Raw Water Strainer Failure - Endemic?

[Bay Pelican]

The bolt holding down the lid of my raw water strainer for my genset fell apart last night. This opened the lid of the strainer just enough that water poured out. Fortunately the flow was constant but not overwhelming and the bilge pump handled the water until I noticed the problem. Closing the thru-hull, switching the generator to another strainer and plugging the hose from the thru-hull solved the problem for now.

The generator was not in operation when the failure occurred. We were at anchor at the time.

The strainer is 32 years old, likely a Perko, and is one of several identical strainers I have on Bay Pelican.

The other strainers are my concern. Is this bolt failure the aberration or something that can occur normally on 30+ year old equipment?

Because we are in the Eastern Caribbean it is unlikely I can obtain replacement bolts locally. I plan to bring bolts with me next season.

I would appreciate anyone's experience with these bolts. My alternative which would allow replacement within a month is expensive shipping of new bolts from the United States.

 

[ksanders]

Marty

I have been looking over the strainers on my boat, which look like the same model and I have the same fears.

Because of that I have started on a program of replacing the raw water strainers with a type that has less parts.

For the generator and watermaker I chose these units by Raritan

http://raritaneng.com/wp-content/uploads/2014/03/rawwaterstrainer300.png

These are super tough plastic, and have an advantage of a straight in design for the seawater inlet, reducing the tendancy the old perko unit had of clogging at the 90 degree elbow in the inlet side.

I have been running them just one full season, but these are mature products with a great track record

I'm looking at the groco two piece units for the main engines.

 

[O C Diver]

Marty, never heard of that happening before. Have you rebuilt those strainers (new seals) or does it take a fair amount of tightening to seal the lid? Would start by examining the bolt on the other side.

Ted

 

[stone beach]

BP. Simple to make a new bolt from a steel bolt or even stud bar

 

[stone beach]

Wont last multiple years but will definitely keep you going

 

[stone beach]

Large jubilee clip around the whole thing will also keep you going

 

[Keysdisease]

The failure of a part like that after 32 years in an engine room environment is hardly Endemic. If its a Perko Strainer, and it does look like one, the part number for the replacement is 0493 DP 99L

PERKO Inc. - Catalog - Underwater Hardware - Intake Water Strainer [0493]

If it is Perko it will be cast into the top casting.

Those Raritan strainers are good units. They have been around for at least 40 years and have no record of issues.

 

[Shoalwaters]

I have worked on many boats with Perko strainers, some very old. They never stay looking pristine yellow metal, but I don't remember seeing buildup as bad as this. Can't help feeling there is some serious chemical or electrochemical action going on to produce all that green (copper salt?) buildup. The failed part and wingnut are usualky brass although the scroll-pin is not. I believe Perko does this to prevent interaction between dissimilar metals. I doubt replacing it with stainless would solve the underlying problem.

 

[psneeld]

The easiest thing to do is replace in kind the part that failed.

30 years isn't so bad, hard to say that the condition is just from warm salt water or something else going on.

I would be just as worried about the bolts that hold the top and bottom on at this point so either do those too or like Kevin Sanders suggested and replace the strainer.

When I bought my boat, all my strainers looked suspect. I like the Forespar marelon ones on my friends sailboat.

I still like them about 90 percent....the dang water inlet design that also holds the top on once clogged is troublesome to clear.....fortunately not a common thing for me.

 

[North Baltic sea]

The matter equaling, if anyone advise whether there is a special tool to open up this looking Stainer.


I tried to open my some time ago, but I did not get open. Tips to help open or welcome.


the second question, there is certainly a seal, whether it be replaced every time if you open the stainer, or can it withstand the more open?

 

[rwidman]

I had a different brand of strainer with a similar design. It failed because the bolt corroded. I found a replacement and it too failed after just a few years.


I decided to replace it with a different type where there was no critical bolt in contact with the water. It's been fine.


The replacement is somewhat similar to the photo in the post above. The top screws into a housing.

 

[rwidman]

The matter equaling, if anyone advise whether there is a special tool to open up this looking Stainer.


I tried to open my some time ago, but I did not get open. Tips to help open or welcome.


the second question, there is certainly a seal, whether it be replaced every time if you open the stainer, or can it withstand the more open?

I would think you could unscrew the cover by placing a large screwdriver between the two raised parts and turning. Or possibly use a ratchet handle in the square recess.

 

[psneeld]

looks like a 3/8 or 1/2 inch ratchet wrench may fit in the square hole.


And yes the seals are generally good enough to last years of opening and closing if not overtightened.


Even a flat bar twisted against the upright tangs might work.


I would definitely squirt some lubricating fluid around the edges of the seal and let it sit for some days before trying if it hasn't been opened lately.

 

[O C Diver]

Tapping the top of the lid with a hammer while trying to open it may help to break it loose.

Ted

 

[North Baltic sea]

Thanks to forum friends, try WD40 and a large screwdriver, a ratchet wrench or a slab of iron and knocked with a hammer.

