Raw water strainer disaster waiting to happen

[Project_Mayhem]

My new to me C30 has a plastic through hull, plastic winterizing port and plastic raw water strainer all below the water line. The 30 year old raw water strainer is showing fracture marks in the thin, clear plastic. The only all metal replacement I've been able to find so far is a $2800 unit from Groco. Does anyone have any robust recommendations for a new one? The alternative, and probably preferable method, is to make a loop that goes above the water line. Can the raw water pump prime itself if I did this? It's a Sherwood pump on an M25-XP

 

[Don S/V ILLusion]

Groco sells a bronze strainer with plastic bucket for around $250. They are ubiquitous which is a testament to their durability.

 

[Project_Mayhem]

Can an above waterline loop work with this pump? I'd be comfortable using a plastic unit if this is the case

 

[mermike]

Both the Sherwood and Vetus raw water strainers are priced under $100. I have the Sherwood. No issues in 6 years of ownership.

 

[Davidasailor26]

Can an above waterline loop work with this pump? I'd be comfortable using a plastic unit if this is the case

The pump should be self priming so a loop above the waterline should be fine. But a loop will only help if the strainer itself is what’s above the waterline. If you have a loop before the strainer and the strainer fails it’ll still pull water over the loop - that’s how a siphon works. You probably can’t use a vented loop to prevent the siphon, because then the pump will suck air in from the vent.

 

[jssailem]

I bought the Groco ARG 750 bronze strainer. Just looked and Defender lists it for $220

It is on the boat working 24/7. I like it because I can open and clean the filter from the top as opposed to spinning off the bottom basket. No water spill when I empty the sucked in eel grass.

 

[Project_Mayhem]

The pump should be self priming so a loop above the waterline should be fine. But a loop will only help if the strainer itself is what’s above the waterline. If you have a loop before the strainer and the strainer fails it’ll still pull water over the loop - that’s how a siphon works. You probably can’t use a vented loop to prevent the siphon, because then the pump will suck air in from the vent.

I think you're right about it being self priming. When we winterized it, we simply stuck a garden hose to the port and the other end went into a bucket of coolant. There was definitely air in the hose and it didn't matter that it sucked in more air when the hose accidentally came out of the coolant

I totally agree that having the filter below the waterline is a disaster waiting to happen. There's also a plastic port for winterizing made by Prestone so it's definitely not a high quality part.

I bought the Groco ARG 750 bronze strainer. Just looked and Defender lists it for $220

It is on the boat working 24/7. I like it because I can open and clean the filter from the top as opposed to spinning off the bottom basket. No water spill when I empty the sucked in eel grass.

I'll likely look at some of the lower end Groco models. They have some good quality products for reasonable prices. The threaded rod designs seem like they'd be prone to failure and a bit more cumbersome to open

 

[Davidasailor26]

I have a Vetus plastic strainer mounted above the waterline. It’s quite robust and easily serviceable, though I’m still glad it’s not below the waterline.

 

[Project_Mayhem]

I have a Vetus plastic strainer mounted above the waterline. It’s quite robust and easily serviceable, though I’m still glad it’s not below the waterline.

I just updated my response to your post. The Vetus design does look nice for a plastic unit. There's minimal hard plastic that's prone to cracking and since it's just the top that unscrews, it looks like it's a nearly spilless design when cleaning it out

 

[Hayden Watson]

I have a Vetus plastic sea strainer and have it mounted just a bit above the waterline, which on a C30 is a few inches below the seats in the dinnette. This is handy because then you can open the top to clean it without the water draining all over the place.

 

[Davidasailor26]

I just updated my response to your post. The Vetus design does look nice for a plastic unit. There's minimal hard plastic that's prone to cracking and since it's just the top that unscrews, it looks like it's a nearly spilless design when cleaning it out

Yes, with it being above the waterline there are no spills at all. Some people also use it for easy winterizing, by just closing the seacock and pouring AF into the strainer bucket.