Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 06-05-2013, 18:58   #1
Registered User
 
silverp40's Avatar

Join Date: Jan 2010
Location: Usually where the boat is...
Boat: Pearson 40
Posts: 514
Images: 7
Massive Corrosion Raw Water Strainer

This 1" Perko raw water strainer has suffered from massive corrosion. Hard to tell why, but owner maintains neighbor's large powerboat caused it.

Could probably be cleaned somewhat with acid but it does not seem too safe...

Any opinions??

Cheers!
Attached Thumbnails
Click image for larger version

Name:	DSC01892.jpg
Views:	338
Size:	418.3 KB
ID:	60464  
__________________

__________________
silverp40 is offline   Reply With Quote
Old 06-05-2013, 19:10   #2
Registered User
 
SaltyBard's Avatar

Join Date: Apr 2013
Boat: Cape George 34
Posts: 59
Is the boat in the water? I'd worry about thru-hulls!
__________________

__________________
"Shipmates on a boundless sea, through life we're sailing by the lee"
- The Salty Bard Pirate Poetry Project
SaltyBard.com
SaltyBard is offline   Reply With Quote
Old 06-05-2013, 19:12   #3
Registered User

Join Date: Jan 2009
Boat: Tartan 37 #6
Posts: 326
Re: Massive Corrosion Raw Water Strainer

How would the neigbours boat be responsible, it looks like rubber in and out so isolated,looks like leaking, be more interesting to see the inside. IF the boat next door is responsible for this, I hate to think what other equipment is like.
__________________
steamgoat is offline   Reply With Quote
Old 06-05-2013, 19:15   #4
Registered User
 
stillbuilding's Avatar

Join Date: Jan 2008
Location: Hong Kong
Boat: Custom Freya 20m
Posts: 961
How would the neighbour's boat cause corrosion on the exterior I wonder?

Get a new one of course but seems strange for a bronze item unless it degraded over several years.
__________________
stillbuilding is offline   Reply With Quote
Old 06-05-2013, 19:19   #5
Marine Service Provider
 
Maine Sail's Avatar

Join Date: Jan 2007
Location: Maine
Boat: CS-36T - Cupecoy
Posts: 3,060
Re: Massive Corrosion Raw Water Strainer

Quote:
Originally Posted by silverp40 View Post
This 1" Perko raw water strainer has suffered from massive corrosion. Hard to tell why, but owner maintains neighbor's large powerboat caused it.

Could probably be cleaned somewhat with acid but it does not seem too safe...

Any opinions??

Cheers!

Take it apart and have the parts bead blasted or use a wire wheel on a bench grinder. You'll likely find it in good shape. The plastic can be cleaned and polished clear again and a new gasket set ordered.
__________________
Marine How To Articles
Maine Sail is offline   Reply With Quote
Old 06-05-2013, 19:27   #6
Registered User

Join Date: Feb 2013
Posts: 51
Re: Massive Corrosion Raw Water Strainer

What is the white wire (photo left of your hand?) Are the in and out elbows bronze, brass, or can you tell? What material are the hose barbs that are screwed into these two elbows?

Obviously, if this type corrosion is not found elsewhere in your boat's underwater metals then it is unlikely this is a neighbor issue. Neighbor involvement not likely if the strainer is not bonded and/or you have galvanic isolation in your shore power.

In all cases it is way easy to measure your DC hull potential and the strainer potential too thus to to rule out neighbor involvement. Also this will show whether you have DC stray current on your own boat -- which is more likely if the damage occurred suddenly.

Bottom line - you might clean up but you cannot consider reuse until after clean up and verify the unit is worth putting back - but no brass alloys allowed in the fittings here - not ever. You need to know if there is enough metal left for service and no stray DC current flowing in your boat.

Based on this photo I would not reinstall - but either way you must make sure whatever goes back in is all bronze components.

