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Blasted engine water thru hull strainer

arf145

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Nov 4, 2010
431
Beneteau 331 Deale, MD
My Beneteau has oblong strainer-type thru-hulls for the engine water and the dripless shaft seal. These appear to be brass or bronze and do not appear to be removable. In the attached picture the engine intake is on the left.

I hate these things because they clog easily no matter how they are painted or treated, and they seem unecessary given that there's a proper strainer inside before the engine anyway.

Of course, complete replacement would be best, but that won't be happening this year. So, I'd like to cut the grill out of them. Any harm in this?
 

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Jan 4, 2006
3,822
Hunter 310 West Vancouver, B.C.
In the attached picture the engine intake is on the left.
Just out of curiosity, what is the thru hull on the RH with the grill ?

If the strainer assembly is not easily removable, cutting the grill out would be the easiest way to go. Probably easiest with a Dremel and a carbide cut off disk.

Looking at the picture of the engine intake again, is the hull penetration as big as the strainer appears or does it reduce down to a reasonable size under the strainer ?
 
Jan 22, 2008
8,050
Beneteau 323 Annapolis MD
...there's a proper strainer inside before the engine anyway.... So, I'd like to cut the grill out of them. Any harm in this?
You'd probably regret it the first time a plastic bag or seaweed got sucked up inside.
 
Oct 2, 2008
3,554
Pearson/ 530 Strafford, NH
Of course, complete replacement would be best, but that won't be happening this year. So, I'd like to cut the grill out of them. Any harm in this?
I took mine off and replaced them with the kind you can open. Now when on the hard I can clean out the little critters.

Find examples here: http://www.marinehowto.com/ Look for external strainers. If something covers the strainer (plastic balloon, weeds, etc.) you can blow back through the hose to clear it. Without a strainer you could get something lodged inside, but you could push a wooden dowel down the hose to push it out. Depends where you sail.

All U Get

Ron types faster than me!
 
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Oct 29, 2005
2,184
Hunter Marine 326 303 Singapore
You'd probably regret it the first time a plastic bag or seaweed got sucked up inside.
I agree with Ron. I had similar hull bottom strainer, caugth plastic bags, easy to remove and be on my way. Friend's boat doesn't have hull bottom strainer, caught fish in to it more than once!!
Maybe he's fishing, I don't really know but troublesome to get fish out.
 
Oct 9, 2008
1,730
Bristol 29.9 Dana Point
A temporary non-cutting-mod might me to put a switchable T or Y in a nearby thru-hull like a cockpit drain or galley drain, and have it there to connect your engine intake in an emergency should the strainer clog on the outside. This until you can change the thru-hull altogether, to a non-strainer version.
 
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Feb 10, 2004
3,491
Hunter 40.5 Warwick, RI
I had OEM combination thru-hull and external strainer like Tom the OP. Same problem- impossible to clean the critters out and I also got a fair amount of seaweed sucked into my internal strainer. So one spring I changed them. See pix below. Since then I suck in almost no grass. The round holes in the strainer cover need to be perfectly aligned with a blade of weed in order for the grass to enter. In a season, I might get 3-4 pieces of grass in my internal strainer. I generally check my strainer 1-2 per season. And these Groco strainers are separate from the thru-hull and they hinge open for easy cleaning.
 

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Jun 21, 2004
1,855
Beneteau 343 Slidell, LA
When I purchased my 343 couple years ago, I had the same configuration. The grates were covered with barnacles. I couldn't clean the inside of the strainer adequately and was concerned about more growth choking the water intake. I attempted to remove the strainer portion; however, the OEM strainer is cast as an integral part of the entire thru hull fitting. I changed out the entire thru hull to a straight fitting with no strainer. As "All You Get" mentioned, I would rather have the option of being able to pull off a hose inside the boat and clear an obstruction. Haven't had a problem with out a strainer. One thing that does concern me is that one of fittings is the water intake for the shaft and shaft seal cooling water. Without the external strainer creating some head pressure, I am not certain that water flow is sufficient. The shaft seal appears to be cool to touch when I have checked it after running, so I don't think it is a problem without the strainer. If you really are more comfortable with a strainer, just replace the OEM fitting with a separate thru hull and separate external strainer that can be removed on haul out to clean it thoroughly. By the way, when I did remove the thru hull fittings, we found that Beneteau had used some kind of brass ball valves, so I replaced those as well. Ideally, I would have liked to have installed the Groco thru hull adaptors as advocated my Mainsail; however, I didn't have time to make the necessary modifications.
 
