Toe Rail Corroding a little.

[Hoohaa]

My 40ft Fglass Yacht has an aluminum toe rail, as do most. The boat is 28 years old.
At a few points around the rail there has been some corrosion. It seems to be accruing where water may be sitting on the deck, near the drains, not a big deal at the moments but I was thinking it might be a good idea to put some sacrificial anodes onto the rail.
Does anyone have experience with this sought of problem?
Note that the boat is on a swing mooring and obviously not hooked up to shore power.

This is a general shot showing what the toe rail looks like. Unfortunately I don't have a shot of the corrosion yet.

[Stumble]

It sounds like poultice corrosion, which occurs when standing water is in contact with bare aluminium, typically because of a fabric, dirt, or other much holds the water there. But it is also pretty common in the bottom of fuel tanks, and as you have discovered in places where water collects.

There really isn't much you can do, and anodes won't help at all. This is a chemical attack, not an electrical one. The only thing you can really do is to try and ballast the boat so the water drains, add new weep holes, have the entire toe rail re-anodized, or replace it with a freshly anodized rail.

There are some spot anodizers available, but I have no experience with them, and can't comment on how they would work, or the problems with using them. A local machine shop may be able to privide some insight however.

[noelex 77]

One of the big problems with aluminium toe rails is that there are often large amounts of SS attached to a small amount of aluminium. With some moisture it leads to the potential for galvanic corrosion which I think is the most probable cause.
Poultice corrosion is a form of crevice corrosion and requires an absence of oxygen. This is not commonly seen in this situation as the water will provide plenty of oxygen, but it is a possibility as Greg says if there is a lot of dirt accumulation, creating an oxygen free layer.

The solution to two above causes of corrosion are very different, so some more pictures would help in making a more definitive diagnosis and suggesting a remedy.

[SurferShane]

Maybe time for replacement with stainless or rubber?

[Hoohaa]

I will post some pics but will not be onboard until next Friday.
Thanks for the coments. I do have slight drainage issues around the rail so may have to look at making some extra drain holes where its needed.
Thanks for the advice.
SurferShane
I shudder to think what replacing it would cost? Would another option be to grind it out and then use a mig welder to build it back up?

[Jim Cate]

Originally Posted by Hoohaa

I will post some pics but will not be onboard until next Friday.
Thanks for the coments. I do have slight drainage issues around the rail so may have to look at making some extra drain holes where its needed.
Thanks for the advice.
SurferShane
I shudder to think what replacing it would cost? Would another option be to grind it out and then use a mig welder to build it back up?

Welding in situ might be pretty hard on the f/g under it!

Without seeing the extent of the damage it's hard to say, but I had similar issues on our previous boat. The damage was cosmetic, so I filled and faired with epoxy and some sort of thickener (don't remember), then found some paint that simulated the kinda tarnished anodizing and it didn't look too bad. Had to remember not to put a shackle or snatch block on those spots, tho'!

Cheers,

Jim

[Stumble]

Figure replacing a side would run about $30/running foot. Plus the installation costs. But it has been a while since I looked at buying toe rail extrusions.

A welded repair really requires the existing rail to be removed, because welding that close to fiberglass is a very tricky problem, and one slip of the welder and now you have crystallized fiberglass that has to be cut out and repaired. Once you remove it, you might as well just re-anodize it. The hard work has already been done.

Frankly the other option is to just leave it. If it is poltice corrosion, it doesn't really spread beyond the localized area where the water is collecting, so other than the fact it looks rough, it won't really do much damage to the rest of the boat.

If the corrosion is more than just superficial and is significantly weakening the structure of the rail, you may be able to remove it , and weld in a splice of fresh aluminium where the damaged section already is.

[Hoohaa]

I am shore it’s not structural. If it’s not likely to spread then I will probably leave it or use a filer on it? .
Regarding the costs of replacing it. Fondly enough I do know what it cost to replace about 3m of toe rail on a 1 week old Hanze 35. $2065 if I remember correctly. But that’s another embarrassing story.

[delmarrey]

These are 30 YO toerails. And this is what happens to them once they loose their coating and have SS screws holding them down. I had to grind the heads off and drive them thru. Some spots I could see day light thru. I ended up sealing the hull to deck joint and putting a cap rail over that. Now the boat is better then new.

See my blog......

.

[GordMay]

Thread a chamois, or other absorbent rag, through the slots (leading overboard) of the toe rail, at the locations where water accumulates on the deck. This helps wick the standing water overboard.

[Hoohaa]

Got a rough pic of the toe rail yesterday. Sorry about the quality.

[Blue Stocking]

Originally Posted by GordMay

Thread a chamois, or other absorbent rag, through the slots (leading overboard) of the toe rail, at the locations where water accumulates on the deck. This helps wick the standing water overboard.

KIS
Blue's drains are inboard of the teak toerail, and trap a small amount on water.
Wrapped a piece of chamois around a 2 oz fishing weight, layed it in the wet spot, --and problem solved.

[Stumble]

Hoohaa,

I don't see anything there that looks like something I would even worry about. The weight idea is great to prevent more damage, but that's as far as I would take it.

[Hoohaa]

Thought I would update this post.
The corrosion is getting a little worse in some places. I was wondering if I could attach some anodes to it and if so, what type of anode would it need to be?

Jeff

[boatman61]

I had that problem a few years back.. only happened when wet.. turned out I had a crack in the coating on the live wire to the nav lights on the pulpit and current was leeching every time water drops created the link.. rain, waves and the like.. check for stray current.