Charles
__________________
Nor'Sea 27 is offline   Reply With Quote
Old 06-05-2013, 19:28   #7
Senior Cruiser
 
Cheechako's Avatar

Cruisers Forum Supporter

Join Date: Aug 2006
Location: Skagit City, WA
Posts: 19,359
Re: Massive Corrosion Raw Water Strainer

is it really corroded.... or just green... cant tell..... green in no problem. If it's actually corroded away I would probably try bonding the new one. If it's bonded... I would unbond it. I doubt if a nearby boat or AC power caused it unless it's bonded to something..... it appears like it's been seeping for a long time.
__________________
"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard











Cheechako is offline   Reply With Quote
Old 06-05-2013, 19:30   #8
Registered User

Join Date: May 2009
Location: Massachusetts
Boat: 40' Silverton Aftcabin with twin Crusaders
Posts: 1,590
Re: Massive Corrosion Raw Water Strainer

I agree with Mainsail, clean it up!

I have a different thought on why this thing turned green. HOW CLOSE IT IT TO THE BATTERIES??? If this was galvanic corrosion, I would expect the corrosion to be be INSIDE the filter. Your pictures show the device's exterior covered with what looks to be the result of acid fumes. Again my thought is this is too close the batteries and the outgasing from them is responsible. But please keep us up to date with your neighbor's progress.

Foggy
__________________
foggysail is offline   Reply With Quote
Old 06-05-2013, 19:31   #9
Registered User
 
Rhapsody-NS27's Avatar

Join Date: Oct 2010
Location: VA, boat: Deale, MD
Boat: 1981 Nor'sea 27
Posts: 1,409
Re: Massive Corrosion Raw Water Strainer

to me it looks like it just disintegrated. Looks like an ugly mess.
__________________
Daniel - Rhapsody Blog,
“A sailor’s joys are as simple as a child’s.” — Bernard Moitessier
"I don't need therapy, I just need my boat"
Rhapsody-NS27 is offline   Reply With Quote
Old 06-05-2013, 19:37   #10
Registered User
 
Watercolor's Avatar

Join Date: Sep 2009
Location: Montpelier, VT
Boat: On the hard for now - 2 dinghies
Posts: 198
Re: Massive Corrosion Raw Water Strainer

Unless there's something else we can't see, the only metal contact to the tru-hull and the strainer would be the metal reinforcement in the hose. The strainer is mounted on a bulkhead is assume.

1. What do the seacocks look like? Especially the one connecting to the strainer?

2. Is there anything that can be dripping from above the strainer?

3. Take the strainer out if possible and clean it up, see if you can ascertain how much corrosion there really is. It may give you some clues. I have the feeling Steamgoat might be on to something.

4. What material are the street elbows and barbed fittings made of?

5. Are there any wires that could be touching the strainer?

6. The last thought is the SeaFrost condenser unit. Check the condition of the zinc in the unit along with the coil. I just remembered that we had to change out the zinc once a year.

Good luck!
__________________
Watercolor is offline   Reply With Quote
Old 06-05-2013, 19:48   #11
Registered User
 
Delfin's Avatar

Join Date: Aug 2010
Location: Anacortes, WA
Boat: 55' Romsdal
Posts: 1,390
Re: Massive Corrosion Raw Water Strainer

I know that some folks are fond of putting hot tub bromide tablets into their raw water strainer to clean out the system. Since the bromide reacts with salt water to produce highly corrosive bromine gas I suppose this might be a possibility.
__________________
http://delfin.talkspot.com
When stupidity is a sufficient explanation, there is no need to appeal to another cause.
- Ulmann's Razor
Delfin is offline   Reply With Quote
Old 07-05-2013, 06:37   #12
Registered User
 
silverp40's Avatar

Join Date: Jan 2010
Location: Usually where the boat is...
Boat: Pearson 40
Posts: 514
Images: 7
Re: Massive Corrosion Raw Water Strainer

This occured over 2-3 years, we were not here at the time and the power boat has left. He was saying that his zincs would go within 1 month or so. Hence, probably stray current, maybe bad grounding on the shore power?

