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Rusted Stainless!

Questions and Improvements on Key West Boats Hulls, Parts, Hardware and Structural Components

Rusted Stainless!

PostPosted by Tom Marlowe » Fri Feb 10, 2012 11:39 am

It happens now and then. An owner has an issue with rust on his stainless. It's more common on new boats than on older boats and the natural assumption is that the stainless is low quality. This isn't really the explanation though. Of course the consumer would expect the builder to deny low quality but a little known fact is that many of the major builders have formed a buying group to obtain common items in large bulk numbers to increase their negotiating power with suppliers. Stainless fasteners and other hardware are often very common items not unique to any brand which makes it a good plan. Because of this the screws, for instance, that go into a Key West Boat in production came from the same source as the screws that go into many other brands; some of them costing thousands of dollars more. There simply is no difference in the quality of either brands fasteners, so what makes them rust? It's a good question so let's see if we can come to a better understanding of the nature of SS itself, what allows it to rust, and how to help prevent it.

A good starting point is to understand the material. There are different grades of SS used in different applications. What is ordered specifically for Key West Boats is 316 or better in guaranteed quality. Guaranteed quality is a relatively new term to me. What it means literally is that if you simply order 316 grade then you might get 316, but if you order guaranteed quality then the supplier has more skin in the game, so to speak and the builder can go back to them with issues, and of course it costs more. Bottom line it's supposed to be tested before delivery. So, if it's so good and guaranteed quality how can it rust? Recommended reading at this point is the article at this link. ... 71201a.htm

Wickipedia also has a very good similar article if you'd like to read more, but the consensus is that stainless is a steel that stains less than more ferrous materials, but certainly can rust under some conditions. Salt water is a catalyst of course, but in my experience it's not the primary culprit. More often I've been able to trace the cause back to the fresh water the boat is washed with. That sounds all wrong doesn't it? But remember this; fresh water comes from many sources and some of it is heavy with minerals. Most of us have seen a driveway or sidewalk with stains from a sprinkler system. Those stains are from the minerals in the water. The same thing can happen to the SS on your boat if your fresh water has minerals in it. The water dries up leaving the residue, and then the salt water does its thing causing the deposits to oxidize.

If you take the time to read the referenced articles you will come to understand how SS actually forms a protective layer over time which is key to rust resistance. This explains to me how the new boats are more prone to rust than older boats. The SS has had time to age and form that barrier. It may be a good idea to install a filter in line for the water you use to wash the boat, especially if it is well water. It's also a good idea to dry the stainless after washing and probably even to apply a wax or spray metal protectant of your choice.

If you have SS that is already rusted the first step is to clean it up of course. An abrasive cleaner is obviously not a good idea. One of the best cleaners I've found for this purpose is OBCO Pro Creme, available at OBCO chemical corporation, Charleston SC, phone 843 572 6688. Follow the directions on the bottle and the stuff works good with a little rubbing. It even helps to get the stains out of the fiberglass.

One story I like to tell regarding stainless ; a couple of years ago we had a boat ready to ship but it had some stains in the floor. We used a harsh chemical, I suspect, to clean those stains. The result was that every piece of stainless in that boat was tarnished and or rusty within days. It was shoved aside and another boat was shipped in its place. A few months passed before we got back to that boat, but when we did every piece of hardware in the boat looked fine. Nothing needed to be replaced, and no one had touched it. I wouldn't tell this story if it were second hand information. I witnessed this myself and it was proof to me of the chemical process stainless steel undergoes. Pretty cool stuff.

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Re: Rusted Stainless!

PostPosted by JMB » Sat Feb 11, 2012 11:01 am

Thanks for the tutorial.


I use Flitz to remove rust stains and to polish metal, plexiglas, curtain windows, etc. The stuff works great and is not harsh. I am amazed how well it works for being just a paste. It is pricey though! But it doesnt take much and seems to go a long way.

Some of the members here may be able to use some of this.

I have no affiliation with this ( or any other ) company. So this is my honest experience. It works!
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Re: Rusted Stainless!

