Question on re-bedding swim step hardware

[Gin]

Several forum members have dealt with rust issues on their swim step hardware by re-bedding with butyl tape, following the technique described on Marine How To. One of the recommendations on that site is to not put any butyl or other sealant on the underside of the hardware, below deck. That makes total sense for something like cleats, where the cleat is above deck and the attachment is inside or under a gunnel.

But what about the swim step, which is often awash, and gets a lot of water on both sides of the fittings and the hardware? I'm unsure on what I should do on the underside.

Gini

 

[Red Raven]

Gini,

I think both sides makes sense in this instance as both sides are subject to water intrusion. If you do this while hauled out it would be much easier and would allow you to let the swim step core drain and dry if it is wet. When I added an additional rail post to my swim step water came out after drilling the hole! Not good! The boat was in the garage so I was able to let it dry out before sealing and bedding the bolts, both top and bottom.

Curt

 

[Gin]

Thanks Curt. The boat is on the hard now. Have kept the screw holes dry. Wish I could dry them out longer. I fear moisture has been in some for awhile. But hoping for net improvement.

Gini

 

[Hydraulicjump]

Gini,

There is a simpler solution I learned from Andrew Custis. Actually, I watched him do it and was intrigued at how well it worked.

Strong acid reverses the ferrous (+2) to ferric (+3) oxidation process. All those iron stains (we have the same on our swimstep) are just oxidation of the stain-less steel (meaning stainless steel just stains less), probably deposited as ferric hydroxide. Once in the ferric state (+3) iron is basically insoluble and stains everything. And due to the light absorption/reflection properties of iron in the ferric state, a little bit makes a bright red stain. There is iron on Mars, but a little bit goes a long way to making it the red planet.

Strong acid reverses this by reducing the oxidation state of the iron to Fe (2+) which is highly soluble (meaning the water can hold a lot of iron in it if it is in the 2+ oxidation state). It literally dissolves.

So I got some On & Off, which I am pretty sure is just an oxalic acid solution, and put some in a plastic bucket and then painted the stain with a cheap paint brush. If I remember my chemistry right, the low pH (high H+ concentrations) reduces the iron (adds an electron) and the oxalic acid acts as a chelating agent, pulling all that iron into solution and binding it with an organic molecule. When you turn a hose on it it washes away. Since oxalic acid concentrations are so low once you dilute it with the hose--especially if you wash it into the high pH seawater--it causes no problems.

The only problem that I discovered the hard way is that you do NOT want to get it on your clothes and for sure wear gloves and goggles while putting it on. Also, use lots of water to wash it off once the stain fades.

This approach is easy and a whole lot less complicated than rebedding something. Do it once or twice a year and you'll be good. I can't guarantee that this will get rid of all rust stains (I have a couple on the mast that seem too tough to get rid of), but it seems to get rid of the ones that land on fiberglass. Of course, this is hard on any wax you might have.

Just offering a short cut. And based on your background, I am pretty sure you know all this. Just be careful with this stuff.

Jeff

 

[BB marine]

This approach is easy and a whole lot less complicated than rebedding something. Do it once or twice a year and you'll be good. I can't guarantee that this will get rid of all rust stains (I have a couple on the mast that seem too tough to get rid of), but it seems to get rid of the ones that land on fiberglass. Of course, this is hard on any wax you might have.

This is a great approach for removing the stains. The key component is trying to eliminate the ones that are caused from water intrusion. If the stains are coming from under the hardware this is telling you that it is not sealed properly. If it is not bedded properly the results will be what Curt experienced. Water in the platform. The way the water gets into the platform is though penetrations that are not sealed properly. When you see stains (rust) coming from under a fastened component that is telling you water has penetrated under it and it is not sealed properly. If you see the rust on the outside surfaces it can usually be wiped and polished. 304 SS has enough carbon in it that it will leach and show rust staining.

A fellow Cutwater owner showed me his 2016 C28 swim platform that he had to replace last year. The platform was rotted and came loose from the transom. When he removed all the hardware he found little to no sealant used. He had rust stains at every penetration location. Most of the SS screws were not usable because of corrosion. He replaced all fasteners with 316SS and most of the hardware with 316. He also bedded all hardware. This project is a PIA but may be worth the trouble down the line. It is a boat that sits in the water Resealing hardware is a part of boat maintenance.

To answer the question I use Life seal polysulfide for bedding it is above or below the waterline use.

 

[Gin]

Good info from all. I used a combination of the suggestions here -- On and Off to remove rust stains, and removal, cleaning, and rebedding of most of the hardware in the hopes of preventing future stains.

The On and Off worked super well to remove stains from the fiberglass. For the stainless steel hardware, I used a citric acid product to clean up any rust. I also replaced the washers. What was on there appeared to be 18-8. I got 316 stainless steel washers from McMaster-Carr (surprisingly reasonable in price; worth not having to clean up the old ones).

