forward facing scoop could push excess water into your engine when under sail.

 

[Fred Ficarra]

AND another strainer that works is

those little bowl shaped sieves that you just attach to your hull with screws. I've got two. Haven't had a clog in 15 years. Nothing grows inside and I don't know why.

 

[Tom S]

Rich, then you need to get a removable cover

Like I added. Pin holds it in place and swivels open to paint or clean inside. I like it Like the onehttp://www.groco.net/images/strainers/strainers-RSC.htmlThough they also make ones that are beveled that open either with screws http://www.groco.net/images/strainers/strainers-SC.htmlor a swivel hatch http://www.groco.net/images/strainers/strainers-APHS.html(I went for the smallet lowest profile that would still allow water flow - too small and it will restrict intake -- in fact I even drilled a few holes larger just in case)My take for sailboats it really doesn't matter, with that said I would put thiner pointy end forward to reduce drag. On a motor boat at high speed, it might also scoop up too much water forcing (?) water up into the engine raw water intake....hmm maybe thats a good thing?

 

[Paul Akers]

If it did clog...

...I have an alternate plan to get me back to the marina. My head intake seacock is located adjacent to the raw water intake. Fortunately, I'd be able to switch them off and use the head intake as a "backup".

 

[Rich Stidger]

Tom, very interesting...

I didn't know that anyone made covers like these.The one that I have is my AC inlet and it is half-way down the hollow keel. It was made as one piece with the slotted cover and base attached to the threaded pipe that forms the thru-hull. In order to replace it, I need to remove the entire thru-hull, not just the outside slotted cover.It is a lousy design IMO. It was also a Hunter factory original!