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
Raw water strainer disaster waiting to happen
- Thread starter Project_Mayhem
- Start date
Groco sells a bronze strainer with plastic bucket for around $250. They are ubiquitous which is a testament to their durability.
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
SBO Weather and Forecasting Forum Jim & John
- Oct 22, 2014
- 22,060
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'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
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
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.
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.
Good point. Most of the water would drain away from the highest point. Or at least try to. I have a port on my raw water intake hose to connect a garden hose. It made winterizing very very easy
I presume you mean a cutoff hose sucking from a bucket of antifreeze, not a pressurized hose from a spigot? In case you don’t, or for any future readers of the thread - Be careful with a pressurized hose. The water pressure could push past the impeller, fill the muffler, and back up into the cylinders. Liquid in the raw water circuit should only ever be sucked by the impeller, not pushed or siphoned in.
Correct, it was an unpressurized setup
Definitely get the plastic strainer out of the engine compartment.
Here is my set up. A bronze Groco strainer with the top about 2 inches above the at rest waterline. I opted for a stainless steel strainer basket rather than plastic. No priming problems for my Yanmar 2GM engine’s pump.
The 3-way valve on the engine side of the strainer is my winterizing hose. The hose extends into the bilge where it could assist as an emergency bilge pump if ever needed. I just stick the hose directly in my antifreeze jugs.
Here is my set up. A bronze Groco strainer with the top about 2 inches above the at rest waterline. I opted for a stainless steel strainer basket rather than plastic. No priming problems for my Yanmar 2GM engine’s pump.
The 3-way valve on the engine side of the strainer is my winterizing hose. The hose extends into the bilge where it could assist as an emergency bilge pump if ever needed. I just stick the hose directly in my antifreeze jugs.
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jssailem
SBO Weather and Forecasting Forum Jim & John
- Oct 22, 2014
- 22,060
Great idea! Is that foil lined bubble wrap that you're using for insulation?
I aggree with your statement about the inavisiblity of a plastic sea strainer inside the engine compartment but I went the other way. I installed a plastic Vetus sea strainer with the top just above the static waterline so that I could clean it with minimal mess. I did not want any spillage to put saltwater on the engine, so I installed it outside of the engine compartment in the adjacent space.
It’s engine room acoustic insulation. Surprisingly heavy and very effective. The old foam insulation was crumbling and I had the engine out in 2014 for transmission work, so it was good time to replace it when I had easy access.
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I was warned by an experienced marine diesel mechanic that plastic strainers inside the engine compartment are risky because they get brittle with age and the engine heat greatly accelerates that process.
Getting it outside the engine compartment, away from engine heat and above static waterline is a good compromise. I actually considered that option with a plastic strainer, but inside the engine compartment provided the best access in my boat, so I went with bronze.
Keeping salt water away from the engine is smart. Not a problem here on Lake Michigan.