Rust Never Sleeps...Ed Sherman
Over 25 years ago I worked with a fellow named Mike Perreault who coined a phrase that I've never forgotten. Mike would say "Eddie just remember, "rust never sleeps". At that time we were in the process of trying to restore some ancient, rusted out Volkswagon beetles. Mike went on to become a real estate mogul in St. Augustine, FL. I'm still playing with rust. So much for career choices.
Today, being a raw, rainy, but sleepy December day here in Rhode Island where I live, I decided to visit the boatyard at the end of the street to see if I could catch any rust sleeping. I was looking for a special kind of rust, the kind that stainless steel makes. I took all of the photos in this piece within about 10 minutes. Mike is still right, rust not only never sleeps, its alive and well and super easy to find.
So, you may be wondering, hey what's up? I thought stainless steel was supposed to prevent this sort of thing. Well it is, but it has its limits which I'll explain here.
You see stainless steel is susceptible to a type of corrosion known as crevice corrosion. Stainless steel alloys typically used in marine construction need a vital ingredient to prevent them from rusting. The ingredient is oxygen. Oxygen, found either in air or water will cause the surface of stainless steel to oxidize and form what we call a passive layer that seals the metal and keeps it from rusting. In the absence of oxygen, or in an area where oxygen supply may be limited this all important layer will not form on the surface of the metal, and you guessed it, stainless will stain and rust readily. But it gets worse, crevice corrosion will really attack the metal and it will begin to pit and literally disappear. The problem with all of this is that it often happens in areas on your boat that you can't see without a little work. So, some examples of the rust I found in the first 5 minutes of my mission today are shown here:
No problem right? This swaged on wire rope attachment is only holding the headstay in place on a 36' cruising sailboat. On this boat the fitting is located near the waterline on the bow and constantly getting wet. The water is going right down the barrel of the swage fitting. The rust is coming out of the top of the barrel. The water gets trapped in the barrel, but is oxygen starved. I wonder what the stainless wire cable looks like? When this breaks, and it will, the mast could fall over......
On this one, you can see the rust just oozing out from under the mounting plate for this boardeing ladder bracket. No problem if the boarding ladder breaks off the back of the boat as someone tries to climb aboard right?
Or how about the one we see next, these bolts are holding a stanchion base in place.
No problem if the lifelines fall overboard as someone tries to work there way forward in heavy weather right?
How about the photo above? That shot is of a dinghy mount bracket on a swim platform for securing an inflatable to the platform while underway in a powerboat. No problem if the dinghy flies off the back of the boat at 30 knots right?
I like the one below. Yep, that's a tow ring on the back of a small powerboat. Nice heh?
My favorite is the next shot. Thats one of the bolts holding the swim platform onto the transom of a 36' trawler owned by an elderly couple. No problem if the platform falls off the back of the boat with one of them standing on it right?
So what's the solution here anyhow? No, its not one of the many rust stain removing products available in the market place. Sure they'll get rid of the rust stains, but you will not have fixed the problem. I hate to say it but crevice corrosion is potentially dangerous depending upon what the hardware involved is holding on to your boat. The photo below shows what's happening where you can't see it.
Yep, that's stainless steel, but it looks more like a Snickers bar that somebody took a bite out of. All of the corrosion took place inside the laminate that stud was pushed through. The stainless nuts were on the exterior, exposed to air, and vital oxygen, notice the relative lack of corrosion.
OK, so now the question is how do you avoid all of this and what can you do to save your boat? Well, in the case of the wire rope, you need a qualified rigger to assess the situation, and you may need some new rigging.
In the case of bolted on gear, the situation is not as grim. The fasteners need to be completely remove, the holes cleaned out with either a rat tail file (round) or run a similarly sized drill through the hole to clean out the perimeter of the hole. then you need to take away one of the key elements that's need for corrosion to occur, the electrolyte. 3M brand 4200 is my current favorite for sealing fasteners that may need to be removed later on. Use liberally. You want to see the sealer oozing out around the perimeter of the bolt or screw head to be sure the entire shank of the fastener is sealed from the water. No water, no hidden corrosion. Only after you go through this laborious drill can you rest easy. Only then will rust sleep.