Jun 21, 2004
1,855
Beneteau 343 Slidell, LA
Ralph,
FYI, the intake on the right is the raw water intake for the engine; the intake on the left is for shaft / shaft seal cooling water. The strainer is cast to a 3/4" thru hull fitting.
 

arf145

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Nov 4, 2010
431
Beneteau 331 Deale, MD
Actually, the one on the right in the picture is the shaft cooling water and the one on the left is the engine intake.

BigEasy, I'm the *opposite* of comfortable with having strainers on the outside! I agree with you that I'd rather be clearing any foreign matter from the strainer inside the boat than fretting about the mystery of what might be happening with water flow outside.

Replacement is the answer, but as I said, it won't be happening this year--I just don't have the time. If I do it, I'll want to replace the seacock as well. And maybe replace the Volvo shaft seal with a PSS and do away with the second hole altogether.

Ralph, my Dremel with a cutoff wheel is exactly how I imagined getting rid of the bars. Great minds, eh?

OK, so I don't go cutting into things without a lot of consideration, and I'm likely to just leave them alone for now, but any more thoughts or experience on problems in opening these things up, just in case I get Dremel-happy?
 
Jun 21, 2004
1,855
Beneteau 343 Slidell, LA
Arf,
Don't forget to check that barbed fitting where the shaft cooling water inlet attaches to the fiberglass shaft log inside the boat. I have heard of horror stories of these brass fittings corroding internally and snapping off. Checked mine last year and it looked OK. The replacements that I could find locally actually had thinner walls than the original. Beneteau no longer supplies them as far as I know.
 

arf145

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Nov 4, 2010
431
Beneteau 331 Deale, MD
Thanks BigEasy! I've heard that advice too, and I'm scared of that little sucker! Another reason, I'm thinking about the switch to PSS--I could take that off and glass over that too.
 
Jun 27, 2014
117
Jeanneau Moorings International 50 Everett
Slightly off subject, but how does that shaft cooling work anyway. I thought maybe the rear facing scoop created enough suction to suck water in through the shaft bearing. If so then replacing with a standard through hull would mean no circulation. If not then it seems like the shaft log and Volvo seal are just full of very stagnant water and the hose itself is probably full of air.
 

Apex

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Jun 19, 2013
1,034
C&C 30 Elk Rapids
read mainesails article. It looks like one of the strainers is non-directional, and the other is directional, which faces "backward" creating a scoop effect. If scooping to engine cooling, that may allow for flooding according to the article.
 

arf145

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Nov 4, 2010
431
Beneteau 331 Deale, MD
The strainer set up to "scoop" is the one for the shaft, on the right. The intake strainer on the left would not seem to be forcing water in. Seems correct to me.
 

Gunni

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Mar 16, 2010
5,937
Beneteau 411 Oceanis Annapolis
OK so I have the same OEM set up for my raw water and shaft log. Forward of that I have an open thru-hull for my A/C coolant water. Late this year the A/C system had a continuing failure mode shut down. I could not keep the system primed and pumping sea water. I attempted to ram the thru hull and backflow with hose, no luck. Finally I took the hose loose at the stainer and hooked up a shop vac in wet mode. Bingo! Opened the vac tube and there she was - a fingerling herring (shorn of dorsal fins). She was big as the thru hull and was well inside the boat.

Can't have that nonsense on my engine raw water intake...I will be keeping my thru hull strainer covers, thank you.