PostPosted by kellf190 » Wed Apr 11, 2012 2:44 pm

I have a 176 DC which is about 3 -4 years old. Two years ago I was getting a lot of rust on the edges of the dash board. The metal dash board has a clear film on it and I found water was getting under the edge of this clear film. I used a razor blade to trim it back and found the metal was hardly rusted at all and only slightly stained. Once I could get to the metal itself the stains came off easily. I suspect eventually I will end up removing all the clear film entirely.
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Re: Rusted Stainless!

PostPosted by buckmasterisdon » Mon Feb 25, 2013 10:11 pm

I just bought a 2006 268 CC and I'm thrilled to have it :D I spent a little time going over it after picking it up last week and found much rust around the edges of the dash board. I'll try the cleaning recommendations and removing the plastic wrapping, it it's still there, and hope it improves the looks before the spring fishing season. If the cleaning doesn't work does anyone know how I can order another dash board? Thanks much and looking forward to using my new Key West, oh, and this forum too ;)
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Re: Rusted Stainless!

PostPosted by Florida Speckman » Sun Jun 07, 2015 1:43 pm

There is a product called Goof Off Rust Stain Remover available at Home Depot. I use it to remove rust stains from just about anything. It is made for wood ,concrete ,fiberglass boat decks, vinyl siding, brick, stucco and painted surfaces. It is hydrofluoric acid and oxalic acid. One place I use it is to remove the brown stains at the water line on my 1720. It does remove the wax so you need to put a good wax back on. You just spray it on with a garden sprayer and the stain disappears and then rinse with water. Make sure you wet your trailer before you use it.
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Re: Rusted Stainless!

PostPosted by laidback3 » Fri Feb 19, 2016 12:15 am

I thought this might be good to add to the thread. I use softscrub with bleach or dawn to clean the floor but stick to bar keepers friend for the stainless. 303 is great to wipe down the hull in between waxes.

WARNING: Your Stainless Steel can be damaged by exposure to acids and other corrosive agents found in many cleaning products. A partial list of additives that may cause staining and a weakening of the finish are provided below. Use of these and other similar solutions to clean your boat can cause your Stainless Steel to bleed and will void your warranty.
Chlorsulphonic Acid
Ferrous Iodide
Hydrobromic Acid
Sodium Chlorite
Sulphur Chloride
Bleach Comet
EZ-ON, EZ-OFF Cleaner
Ferric Chloride
Hydrofluoailicic Acid
Silver Chloride
Sodium Hypochlorite Sulphuric Acid
Muriatic Acid
On & Off Cleaner
Rust StainsAway
Ferrous Chloride
Hydrocloric Acid
Hydroflouric Acid Sodium Biflouride
Stannic Chloride
Soft Scrub
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Re: Rusted Stainless!

PostPosted by Redfish Nation » Wed Mar 16, 2016 11:01 am

Thank you for posting this topic/article! Very good read and informative.

I'm curious to know if the SS bolts/screws/parts begin to rust, then are they able to be cleaned and restored? Or should I just attempt to order new parts?

I have a 18'6 Bay Reef with a center console, and there are one or two bolts/screws that have begin to show signs of rust. I do not use any chemicals to wash my boat down. I only use water, a deck scrub, and a low-end pressure wash.

Are you saying that SS will heal itself and redevelop its own coating after the rust is removed? If so, then I had no idea.
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Re: Rusted Stainless!

PostPosted by windy city » Wed Mar 16, 2016 12:26 pm

Just an FYI, I fabricate stainless steel, among many other metals. "Rust" on stainless is not typically the same as rust on mild steel products. It is not usually structurally damaging in nature, strictly visual. It can be caused by several different ways.

Sometimes "low quality" or more accurately poorly smelted SS is the problem. It could be something made with a great deal of recycled content so its like the wild west and no one knows whats in it.

It can also be contaminated with mild steel through dust or contact. We keep 100% of our SS tools separated from the mild steel tools. Also the stainless is fabricated in a sealed separated section of the building.

Most of the time it is the incorrect alloy that is used. A304 is not as "stain resistant" as is A316. A304 can perform well if it passivated correctly, and repeatedly if in a wet or marine environment.

