"Plastic" Raw Water Strainers

[SvenG]

When we take Senta II in for her bottom job next week I'm hoping to also remove the external strainer on the raw water intake with the intention of putting an internal strainer in line, in the engine compartment.

The strainer I'm thinking of is this one

What bothers me is that it is plastic and it doesn't specify that it is heat resistant, high impact resistant, impervious to diesel or other chemicals, or stable so it won't develop stress fractures over time.

Do these strainers have a known history so one could feel comfortable sticking it down in the "hole" where it could sink the boat if it fails ?

Thanks,



-Sven

[Wand]

Well, nothing lasts forever but they are standard issue these days; I use them as would most others and I haven't heard of any problems. You will of course have a seacock at the thru-hull for insurance. My two cents.

[capngeo]

Just curious.. why delete the externals?.. I love those things!

[SvenG]

Originally Posted by At sea

Well, nothing lasts forever but they are standard issue these days; I use them as would most others and I haven't heard of any problems. You will of course have a seacock at the thru-hull for insurance. My two cents.

Seacock -> yes. But is still down in the hole where it won't be seen under way unless the companionway stairs and the engine cover are removed.

How long have you been using them and how many ?

Thanks !



-Sven

[SvenG]

Originally Posted by capngeo

Just curious.. why delete the externals?.. I love those things!

I saw some pictures MainSail posted at some point, filled with barnacles and other crud inside the grate. The externals also can't be cleared as easily.



-Sven

[Wand]

Originally Posted by SvenG

Seacock -> yes. But is still down in the hole where it won't be seen under way unless the companionway stairs and the engine cover are removed. How long have you been using them and how many ?

I have them on three boats currently; the longest maybe six years.

But I want to amend my first reply. That strainer you've shown I would not recommend because of the screw top. They can be very difficult to remove and I've had the 'handle' split from the cap. A much better design is the one with the butterfly nut on top that presses the cap down onto the o-ring. That is always easy to remove.

The two styles are in the links below: the first is the goodie and the second the baddie imo.

https://www.whitworths.com.au/main_i...AbsolutePage=1

Not*https://www.whitworths.com.au/main_i...AbsolutePage=1

[Sailmonkey]

I can't be sure but I do remember something about plastic strainers only above the waterline. They are fun to watch the top when the enigne is running though!!

I should mention that this is only to see what's coming in, not the lid flexing or anything like that

[US1Fountain]

A friend had a plastic strainer for his A/C water supply. After 2 yrs, the clear plastic removable bottom was crazed really bad. Looked like it was ready to fail at any moment.
I believe it was a Groco brand strainer.

[SvenG]

Originally Posted by At sea

The two styles are in the links below: the first is the goodie and the second the baddie imo.

https://www.whitworths.com.au/main_i...AbsolutePage=1

Not*https://www.whitworths.com.au/main_i...AbsolutePage=1

Thanks for the additional info. That first one does look a little more rugged.



-Sven

[osirissail]

I used Forespar Marelon Strainers for almost 20 years out in the ocean and Caribbean Sea without any problems except one. The internal strainer mesh "basket" was made from plastic originally and didn't last a year. Now they come with stainless steel mesh baskets and you can get about 5 years from one before the "acidic" ocean eats holes in it. So I keep a few extra strainer baskets on hand. I understand the bronze strainers have the same problem.
- - I also changed all the through-hulls and seacocks to Marelon and now when I detect barnacles or other crustaceans in the hoses, etc. I can pour muriatic acid down the strainer and watch all that stuff bubble away without causing any damage to the all-plastic system. Been doing that for 20 years so it works.
- - But only use Forespar Marelon if you are going to change out through-hulls and seacocks - they are rated for that use and are used by the major boat builders now-a-days.

[S/V Alchemy]

While I have a "basket strainer" on one boat AFTER the impeller and BEFORE the block, I have a bronze Perko pre-impeller on the other boat and consider that superior. The plastic one is best at catching bits of shredded impeller in my view, and, raised to circa the waterline and accessible to daylight and a fast hand, are a good idea and cheap insurance.

The one pictured looks like a plastic Perko. It does not entirely inspire confidence.

[SV Demeter]

+1 on the Groco Bronze strainers.

++1 on the Forspar Marelon seacocks and fittings.

You will likely find many strong opinions on this subject however.

[anjou]

A slightly different application but ive fitted a plastic filter body to a swimming pool I built for a client, which was below ground in the plant room.

5 years on and to my knowledge its still working fine. Im sure the design and integrity of plastic is well researched so that its up to the job.

Imagain it failing and 50 tons of water rushing out

[ggray]

Check w/ the manufacturer.

I installed a filter for the AC, similar to what you are looking at, with a plastic basket. SS was optional, but I was told plastic would last longer--ss would corrode.

Other than that it is still at work, I have no experience either way; perhaps I was given a line.

[boden36]

We have used a Vetus strainer for the last 25 yrs no problem. It should be above waterline with a seacock at the hull fitting. If you mount it straight above the seacock and keep the hose straight, you can rod the line out if it gets blocked with a plastic bag or similar.
Regards,
Richard.