• Untitled Document

    Join us on March 29rd, 7pm EST

    for the CBEC Virtual Meeting

    All EYO members and followers are welcome to join the fun and get to know the guest speaker!

    See the link below for login credentials and join us!

    March Meeting Info

    (dismiss this notice by hitting 'X', upper right)

Raw water strainer / impeller housing - what kind of corrosion am I looking at

Geoff W.

Makes Up For It With Enthusiasm
Blogs Author
IMG_20190410_164000.jpg
IMG_20190410_164041.jpg
IMG_20190410_164109.jpg

I'm not sure I ever actually noticed the raw water strainer's color before, but today as I was changing my first impeller I noticed that the housing for the strainer is QUITE green/blue and corrodey, and the housing that the impeller pump is sitting on looks like it's got some green on it, too. Is this galvanic corrosion? Or leaky saltwater somewhere? My zincs are fresh as of last November (including the heat exchanger) so I can't tell if this happened a while ago or is still happening.

Any recommendations on further diagnostics to quiet a worried mind? I do sometimes notice a tiny bit of water in the engine compartment underneath the raw water strainer, so it could either be seeping out of there, or from somewhere else - it's sort of a low point that a lot of different water runs could end up in.
 

Christian Williams

E381 - Los Angeles
Senior Moderator
Blogs Author
Diagnosis: patina. I had to pay extra to have them put that on the bronze bust of myself in the living room.

You can scrub it off if you like.

It's oxidation. Maybe even protects from more of itself. Our metallurgists will know more.
 
L

Leslie Newman

Guest
I don't like seeing that much patina. There are several methods to clean bronze. Eco friendly ways.
I Googled and came up with -
To remove patina, rinse the bronze item in warm, distilled water and gently clean it with a toothbrush. Make a paste from either baking soda mixed with lemon juice or equal parts of flour and salt mixed with plain, white vinegar. Gently rub the paste onto thebronze and leave it for about 20 minutes.I always remove mine and clean it good each season.
My theory is be good to my boat and she will be good to me.

Strainer1.jpg

Strainer2.jpg
 

Geoff W.

Makes Up For It With Enthusiasm
Blogs Author
Ok, so I won't worry about this one, then. Plenty of other stuff to furrow my brow at.
 

toddster

Curator of Broken Parts
Blogs Author
So, bronze is an alloy of copper, tin, and sometimes other things, notably manganese for high-strength parts like your propeller. It's always going to corrode some in a saltwater environment. General rule of thumb as I've heard it is green (copper oxides) patina OK within reason, pink patina (manganese oxides), not OK. Pink means the part is getting brittle.
 
L

Leslie Newman

Guest
You are always trying to balance working on the boat and using the boat. When it comes to all the systems, I want them as good as possible. And I have found over the years that a nice clean part is much easier to service. And tell if something is going wrong with it. If your engine is a mess you aren't as likely to spot something leaking as quickly as when you keep your engine and engine compartment nice and clean.
There is patina and then there is something that looks more than patina. If it starts looking like more I do a cleaning.
Every captain manages his boat how they see fit of course.
 

Kenneth K

1985 32-3, Puget Sound
Blogs Author
If your engine is a mess you aren't as likely to spot something leaking as quickly as when you keep your engine and engine compartment nice and clean.

Actually, Leslie makes a good point. There is an overall patina that may develop over time due to exposure in a marine environment, but there are also raw water leaks (impeller cover plate gasket, internal pump seals, etc) that will cause the same discoloration in "streaks" where the leaks are running off.

But, you can't see the latter if you have too much of the former.
 
L

Leslie Newman

Guest
Do you do anything to keep the cabin humidity level down in the winter?

I've had five different boats over the past 35 years. Never did any special de-humidification, but they all had the constant turning solar vent fan installed so they had air moving through the cabin.
Current boat has a vent installed in one of the companionway boards and then in the forward hatch is one of those solar powered/battery backed fans. Seems to keep the boat humidity in check fairly good.
Plus I visit the boat a few times in the winter just to check on things. I did need to wipe down the wood a little this past winter once. I would probably run something to dehumidify but I don't keep power to the boat when it is on the hard all winter. We do remove the cushions for the winter and take them home. If you don't take them home, turn them on end. Have sort of a winterization drill.
 
Last edited by a moderator:
Top