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Old 22-10-2009, 12:44   #1
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Bronze Seawater Strainers

Ok, I've decided to buy one of those Groco beauties but now they have plastic, stainless or monel filter baskets. Just as I make a decision to make a big ticket purchase there is another choice.
Is it worth the extra cost to get stainless or monel filter?
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Old 22-10-2009, 12:55   #2
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Probably depends on what the conditions are like where you're at, and which line you're installing it on (Raw water intake for main? Gen? AC? The more it's used, the more growth you'll see/the more you'll have to clean it). As far as the water itself, the temperature plays a big part, and with growth, well, it varies, even down to which marina you're at around here.

But generally speaking, I'd say yes, it's worth it to go w/the stainless at least.

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Old 22-10-2009, 12:57   #3
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If you're in a hot marina where you burn through zincs, you'll find you also burn through metal strainers, even monel.
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Old 22-10-2009, 13:01   #4
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metal

They used to just come with metal. My guess is metal will last longer for you. If you are banging it on the dock to get something out,,, etc Not sure what the $ premium is . Monel is the "best", but SS ought to be fine...
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Old 22-10-2009, 13:06   #5
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If you're in a hot marina where you burn through zincs, you'll find you also burn through metal strainers, even monel.
I'd be interested to see what common marine metal is more electronegative than monel. How would it "burn through"?
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Old 23-10-2009, 00:08   #6
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Thanks for the input. I'll be calling tomorrow to see who has the best prices.
regards,
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Old 23-10-2009, 00:24   #7
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For engine raw water. The water temp here is in the 70s year round. No marina. Probably a bit of stray electrons in the water but not overly hot.
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Old 23-10-2009, 01:08   #8
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Hi John...Just bought one for "Trust". It came with a plastic screen. All I can guess is it was cheaper to make. As far as-- "you'll find you also burn through metal strainers", I would question that as I cannot see the electrical path since the input hose and outlet hose would be full of air when the engine is not running due to the syphon break.
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Old 23-10-2009, 04:24   #9
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I'd be interested to see what common marine metal is more electronegative than monel. How would it "burn through"?
Monel is listed as #63 on the galvanic series of metals in sea water from Army Missile Command Report, where the larger numbers indicate more noble (cathodic, less active) metals. In a galvanic couple, the metal higher in the series (or the smaller the number) represents the anode, and will corrode preferentially in the environment.
Stainless Steels (316 @ #67, 301 @ #72, 316L @ #76), Silicon Bronze (@ #70), and the Titaniums (#82 - #88) are all more noble than Monel.

Corrosion Control - Galvanic Table
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Old 23-10-2009, 06:20   #10
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Check Ebay for good price

Hi John,

I bought one on Ebay for a very good price about a year ago, brand new in the box. Monel screen.

We are finally in the water, launching party was several weeks ago in Newport, RI. Sitting at the dock trying to get the boat finished enough to head south to the Bahamas for the winter. We have at least several more weeks to go.

Here is the boat at the dock at Newport Shipyard, party tent in the background, bow of more typical Shipyard boat on the right (the majority of boats here are over 100'. We may be the smallest at 32').

Hope your boat is going well.
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Old 23-10-2009, 08:27   #11
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Hi John,

I bought one on Ebay for a very good price about a year ago, brand new in the box. Monel screen.

We are finally in the water, launching party was several weeks ago in Newport, RI. Sitting at the dock trying to get the boat finished enough to head south to the Bahamas for the winter. We have at least several more weeks to go.

Here is the boat at the dock at Newport Shipyard, party tent in the background, bow of more typical Shipyard boat on the right (the majority of boats here are over 100'. We may be the smallest at 32').

Hope your boat is going well.
Beautiful boat!
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Old 23-10-2009, 08:33   #12
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Monel is listed as #63 on the galvanic series of metals in sea water from Army Missile Command Report, where the larger numbers indicate more noble (cathodic, less active) metals. In a galvanic couple, the metal higher in the series (or the smaller the number) represents the anode, and will corrode preferentially in the environment.
Stainless Steels (316 @ #67, 301 @ #72, 316L @ #76), Silicon Bronze (@ #70), and the Titaniums (#82 - #88) are all more noble than Monel.

Corrosion Control - Galvanic Table
Thanks! Passivated stainless would be a possible better chioice. Ours has a bronze body and monel screen(close numbers). No problems after 20 or so years. (Groco).
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Old 23-10-2009, 08:50   #13
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not really certain

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I'd be interested to see what common marine metal is more electronegative than monel. How would it "burn through"?
All I can tell you is that on a previous boat where I was having electrolysis problems that we finally tracked down to a nearby Sea Scout vessel, the monel basket in my bronze Groco strainer was the first indication of trouble. The strainer was fairly close to the thru-hull, but had no electrical connection to it and was not part of the boat's bonding system. A great deal of water circulated through it since it was attached to the refrigeration system.

Turns out the Sea Scouts had hooked up an automotive-type battery charger from a car parts store when their inverter/charger went south. Saved themselves a bit of cash and cost everyone else on the dock a fortune. Nearby boats would burn through their shaft zincs in about 6 weeks. The Bayliner next to the scout ship lost both trim tabs. But I was surprised that the monel didn't stand up to the situation, especially given how expensive those filters are.
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Old 23-10-2009, 08:54   #14
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All I can tell you is that on a previous boat where I was having electrolysis problems that we finally tracked down to a nearby Sea Scout vessel, the monel basket in my bronze Groco strainer was the first indication of trouble. The strainer was fairly close to the thru-hull, but had no electrical connection to it and was not part of the boat's bonding system. A great deal of water circulated through it since it was attached to the refrigeration system.

Turns out the Sea Scouts had hooked up an automotive-type battery charger from a car parts store when their inverter/charger went south. Saved themselves a bit of cash and cost everyone else on the dock a fortune. Nearby boats would burn through their shaft zincs in about 6 weeks. The Bayliner next to the scout ship lost both trim tabs. But I was surprised that the monel didn't stand up to the situation, especially given how expensive those filters are.
Nuts! How'd you find out it was they that were frying the marina?

You'd think that the zincs would have saved the screen. Must have been isolated from them
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Old 23-10-2009, 09:12   #15
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it became a "neighborhood" problem

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Nuts! How'd you find out it was they that were frying the marina?
One of my neighbors was an electrical engineer, and he had a system where he could hook up his multimeter to an in-water probe and compare it to the electrical signature of the boat. He could even tell if your zincs were gone. He did this to several boats, mine included, and was able to triangulate on the Sea Scouts.

No surprises there. That "ship" had been an on-going disaster. The leader had sent the buys up the mast with steel wool to prep it for varnish, and the shreds landed on the non-skid of the boat in the downwind slip, which after a week turned red with rust. Not just flecks--the whole deck was red.

Back to the automotive battery charger, the scout leader denied any possibility that his "ship" was causing the problem, but his shore power lines mysteriously began disappearing from that moment forward, regardless of how often he replaced them. Couldn't seem to last the night. Problem solved.
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