Raw Water Strainers

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jlombardo

Veteran Member
Joined
Sep 15, 2019
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41
Location
US
Vessel Make
1998 Mainship 31 Sedan Bridge
I have 1998 31' Mainship Sedan Bridge that did not come with water strainers. It has 2 water pickups that have a plate with 1/8" holes on them, but they are inadequate as I am constantly cleaning grass out of my trans/oil coolers.

I am looking to add strainers and am looking for some guidance. It looks like there are 2 basic types, 1 all brass/glass, and 2 partial brass/plastic. The brass/plastic versions are approximately 30% less expensive.

My boat has 1 1/4" ID hoses on the intake. Here are 2 options that I have been looking at and would appreciate any information provided.

Brass/Glass version:

https://www.zoro.com/perko-1-14-int...kmYsGSPjAnb8Y6orIkgaAsR2EALw_wcB&gclsrc=aw.ds

Brass/Plastic version:

https://marinepartssource.com/1-1-4...IFJRDRoP_4Ve4xsuu6LSQSE3iD8vWW2MaAqi1EALw_wcB

To be honest with you, I am not sure that either version is appropriate for 5.7/350 motor implementations.

Any information would be greatly appreciated.

John
 
Thanks for the quick response!

What size engine do you have?


John
 
Either of the strainers you picked would be excellent.
Neither the Groco or Perko are brass, they are good quality bronze.
The cylinder in the Perko is plastic, not glass. The only weakness on the Perko is that if you over tighten the wing nuts the bolt can break. I sold a lot of replacement bolts.
The Groco is available with a plastic instead of stainless basket. I think it will outlast the stainless one.
Either the Perko or Groco should last the life of your boat. You’ll need to occasionally need to replace the strainer baskets and the plastic cylinders will discolor.

https://www.groco.net/products/raw-water-strainers/basket-strainer/arg-series
 
You may consider up-seizing to 1-1/2 ". I would recommend using the Groco products.
 
As for your external scoop strainer, you may be able to change to a plate with smaller holes. I know Groco makes the plates replaceable and they offer them with smaller than 1/8” holes. I would think that anything that gets through the external strainer could get through the internal strainer. Sen-Dure also makes that style external strainer but they don’t have changeable strainer plates. https://www.groco.net/products/raw-water-strainers/hull-strainer/aphs-series
 

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I think the real issue here is that our bay (Barnegat Bay - NJ USA) is an average of 3 feet deep, so grass growth is plentiful.

My air conditioners do have a strainer that seem to do a much better job than the raw water pickup strainers for the engines.


John
 
John, We keep our boat in Toms River and are on Barnegat Bay a lot. Our strainers are groco bronze type and we very rarely get any grass or weed in any of them. I clean them at the end of each season. The guy in the next slip has a 34' Silverton with no strainers, he does not seem to even think it is an issue. I do think you need raw water strainers, looking on ebay it looks like you could probably get 1.25 inch grocos for about 300. each then the bronze fittings and hose barbs add up. Engines generators, pumps etc all come into play. Maybe you should do the engines first and see how much stuff you collect in them. Good Winter project. John P
 
As Parks mentioned, an external strainer does a much better job. I replaced the smaller hole strainer with stainless steel perforated sheet metal with 3/16" holes.

20231107_160438.jpg

Ted
 
What are everyone's thoughts on this model? It was recommended by Lou_tribal above. I do like it for several reasons.

https://www.tradeinn.com/waveinn/en...y5oNww-XvTmX27qCafIaAvrtEALw_wcB&gclsrc=aw.ds


1.) The price. 1/3 the cost of other options.
2.) The hose connectors are front to back when mounted so it doesn't matter which side of the boat it is mounted on, you simply hook up to the front or back input/output depending on in or output.
 
Don't remember if that was the same model, but had one quite similar on my generator that was cracked when I bought the boat. Thankfully it was above the waterline, so it didn't leak into the boat.

Ted
 
Does that mean it's a no for this typer?

They all seem to recommend that they are mounted above the water line, but neither of mine (generator/Air Conditioner) are. I don't see a way to easily achieve that either. Would require that I run them to the outside walls and would add many feet to the hoses.
 
jlombardo said:
Does that mean it's a no for this typer?

They all seem to recommend that they are mounted above the water line, but neither of mine (generator/Air Conditioner) are. I don't see a way to easily achieve that either. Would require that I run them to the outside walls and would add many feet to the hoses.
Click to expand...

If they don't crack, I don't see it as a problem. Most generators are able to suck water up to the raw water pump. However, most air conditioner pumps are centrifugal and have to be mounted so that sea level is above the pump. A cracked strainer above the waterline would likely loose the prime of the pump. An air conditioning pump with the strainer above sea level often is more difficult to prime.

Ted
 
Mine is set right at water line, meaning that water line is right at the top of the strainer. If I unscrew the lid water does not overflow. Well if boat is not rocking :).
I guess that if hose under the strainer are not fixed properly plastic could crack with vibrations, but never had that issue, at least not yet.

By the way I do not recommend anything, just mention the one I have aboard and my experience with it.

L
 
Thank Lou for bringing this type to my attention. I do believe that I am going to go with these for the two reasons that I mentioned. I usually check oil and antifreeze levels before each trip, so I will add review of strainers for leaks.

Thank you,
John
 
Either of the bronze strainers will work. Not sure how good the plastic Vetus strainer would be, or what 38.1mm means, but it notes that it is made for up to 35 liters per minute, which is not much. The raw water pumps on my CAT 3208TA engines are rated for up to 120 gallons (454 liters) per minute, for comparison.



When it comes to strainers, bigger is better so aim for what you can afford and what will fit. My boat has four Perkos and one Groco, all work great.
 
Based on Vetus's chart, the 1 1/4" strainer is recommended for 38 USGAL/144Liter or a maximum of 87USGAL 330 Liter per minute. Unfortunately, I have not been able to locate a GAL per minute rating on the Perko strainers.

Which strainer model do you have and where did you fine the gallons per minute rating. Also, what is the input size?

Thank you,
John
 
jlombardo said:
Based on Vetus's chart, the 1 1/4" strainer is recommended for 38 USGAL/144Liter or a maximum of 87USGAL 330 Liter per minute. Unfortunately, I have not been able to locate a GAL per minute rating on the Perko strainers.

Which strainer model do you have and where did you fine the gallons per minute rating. Also, what is the input size?

Thank you,
John
Click to expand...


My main engine strainers are Perko 500 series 2.5". I have no idea what the GPH rating is on them, but they seem way over-sized and my raw water lines are only 1.5" diameter.


I guess I read the flow specs on the Vetus strainers incorrectly.
 
Last edited:
If you have an 1-1/4” pump and 1-1/4” hoses any of the strainers discussed will handle the required flow. Perko, Groco and Vetus have all been making strainers for boats for a long time.
 
Last edited:
I have the Groco model and haven't had any issues, knocking on wood & my head, after I replaced the elbows. Add elbows to the cost but you can then pick the size you need for the hoses you have.

I replaced the elbows because the PO had made up SS units from pipe cut in wedges then welded. Don't know why, never met him and didn't know when I bought the boat. Surveyors never picked that up.

Groco had the elbows I needed in stock so now I have 4 nice bronze elbows which should last for the next owner, wait, no my Viking funeral will obviate that.

As someone else said, easy to winterize with the opening and baskets are also easy to replace if necessary.

I think you are making a smart move to put strainers in, don't know why Mainship didn't do that.

Good luck.
 
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