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Author Topic:   Rail stanchions,rust stains & closed cell corrosion
Alan Hiccock posted 02-17-2002 08:32 PM ET (US)   Profile for Alan Hiccock   Send Email to Alan Hiccock  
After inspecting my new '88 Whaler sport the only thing I found that raised a red flag was rust stains around some of the side rail stanchions. These rust stains and slightly rusted bases are a sure sign of water ingress and closed cell corroision. Ive got a couple questions..
Has anyone gone through the process rebedding these rail stanchions & how did they go about doing it?
Also how serious is this? The rails are secured very well it seems & only 50% or so show a rusty discoleration on the fiberglass & stanchions , wondering if I should do this ASAP or later this season, next year.
Thanks in advance for any help on this subject. Alan
flwhaler posted 02-18-2002 08:24 PM ET (US)     Profile for flwhaler  Send Email to flwhaler     
Are you talking about totaly removing them from the boat to clean the stains?


Alan Hiccock posted 02-18-2002 09:18 PM ET (US)     Profile for Alan Hiccock  Send Email to Alan Hiccock     
Hi Michael,
The stains dont bother me as much as what they represent, its the moisture that got in there that caused the screws to rust hence creating rust stains around the fiberglass area and on the side rail stanchions {bases} themselves.
Its only about 6 out of 24 stanchions that show rust but I'm going to rebed all of them. I tryed to remove a screw today on the rustiest one and the screw broke off leaving most of it inside so I'll have to extract it or drill it out.
What I wasnt sure is if I should use thickened epoxy paste or 5200 but I think the 5200 is best because it offeres flex which is needed when bedding hardware so Ive learned.
I also learned the rebedding of the rail base's is pretty straight foward, let the holes dry out , drill em a little clean them up.Apply the 5200 inside the holes & on the bases, screw them till they make contact with the boat but dont tighten them. Let dry couple days then tighten them & trim excess 5200 away .
Thanks for chiming in,
lhg posted 02-18-2002 10:11 PM ET (US)     Profile for lhg    
There is other discussion on this task, but I don't think yours is the way to do it.

First of all, remove the whole side rail, clean the bases of rust, even by wet sanding with #1500 if necessry, or replace bad bases.

Drill out bad, waterlogged or stripped holes with a drill twice the diameter of the screw threads, going all the way through the underlying plywood pad. Let air dry for a day or so. Then fill the holes with white Marine Tex or other repair material, either polyester or epoxy based, sand flush and re-buff up the surrounding area getting rid of rust staining, then re-drill the holes for new SS screws to install the rail. Will be like new, and the rail base will cover the white screw patch. Forget using the 5200, as it is bonding agent, not a caulking compound.

Alan Hiccock posted 02-19-2002 09:55 AM ET (US)     Profile for Alan Hiccock  Send Email to Alan Hiccock     
Yesterday I bought 2 different sized stainless screws incase I did decide to go bigger. Did you ever try to drill into stainless/brass hardware such as these bases, hmmmm ..can be done but wont be easy.
Ive got the epoxy paste, what I was thinking last night is using epoxy in the holes { or marine text, worked with that too}
then the 5200 every where else.
thanks for the reply,
Tom W Clark posted 02-20-2002 12:31 AM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
Whoa! Let's back up a bit. First of all I suspect the rust staining you are seeing is actually crevice corrosion, a slightly different chemical process related to stainless steel hardware. It is indicative of stainless hardware that is dirty. Usually cleans up with a good scouring and/or polish.

To remove the stains I recommend removing all the rail hardware and having at the stains. Polish up the rails while you are at it.

Now, if I'm wrong, and the screws are genuinely rusted, then I would have to suspect someone (not Whaler) put non-stainless screws in there.

You said one of the screws broke off?! I can only imagine that happening on one stanchion base and that would be the one at the bow. This one stanchion base is attached with machine screws tapped into a piece of aluminum molded into the hull instead of sheet metal screws screwed into the wood backing.

I cannot imagine a screw would break off if it's screwed into the wood backing in the hull. If it did it would indicate the wood is especially good, not rotten!

