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Old 08-03-2020, 06:05 PM   #1
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A little problem with my sea strainer bowl

I have been noticing a small dribble of water coming from the area of the drain plug on my generator's sea strainer whenever I shut the through hull valve while flushing the generator with shore water pressure with the boat in the lift. It did not leak while the boat was in the water. Access is restricted, and I cannot closely examine the unit. Today I connected the shore water at the tee downstream of the strainer and shut the seacock. Kapow! The photo shows the result. Apparently there was a stress crack of some sort which I finally got to show itself. New bowl on order.
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Old 08-03-2020, 06:54 PM   #2
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The strainers usual do no see high pressure but more of a vacuum that is. I would consider using a strainer that has a metal housing if you need to flush your system all the time. you are very lucky that it had happened during a water flush instead of during a cruise.
good luck,
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Old 08-03-2020, 07:40 PM   #3
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Glad you caught it. Replacing the bowl will no doubt cure the problem for many years.
Always nice to have spare strainers and bowls and o’rings for the strainers on board. Save the delay time in ordering spares.
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Old 08-03-2020, 07:40 PM   #4
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A little problem with my sea strainer bowl

Do you think that crack developed from a freeze?
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Old 08-03-2020, 08:15 PM   #5
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Yes, definitely not designed for 50 psi. While you could see pressures in the 1 to 3 psi range (each foot of water has about .5 psi) most installation are designed to have the strainer within a foot of sea level.

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Old 08-03-2020, 08:22 PM   #6
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That would sink you boat, good catch.
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Old 08-03-2020, 08:26 PM   #7
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I like your ruler very much!

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Old 08-03-2020, 10:33 PM   #8
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I can't speak to how the crack began, but the thickness of the plastic is impressive. With an alarmed bilge pump close by and the boat living in a lift when I am not running it, no real worries about it sinking the boat. Practice in the past was to leave the seacock open when flushing the genny because it was a brief time with no load which would not have given it cause to overheat. However, in recent months I have wanted to put a load on the genny while running for a half hour or more in the lift clear of the water; so I closed the seacock to ensure that too much shore water was not being lost through backflow via the through hull. I will just have to change my ways.

Yeah, the ruler came as a gift many, many years ago.
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Old 08-04-2020, 08:48 AM   #9
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That's plastic ?? Good lord I wouldn't think plastic that thick would crack like that.
Maybe the drain was tightened too tight ?? Cain't imagine...
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Old 08-04-2020, 09:44 AM   #10
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It looks like the crack originated at the drain penetration. Over tightening or no gasket or just an unfinished hole edge that allowed crack migration. Unless that is a tapered thread plug instead of a straight thread with gasket. That would be poor design.
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Old 08-04-2020, 09:56 AM   #11
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Sink a boat?

I thought all the experienced guys here profess shutting seacocks at the dock and sufficient bilge pumping capacity to handle at least one major hose failure....

Certainly have heard many chime in on those safety points.

Everyone should take heed.
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Old 08-04-2020, 09:59 AM   #12
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Both my generator and AC strainers are exactly the same type and they’re both somewhat below the waterline. I clean and check them carefully every fall but now I think I’ll be checking more often.

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Old 08-04-2020, 11:23 AM   #13
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Rich
I had a similar occurance on one of the same ones on my 34 HT.
Crack was starting from the top flange on mine. I replaced it and carry a couple spares now. I did replace the main eng bowl also as it had the beginnings of some cracks on the top flange as well.
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Old 08-04-2020, 12:36 PM   #14
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Yeah, the bowls on one of my engine strainers cracked a few years ago as well. I replaced them both and kept the intact one as a spare.

Mine didn't fail catastrophically though, just leaked. I wrapped it in rescue tape and put hose clamps around it. Got us through the trip.



Didn't think about my gen-set though.
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Old 08-04-2020, 01:18 PM   #15
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This is probably going to be obvious once I see the answers, but can engine intake strainers be located above the waterline (presuming there is available "above the waterline" space in a given engine room)?

(Obviously the seacock is going to be below the waterline.)

It's been years since I've been on a boat with an inboard and that was sailing days, so we probably paid more attention to the rigging, etc. -- and just accepted the strainers the way they were installed. Plus there's heeling to consider.

Anyway, is it possible to mount engine intake strainers above the waterline on powerboats? And if so, what are the trade-offs? (Priming? Etc?)

Thanks.
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Old 08-04-2020, 01:35 PM   #16
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Quote:
Originally Posted by psneeld View Post
Sink a boat?

I thought all the experienced guys here profess shutting seacocks at the dock and sufficient bilge pumping capacity to handle at least one major hose failure....

Certainly have heard many chime in on those safety points.

Everyone should take heed.
Remember, this particular boat lives in a lift.
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Old 08-04-2020, 01:42 PM   #17
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Quote:
Originally Posted by bayview View Post
It looks like the crack originated at the drain penetration. Over tightening or no gasket or just an unfinished hole edge that allowed crack migration. Unless that is a tapered thread plug instead of a straight thread with gasket. That would be poor design.
No, actually the crack runs just outside the cylindrical indention of the cylindrical drain. The plastic drain plug bottoms out on an o-ring in the indention. My own initial though before close examination was the same as yours, but apparently, as indicated by others here, there are issues with cracks developing in this brand of strainer bowls in various places, and not all were pressure stressed as mine was.
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Old 08-04-2020, 02:03 PM   #18
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Quote:
Originally Posted by Frosty View Post
This is probably going to be obvious once I see the answers, but can engine intake strainers be located above the waterline (presuming there is available "above the waterline" space in a given engine room)?

(Obviously the seacock is going to be below the waterline.)

It's been years since I've been on a boat with an inboard and that was sailing days, so we probably paid more attention to the rigging, etc. -- and just accepted the strainers the way they were installed. Plus there's heeling to consider.

Anyway, is it possible to mount engine intake strainers above the waterline on powerboats? And if so, what are the trade-offs? (Priming? Etc?)

Thanks.
Yes you can definitely locate the strainer about the waterline. My generator installation was done that way. Don't know if it was by design. Most modern diesel owner/installation manuals will give you a suction spec in inches, that they will self prime to. If I were going to do it, I would have the bottom of the bowl a couple of inches above the water line at most.

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Old 08-04-2020, 02:08 PM   #19
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Rich, I had something very similar happened to my strainers as well. What I think happened was that I did not seat the metal strainer properly into the bottom slot and I tightened the cap down. That is the only thing that I can think of that would have caused it.
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Old 08-10-2020, 08:26 PM   #20
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Originally Posted by kwmeyer13 View Post
Rich, I had something very similar happened to my strainers as well. What I think happened was that I did not seat the metal strainer properly into the bottom slot and I tightened the cap down. That is the only thing that I can think of that would have caused it.
You are more correct than you know. As I was fastening the new bowl onto the upper portion of the strainer I did so with the strainer in place and the cap fully screwed down. I wanted to see if there was interference, and sure enough there was a gap as the six cap screws began to tighten. The stainless steel bale of the strainer basket exerts a lot of pressure on the bottom of the plastic bowl in normal tightening of the cap down to full metal on metal contact. So I cut the bale in two so that the two pieces can overlap acting as leaf springs as the cap is tightened. MUCH better. Anyway, I am back in bidness and five pounds lighter for having to squeeze down there in the tiny space available in BUZILLION percent humidity and surface of the sun heat today. The anchor windlass solenoid replacement will be a snap sitting up there on the bow in the shaded sea breeze....
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