SS fasteners are a whole different animal. The alloys used vary widely due to strength requirements, location of source, etc. Typically once removed, its a good idea to replace them if they are metal to metal contact. Stainless on stainless cold welds or galls very easily. Most people don't, but a lubricant is supposed to be used when you thread a stainless nut to a stainless bolt. If you clean previously corroded fasteners to re use, DO NOT use any sort of mild steel wire wheel or brush. Use a stainless steel one only.

Lastly if somone has stainless products that are showing signs of needing passivation,(rust looking spots or chalky look) you can use Citrisurf to passivate with out damaging the environment or other materials.

Look up Stellar Solutions or they have a lot of good information on there site if you care to read it.

I am not sure about other parts of the country but around here if you need some stainless steel fasteners in small quanity, we order them from McMaster Carr. Search
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Re: Rusted Stainless!

PostPosted by s219 » Wed Mar 16, 2016 1:27 pm

That is some great information Windy, especially to have all in one place.

I had to replace the bunks on my boat lift over the summer, and it became apparent the original installer must have used an impact gun and no lube on the stainless nuts and bolts. They were galled together badly, and I ended up breaking several 1/2" bolts because the nuts would not come loose even with me tugging on the end of a 24" breaker bar. I replaced the broken hardware and used Lanicote on the bolts. I had to adjust a bunk 6 months later, and the nuts came off easily.

It's amazing how stainless can cold weld to itself, especially if friction/speed enters into the equation...
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Re: Rusted Stainless!

PostPosted by Pinecrestjim » Wed Mar 16, 2016 2:14 pm

I'll second that the information is good to know. I guess I need to attend to some ss nuts and bolts I recently used for new LED trailer lights. I'll also read up on the link provided.
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Re: Rusted Stainless!

PostPosted by bwiley » Mon Mar 21, 2016 11:03 pm

Great Information. Thanks for the lengthy write ups
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Re: Rusted Stainless!

PostPosted by Uncleezra » Tue Mar 22, 2016 8:24 am

I must add, I work with S/S everyday, for over 20 years now. I do industrial metal fab. We work for light to heavy industry as well as the food industry. I have formed it, cut it, machined it and welded it. Most of what we use is type 304 which works in most applications but we use type 316 when chemicals are involved. The first thing we teach our new guys is that stainless is only rust free if we do all we can to keep it rust free. For example, not using grinding or polishing wheels that have been used on steel. Stainless is very rust proof but it will hold on to things that will rust. Tom is right on this. All metals have microscopic pores can trap rust. The first step to keeping S/S rust free is not to introduce rust. Trust me guys, it takes some pretty nasty chemicals to break down type 316 stainless steel. If you are having rust problems, its coming from someplace else.
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Re: Rusted Stainless!

PostPosted by The Sneaky Trout » Tue Jun 21, 2016 7:52 pm

A great remover for rust from your stainless is "Bar Keepers Friend" (

I let it sit for a while and it cleans up the rust rather easily from the stainless or areas where the stainless meets the hull. Non-acidic, non-corrosive and non-scratching.... just about everything you want in a stainless cleaner.

Edit -- Nevermind, as already mentioned by laidback...
laidback3 wrote:I thought this might be good to add to the thread. I use softscrub with bleach or dawn to clean the floor but stick to bar keepers friend for the stainless. 303 is great to wipe down the hull in between waxes.

Great list on the corrosive agents too, laidback. That's what made me re-read your post and see your mention of Bar Keepers Friend. You mentioned EZ-Off - the oven cleaner. To give you an idea of the corrosive nature of that stuff on metals, it will strip aluminum anodization. Take a piece of anodized alum, spray it down with EZ-off, let it sit in the sun for 15 to 20 mins, then hose off the anodization; you're left with bare aluminum.

As an aside - If anyone is looking for something to get the black mildew spots from the vinyl and under the well lids, use Tilex Mold & Mildew. No scrubbing needed.
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Re: Rusted Stainless!

PostPosted by Dune47 » Mon Jan 23, 2017 5:21 pm

Nice read!
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Re: Rusted Stainless!

PostPosted by meytchison » Tue Mar 28, 2017 1:12 pm

I was always told it is called stainless because it stains less than high carbon steel.
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