 

[Capt.Bill11]

I've seen those bolts fail like that occasionally over the years. Based on the condition of you're strainer it looks like it's either not been bonded or has lost it's bonding connection at some point.

If the pin that that bolt pivots on is still there you might be able to use a wire tie to hold the lid down if you need to.

As to the plastic strainers, they're ok but I have seen the lids get stuck so tight on them that the tabs break off on them when trying to spin off the lid.

So keep the lid threads lubed and work the lid on a regular basis.

 

[Ski in NC]

Seen a few fail that way, mostly noticed when servicing.

Seen a few that were weeping water at bowl, went to snug up nuts and found the studs were corroded right at the threads and snapped right off. Boat sinker risk right there.

They sell a hardware kit that I think includes the studs, nuts and gaskets. Given the age it might be a good idea to go through all strainers, especially below WL.

 

[HopCar]

Bay, it's a common failure on those Perko strainers. Not enough meat left after drilling the hole for the pin. As the gaskets harden, it takes more and more effort to seal the lid and the bolt breaks. Install a new bolt and lid gasket. Keep an eye on it.
Perko Hinge Bolts

 

[dhays]

Thanks to forum friends, try WD40 and a large screwdriver, a ratchet wrench or a slab of iron and knocked with a hammer.

Be careful with the WD40. Not knowing what the seals are made of, I try to be careful about using WD40 around oil based "rubber" seals.

 

[Tuttouomo]

I am going to rebuild my Perko sea strainers after seeing this thread. I don't have much corrosion on mine, but after recently replacing the lid gaskets, I find that I have to really crank down on the wing nuts to stop the lid from weeping.
I believe that my wing nuts are bottomed out even with new gaskets.

Bill

 

[ancora]

When we bought our Nova 16 years ago, we had the Raritan plastic strainers pictured in KSANDERS contribution. The surveyor recommended changin' to bronze strainers. Of course, we didn't and the plastic ones are still workin'.

 

[rwidman]

The problem with strainers is, if they are below the waterline and they fail, they can sink the boat. It pays to use quality strainers and to check them from time to time.

 

[MurrayM]

...I like the Forespar marelon ones on my friends sailboat....

Pretty slick;

 

[bayview]

A common weak point and easily replaced with kits from Perko that include new gaskets. Time to rebuild that entire strainer. It is either not bonded or has been leaking for a while.

 

[psneeld]

When we bought our Nova 16 years ago, we had the Raritan plastic strainers pictured in KSANDERS contribution. The surveyor recommended changin' to bronze strainers. Of course, we didn't and the plastic ones are still workin'.

...makes you wonder


Plus, Forespar strainers according to their mounting instructions are to be mounted above or close to the waterline in case of problems.


One of their selling points to me...but then again, you can do that with any strainer if it seals tight and your engines are mounted close enough to the waterline.

 

[rwidman]

My strainer (it was the AC strainer) and the first replacement were similar to the Forespar strainer in the video above but bronze. The stainless steel bolt that holds the cap on was the failure point for both. It is submerged in water all the time. It seems to me a better design would be clamps on the outside of the strainer to hold the lid on.


As I recall, the pump to my AC unit required that it (and obviously the strainer) to be below the waterline. This is a case where you have to follow the equipment manufacturer's instructions, not the strainer manufacturer's instructions.


This is what I replaced it with:

It did require a change in mounting and plumbing. I walked the marina checking friend's strainers and this is what most of them had from the factory.

 

[psneeld]

As long as the pump is below the waterline and there is spillover from the strainer into it...I haven't had a problem on mine or dozens I have worked on. But the tops of my strainers are so close to the waterline, they just barely spillover if anything fails except the hose feeding them...but that is true of any strainer.

 

[Larry M]

We have 2 of these and like them. Opening for cleaning is easy and they accept readily available plastic baskets. My complaint is the poor quality SS bolts that ours had. I have no idea of the age since this one was on the boat when we bought it (10 years). I took it apart when we re-did the engine room. The outside of the strainer gets wet during cleaning but I rinse with fresh water when done and there were no obvious leaks. We upgraded to 316 SS bolts.

]

 

[Xsbank]

It looks to me like the bonding has failed. The green is also an indication of salt water in there but look at all that loose crappy wiring in there too! Sorry Marty, it looks to me like a long history of no maintenance down there. Does the rest of the bilge look like that too? If so, your winter project is clear, if this strainer failed because it's never been looked at, a bunch of other stuff down there is poised to do the same and as you saw, you could lose he entire boat. Everything below the waterline. Throughhulls, strainers, all hoses, hose clamps, stuffing box, all that crap wiring and last but not least, bonding!

 

[sean9c]

I've a friend that had a Perko strainer that looked to be in about the same condition as yours. He was cleaning it up and the bottom fell off. The bronze clamping rods were eaten away where they thread into the bottom cap. He drilled out the bottom cap and replaced the rods with ss all thread and lock nuts.