His bonding cables, just visible on the bottom of the photo, were completely corroded, just fell out of their terminals.

Entire unit is a Perko, I am pretty sure it is bronze, hose fitttings probably same.

The electrical grounding on his boat was not good so I put a good grounding on it to eliminate that possibility.

No dripping from above, inside strainer basket looks fine.

Cleaning it up is a bit of a big deal, the corrosion is hard as rock It is hard to even chip any! I was thinking of a soak in vinegar or maybe even muriatic acid but I have a feeling that it might damage it further...

It is close to the batteries but they are maintenance free and no other signs of outgassing.

No bromide tablets in this one...
__________________
silverp40 is offline   Reply With Quote
Old 07-05-2013, 07:15   #13
Marine Service Provider
 
Maine Sail's Avatar

Join Date: Jan 2007
Location: Maine
Boat: CS-36T - Cupecoy
Posts: 3,060
Re: Massive Corrosion Raw Water Strainer

Quote:
Originally Posted by silverp40 View Post
This occured over 2-3 years, we were not here at the time and the power boat has left. He was saying that his zincs would go within 1 month or so. Hence, probably stray current, maybe bad grounding on the shore power?

His bonding cables, just visible on the bottom of the photo, were completely corroded, just fell out of their terminals.

Entire unit is a Perko, I am pretty sure it is bronze, hose fitttings probably same.

The electrical grounding on his boat was not good so I put a good grounding on it to eliminate that possibility.

No dripping from above, inside strainer basket looks fine.

Cleaning it up is a bit of a big deal, the corrosion is hard as rock It is hard to even chip any! I was thinking of a soak in vinegar or maybe even muriatic acid but I have a feeling that it might damage it further...

It is close to the batteries but they are maintenance free and no other signs of outgassing.

No bromide tablets in this one...

It looks to me like a weeping clean out gasket could have caused that....

These are expensive strainers and they will very often clean up like new with the right tools.

I happen to be in the shop this morning and pulled a used one out of a box. Certainly not the worst patina I have seen but it shows what you can do in as little as 5 minutes with a bench grinder and wire wheel. I have a had some realty nasty ones, that look like yours, clean up like new with no signs of dezincification or corrosion. Perko uses a high quality bronze on these...

Including disassembly this took me less than 5 minutes. Took longer to upload the photo..


Here's what they look like when ready to go back together.


And ready to be re-installed for many more years of service.



P.S. If you don't want yours, I will be glad to pay for shipping it to me........

OK back to work...
__________________
Marine How To Articles
Maine Sail is offline   Reply With Quote
Old 07-05-2013, 07:26   #14
Registered User
 
silverp40's Avatar

Join Date: Jan 2010
Location: Usually where the boat is...
Boat: Pearson 40
Posts: 514
Images: 7
Re: Massive Corrosion Raw Water Strainer

Thanks Main Sail ,just thought that after a lot of grinding work, corrosion of the components would deem the unit useless.

I will definitely tell him and give it a try though....
__________________
silverp40 is offline   Reply With Quote
Old 07-05-2013, 18:28   #15
cruiser

Join Date: Feb 2008
Location: North Charleston, SC
Boat: Camano Troll
Posts: 4,669
Re: Massive Corrosion Raw Water Strainer

It appears to me that the corrosion is on the outside of the strainer. It cannot be blamed on another boat. There's either salt water leaking somewhere or as someone mentioned, battery fumes. I had a strainer that did that (not so severe) and it turned out the plastic cover was cracked and seawater was seeping through the crack and keeping the bronze wet.

I don't know how a grinder could get the corrosion off in the nooks and crannies. I would think of sandblasting if possible.
__________________

__________________
rwidman is offline   Reply With Quote
Reply

Tags
corrosion, water

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 19:55.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.