If you can get a grip with all the screws and none are stripped, then DO NOT drill them out at all! Simply reinstall them with 5200. The idea of "drill em a little clean them up" will only make matters worse.

If you have some screws that are stripped then you will have to adopt a technique like lhg's. I would use 5 minute epoxy or Marine-Tex (epoxy putty) without drilling the holes oversize unless the wood backing is really mush.

If you use oversize screws in an attempt to achieve more grip you are going to have a mess on your hands. Increasing the size of the countersink is going to be near impossible to do cleanly. You could (maybe) use pan head screws and cover the countersink in the hardware but it will not look very good, it will look like a quick fix.

jameso posted 02-20-2002 09:04 AM ET (US)     Profile for jameso  Send Email to jameso     
I agree with Tom, had the same problem on my 15 and I have seen it on other boats. If the heads of the screws aren't corroded I would not be too concerned. The stanctions are chrome plated and I am sure that some interaction between the stainless and the chrome occurs over time. I used BarKeepers on my bases and let it go. I did find one screw on the stern light bracket that was not stainless, drilled it out and replaced.
Jim Armstrong
triblet posted 02-20-2002 10:25 AM ET (US)     Profile for triblet  Send Email to triblet     
One falacy in Alan's plan is the wait a day and
tighten. With 5200, I doubt you'll be able to
tighten them after it sets.


Alan Hiccock posted 02-20-2002 10:26 AM ET (US)     Profile for Alan Hiccock  Send Email to Alan Hiccock     
Its only 4 stanchions out of 24 and all on port side. 2 screw heads broke off while removing them & yes these are ss screws. These are the side rails on a 15, they really get a work out, the way I figure it, much more then bow or stearn rails & if these screws arent tightened up couple times a season then moisture gets in there enough to corrode the screws and stain the fglass & base which is what happened here.
Im no pro but I've learned this is called " closed cell corrision" Another thing I learned is stainless steel does rust, its not " stainproof" steel.
I got this stuff from David Pascoe's site,
Thanks to all for chiming in, Alan
Tom W Clark posted 02-20-2002 11:24 AM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
"Closed cell corrosion" in another name for crevice corrosion and one that I had not heard of before. It seems to be a term that David Pascoe has coined to refer to crevice corrosion in the context of a cored hull.

OK, so the crews broke off. I think that's a good indication that the wood is not so bad. Go ahead and clean it all up and reinstall with 5200. I agree with Chuck that you should not wait a couple of days and then tighten them up, but for different reasons.

If you wait then the tightening of the screws will break the bond you've worked hard to achieve. Best to tighten them up the first time around and let it be.

Chuck, next to Sika 1A, 3M 5200 is the strongest retail level polyurethane sealant I have ever used, but it is not strong enough to prevent a screw or bolt from being undone. We seem to keep contradicting each other on this important point. I will send you a piece of CSW with screws bedded in it and you can see if you can get them out.

Alan Hiccock posted 02-20-2002 01:08 PM ET (US)     Profile for Alan Hiccock  Send Email to Alan Hiccock     
Tom, I like the tip on applying the 5200 and bolting her right on there thus letting the whole thing set up & dry solid. . Im all ready to reattach the rail everything is cleaned up, got new ss screws, the holes are air drying , it all looks good, tommorow I'll stick these things back on if the weathers right. I'll have to read the 5200 tube, forgot if it can be used around 50 degs. or not.. Thanks for all the help.
lhg posted 02-22-2002 02:06 AM ET (US)     Profile for lhg    
I still say I've never heard of setting rail bases in 5200. Is for adhesive bonding purposes, or caulking purposes? Can the rail be removed at a later date for future repairs to both hull and rail?
Tom W Clark posted 02-22-2002 02:10 AM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     

Yes, the rail can be removed later. See my post in the 5200/4200 storage thread.

Alan Hiccock posted 02-22-2002 10:00 AM ET (US)     Profile for Alan Hiccock  Send Email to Alan Hiccock     
The 5200 is needed because the new screws dont bite as well as the orig. also it forms a gasket to keep moisture out.
I like the way it came out, no more rust stains but more importantly all new ss screws and properly bedded side rail .
I just replaced the screws on the starboard side. LOOKING GOOD!
thanks for the replys,

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