Through hull...

dmunneke

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exMember
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May 1, 2007
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26102
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So the two kinds of through hulls I see have external slats or holes to keep out the big stuff.. Where I boat these slats are getting clogged with algea etc.. Is there a reason for these with a sea strainer not 12 inches away. Couldnt it be an open hole ? Any experiance ?
 
If you have a strainer in line, there is no need for a through hull fitting with slats/screen/strainer. Next haul out use a grinder to cut out the slats.
 
I had a 26" Penn Yann that would collect alot of eel grass because of the position of the intake. I put one of these on each one and had alot less problems. On Long Island it's called a south bay strainer. I don't know what the real name is, but it's an oversized sea strainer that fits over your existing one.

Oversizedseastrainer.jpg


Hope this helps.

Billy K.
 
Usually when the outside strainers have problems, they are coated in paint, narrowing the slits. Solution is to scrape/scrub them clean. You would be surprised how much crud these things keep out of your strainer. I'd try to troubleshoot it before removing it. Otherwise, theoretically you will simply be cleaning out your inside strainer frequently.

I had a strainer we were catching kelp daily and threatening to over heat the engine. The cure was a good cleaning of the slits. As they narrow, physics tell us that the pressure & flow is greater, thus things stick instead of passing by. After a thorough cleaning you could run over a kelp patch and not catch anything.
 
these south bay strainers work. I know people who've installed them on main engine intakes (big diesels) and they're very happy. I installed one last year on a watermaker intake and it's working very well. no more cleaning grass out of the strainer every couple of hours!

next haul out, they're going on all air cons and gensets.
 
If you keep the outside strainer as some have suggested, pipe your compressed air source into your raw water intake so you can use the air to blow out your external strainer to clear it. No compressed air source? Teach the old lady or one of the kids how to dive over the side and clear the strainer. Not an option? Cut the slats off and clean the in line strainer as needed.
 
L. Keith.. I tend to be with you.. I can clear my strainer as needed.. but not as easy to go over the side with a wire brush when I get home from work after dark and its freaking 98 degreees
 
The external strainers over the scoop intake cause probably 99.9% of eel grass and other small flotsam to slide right past as water is sucked in when cruising. The seacock strainers would clog up quickly around here with out them, but my basket strainers usually only get a few blades of grass a year . I sure think it's worth it to go under on rare occasion and clear the slats on mine by simple raking with a small flat-blade screwdriver. But I do rather wish I had the south bay strainer or even the slotted type with an external strainer plate that can be temporarily uscrewed & removed for best cleaning and especially for access to clean barnacles from the actual thru-hull or paint inside there. I just raked excess bottom paint and a bunch of calcium buildup from those external strainers a week ago and it made a slight difference in dash temp. Air wouldn't have removed that material.
 
Anyone have a good source for these strainers?
Thinking it might help with the zebra mussel problem we have on Texoma.
I might try one next year.
 
dmunneke,
I have struggled for a couple of years with my air conditioner intake. Originally I had this as a thru-hull
strainer4.jpg

And like you a foot or so away I had a strainer…one of these
strainer3.jpg

With this setup I was always sucking up grass, minnows, sticks etc. The smaller stuff like the grass would go into the strainer but bigger stuff would stop at the elbow before the strainer. Toward the end of last year the seal on the strainer was sticking and it was a bear to get apart to clean. Also with this setup I would lose prime if I didn’t shut the ball valve before traveling.

So this spring I popped out the thru-hull and put in one of these
strainer.jpg

And replaced the plastic strainer with one of these
strainer2.jpg


Well this year the prime issues are gone but the problems continue with stuff that is plugging up the slots on the thru-hull and very little is getting into the strainer. I don’t know which way is worse. The south bay strainers look interesting but me diving the boat to clean them is going to happen.

I stern in to my dock which puts this intake closer to the bulk head and around more weeds and crap floating in the water. I have been thinking about bowing in.

July for us is also the time when those dead algae globs are floating around and may be a lot of my problems.

Don’t know what to do but it sure is a pain

Niles
 
Niles,
I have pretty much the setup you have gone to now.. What a pain.. Maybe the monster strainer is the answer.. I see they have one ten inches... That should take a while to plug.. I could see the problem of stuff getting caught in the hose.. that would be a pain to take off all the time. looks like no easy solution will be forth coming... I going to cut the slats out.. Let her flow. the strainer will plug.. but thats a 2 minute fix for me and back in business. I might even plumb a y and put two..
 
I don't understand the use of the external "south bay strainer" on any inlet that may be used while the boat is stationary for any length of time, especially an air conditioner or generator. On engines, I do get it, as the water rushing by wipes them off. But otherwise, I see them causing more hassle than solving it. What am I missing?
 
With my AC water pick up, I was having big problems sucking stinging nettles up into my water line and clogging up the works. During my winter haul out, I had a strainer installed over the thru hull opening.
 
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