There is some rust bleeding from under the flat SS bars that support the swim step, and on the through bolts to them. For now, On and Off is all I'm going to use on those areas. I'll see if it is there again next year.

After cleaning things up, I'm putting the hardware back on using butyl caulk tape for rebedding. After so many positives about that product, I decided to go with it instead of a polysulfide. The polysulfide, well applied, would have worked as well, I'm sure (if Brian uses it, it must work well). Per the suggestions here, I'm caulking both topsides and undersides.

In the FWIW category, there is a good-looking older R25 also in the boatyard. I believe it may be owned by someone who works there. It has new bottom paint and the entire boat has been buffed and waxed. Looks sharp! But, underneath the swim step, the rust staining is extensive. I was feeling ambivalent about whether to go to the hassle of removing and rebedding my hardware. But after seeing the underside of the swim step on that boat, I decided to dive in.

Almost done getting everything back on. As always, past posts and the suggestions added in this thread are hugely helpful. Thanks everyone!

Gini

 

[SkookumR29]

Below are some additional thoughts on this topic that I posted back in February on another related string.


Something that needs to be understood and remembered when dealing with this problem.....

Stainless steel is very resistant to corrosion in both fresh and salt water environments because when it is exposed to an ample supply of oxygen, it develops a natural oxide layer and is then referred to as "passivated". But, when the surface of the stainless steel is deprived of oxygen, it becomes "active" and makes it very vulnerable to corrosion - the oxide layer doesn't have a chance to form. This is very common where fasteners and railings penetrate the boat deck surface and even where moisture is trapped under fender washers and the like. The same happens to underwater stainless where again, it does not get a good supply of oxygen - but to a lesser degree.

BB is correct in that the key to minimizing the problem is good bedding and sealing. You can clean all you want, but until you solve other issues, the stains will just keep coming back. I recently removed all of our swim step railings and Weaver davits, cleaned everything up and re-bedded/sealed everything when I reassembled. I anticipate that things will look good for a few years, but inevitably I'll be doing it again. Some of the old thru-bolts showed definite signs of corrosion where they passed through the swim step structure.

 

[Gin]

Jerry, yes, I had read that related thread you reference. It was a significant factor in my decision to actually remove and re-bed the hardware in an effort to minimize the issue. Thanks for that post, and for refreshing the info in this thread for anyone who is new to the concern and wanting to bone up on it.

Gini

 

[dbsea]

Resurfacing this thread as my boat is currently on the hard for ceramic coating and some other projects. One of those other projects was installing a Garhauer crane on the swimstep for my outboard motor. When we drilled through the swim platform, water came out two of the holes and the drill bit was gunked up with wet plywood. Not ideal. It sounds like from reading this thread, I'm suffering from the same improper sealing of through fittings on my swim platform that others have noticed. There is excessive staining under the fittings where the swim platform struts attach to the platform, and where the platform bolts to the transom, which tells me that they were not properly sealed. How dire is this situation, and can I wait until the fall at this point? Boat is 6 years old. What is the proper remedy for the wet swim platform core?

Photo of underside of swim platform:

https://1drv.ms/u/s!An3QgiOrn39pqGwY1cA ... y?e=xZQ1hj

 

[BB marine]

Yours does not look much different than any other ranger or Cutwate have seen. The wood is probably a bit soggy and needs to be dried out. It will need attention sooner or later. The longer the more damage. It is hard to tell how wet the platform is from the pictures. I saw C28 that was bad enough that it needed to be replaced and was.The new platform was from Fluid Motion. It was a 2016 and by 2018 was falling apart and loose from the transom. Yours doesn't look as bad as his did. I would suggest having some backing plates made for the weaver davits . That is if you use them. Using 1/4 -20 bolts washers and nuts will eventually crack the thin fiberglass layer on the bottom side of the platform. Installing a stainless steal plate the same size has the weaver mounting plate on the bottom side will add the correct support and reduce the chance of the underside cracking. Just a suggestion!

 

[dbsea]

Thank you, Brian, I really appreciate all of your inputs on this forum. I will tackle this project in the fall, after this season. The boat splashes in 2 hours so it's a bit late for this haul out... Plus with the ceramic and all the other work, my wallet is feeling a little light at the moment! :-D

 

[Kimberly Dawn]

This a great post, and very timely!

Along with many others who are waiting to receive their new boat off the production line, this is an eye-opening topic. I intend to utilize my swimstep to support a rather heavy dinghy/davit configuration.

Although it would be nice to think FM would monitor posts like these and discuss at their weekly QC meetings for changes to their production process, i will make plans to disassemble my new swimstep to reseal all penetrations and change out fasteners as necessary. As they say, "an ounce of prevention is worth a pound of cure."

Bob
Kimberly Dawn

Sidebar: some of you guys (gals) are scary smart!