Bubbly salt(?) deposit

RichB · 03-21-2011, 05:34 PM

Hi Chaps

Just spent the weekend giving the old girl a rub down to spruce her up after the winter - guess many of us are doing similar things about now!

Noticed on the base of the drivers/nav seats a lot of what I can only really describe as bubbly salt deposit, mostly in the area at the very edges of the metal plinth. I also found that the metal undersides/mechanism of the seat had a similar deposit.

The closest thing I can imagine to what it looks like is a leaked battery in a torch (or more expensive equipment!).

Can someone put my mind at rest, tell me it's all perfectly normal and just how sea salt goes - just rub it off with a bit of soapy water...?

Cheers all.

***mikeyt*** · 03-21-2011, 08:42 PM

Normally i would suggest that it's a process of electrolysis happening (& it may be if you have power seats) caused by battery leakage but i suspect you are correct in that it may simply be the salt water reacting with some bare metal over a period of time. I would suggest cleaning her up & giving it a touch of paint protection.

RichB · 03-24-2011, 06:06 PM

Hi Mikey - thanks for the reply. I cleaned up one side a bit, left the other (ran out of time!) so might try taking some photos for curiosity sake. Both seats quite a way from electrics as far as I can tell - manual seats.
If I remember right, the bubbling seems to come mostly from near the floor bolts. Could it be a reaction between 2 metals there?

RichB · 03-28-2011, 01:56 PM

Here is a photo of what I mean. Not great, would like to blame the camera, but I think I'm just not a great artist...

SaltPedestal by bennett_rg, on Flickr

***mikeyt*** · 03-28-2011, 03:35 PM

It definitely looks like salt deposits but i have to admit i'm a fresh water boater & haven't dealt with this issue. There is an aluminum plate under the floor that the seat bolts are threaded into.There may be a dissimilar metals issue that is causing the problem along with the salt air/water. Maybe some of our saltwater based members can chime in here.

Zackattack · 03-28-2011, 04:16 PM

I dont think I am the expert here, although I have had several previous boats that I actually moored constantly in salt water(some in a boat house, one outside slip) and with that came a constant effort to keep the salt water and air from attacking the entire machine.

This does look like it is just a simple salt air attack on the metal. Whenever the salty air has the chance to work its magic on Aluminum, or any metal for that matter, that is not protected it will come up with corrosion that looks like this. Just clean it well and then protect. If left long enough I have even seen Stainless look like this. Make sure you always use a protectant on these metals. Anything that will not leave the metal exposed to the sea air. I would visit my boat weekly and do a constant ship shape routine and washdown and was always able to keep up. But if unattended the salt air goes on attack.

I do not think you have any electrolosis issues or anything actually wrong at all, just needs cleaned and protected. You can even use wd40 if thats all you have. But you can go to the marine supply and get a nice 3m spray for metals too.

Electrolosis is a nasty word, it will eat your engine and outdrive alive! You have Zinc plates usually all over the outdrive in order for these to be the sacrificial anode. The Zinc is a type of metal that will take the attack first and then the outdrive is safe. So always make sure your Zincs are fresh and new looking. Once they are showing ANY wear- REPLACE. This is the cheapest insurance you will ever buy.

Electrolosis can also be a reslut of actual electricity either dc or ac from other boats in the water or your own. But the results of it is usually the metal actually being eaten away and gone, not a growth like this. At least from what I have seen.

Again, I am not an expert. But I throw these 2 cents in. All comes down to clean and coat your boat.

By the way, what is your location? Are you on the Salt Water? Is the boat actually used in the Salt Water? Do you store the boat near Salt Water?

RichB · 03-28-2011, 05:21 PM

Thanks - on the river now, but was out by sea for a few months, and had a couple of salty baths last year.

Figured it was cleaned down well last year, guess not!

Thanks for the help chaps

sanukc · 04-05-2011, 08:21 PM

Rich,
This is a very interesting topic. I was cleaning down our boat and saw some of these deposits in the cuddy cabin. I was not sure where they came from. I saw them only around the screws on the aluminum frames of the in-cabin storage compartments.
Attached are a couple of pics.
I was going to go over them with a wire brush and see if I can clean up that area. But where I found them, there were no wires there either.

Attachment 2921

Attachment 2922

sanukc · 04-05-2011, 09:06 PM

As luck would have it, the company I work for has a subsidiary in the marine closure business specializing in aluminum and stainless closures. I talked to the chief engineer and the senior fabricator there and they said that this is corrosion happening in the aluminum, primarily due to the use of dissimilar metals touching (aluminum and the steel screws holding it down).
To prevent it in the future (and to clean up my current issue), they recommended:
- remove the screws (possibly one-by-one),
- clean the area with a ScotchBrite pad,
- apply something like Tef-Gel (LED lighting, soundproof, Sailor's Solutions Inc.) to the screw
- put a nylon washer in before screwing it down again

Although, based on their experience, if the corrosion is deep, apparently I can only hope to prevent more in the future by following the above steps. It does not repair the damage already done.

Zackattack · 04-05-2011, 10:28 PM

Welcome to coastal conditions! Nice report though Sanukc. I doubt it would ever happen at Lake Powell though! Moisture, and especially salty air will enhance it for sure.

Bubbly salt(?) deposit

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