Sailfeed
March 23rd

Being nearly finished with a bunch of big boat projects I’m at a bit of a lull with the blog at the moment.  I have plenty keeping me busy but little to write about until I’ve actually completed some of them. In the meantime I dug up some photos of failed hardware and the scariest DIY ‘repairs’ I found on my boat. I’m all for fudging things a little when I think I can get away with it, but this stuff is crazy!

Exhibit A: The Through-hulls
After buying my boat in Florida my original plan to sail her back to New Orleans was stymied by a couple of very sketchy through-hull fittings (The backstory is in this post). This is what they looked like:

Aside from the obvious corrosion, neither of these fittings have proper marine seacocks. Instead, gate valves have been used, a poor solution because of their greater fragility. Our suspicions were that these fittings were made of brass rather than bronze and so corroded that they were likely to break off if I ever had  to try and close them. Once the boat was hauled I tested and removed them. We were right to be worried. One sheared right off and while the other seemed operational both were so corroded that I needed an angle grinder to get them out. This was a bit of a nuisance but turned out to be an interesting lesson in metallurgy.

Here are the through-hulls and ‘seacocks’ after removal:

While it looks more corroded the one on the left was actually functional while the one on the right was completely compromised. This has to do with the composition of the metals. Here’s another view:

On the left is the valve which functioned, on
the right the one which simply snapped off. 

If you look closely at where I cut through the metal you’ll notice the one on the left is a reddish yellow while the right one is more golden. This reddish yellow is actually bronze, the proper material for through-hulls and seacocks while the golden yellow on the right is brass, a material highly unsuited for the marine environment.

Yellow brass, which is a fraction of the price of bronze and all too often used by DIYers and even builders  on a budget is composed of about 40% zinc and 60% copper. When exposed to saltwater the zinc corrodes while the copper remains intact, much like the zincs on your prop shaft which protect the rest of the boat by corroding first. This process, called dezincification, makes the metal extremely brittle and gives it a pinkish color, kind of like this:

This is where the through-hull snapped off in my
 hand when I tried to close the gate-valve ‘seacock’. 
Here’s another view:
Despite the color difference you’re looking at the same piece of cheap yellow brass on top and bottom. The bit on top has turned pink because of dezincification.
In comparison, the bronze through-hull and gate valve (pictured on the left in the first two photos) had suffered only surface corrosion. It would probably have been ok despite the improper use of a gate valve instead of a marine seacock (tapered plug or ball valve). But there was no way to know what metal it was made of without chopping it up and below-the-waterline hardware is not something I want to gamble on!
Exhibit B: Holes in the hull
Speaking of below-the-waterline gambles, here’s the scariest ‘repair’ I found on the boat:
When I noticed this, well, ‘thing,’ on the hull a few feet below the waterline I was quite confused as I couldn’t think of anything on the inside it might correlate to. Not sure what it was I did a little digging around with a screwdriver and with a squelch the thing popped right out!

 Or rather, it popped right in, dropping into the bilges. Digging around I retrieved the nut/bolt/washer combo shown on the left in this photo:

That’s right, there was a 1″ hole in the bottom of my boat, well below the waterline, plugged only by a washer held in place with caulk and whatever gunk was clogging up the bilges! It’s inexplicable and totally insane, but that’s what I found. 
So how could this have happened? My guess is that some foolish owner (or shockingly bad boatyard) pulled out a through-hull and then decided to plug the hole with just a bolt. As for how it came to be held in place by only the caulking I suspect that there was originally a washer on each side but the outside washer must have corroded away completely leaving only a bolt head small enough to fall through the hole. It is absolutely remarkable that this didn’t sink the boat. 
And there’s more! Here’s another photo of that area of the hull:
If you look at the bottom left of this shot you’ll see another bolt head. This is the relatively clean-looking bolt which is on the right in the previous photo. Once again it is being used to plug a hole in the hull, this time a smaller hole which functions as a bilge drain. Once again, this is a very sketchy situation! 
The theory behind it is not bad and I’m going to keep the drain hole and actually plug it in the same way – with a washer through-bolted in place. The problem is that whoever installed it used stainless steel, an absolute no-no below the waterline. Stainless needs oxygen to remain corrosion free and immersed in saltwater it has a very limited lifespan. It would only have been a matter of time before this bolt went the way of the first one, though it is likely that by the time it corroded out the first one would have already sunk the boat! I will be replacing it with a bronze bolt and washer, bronze being the only reasonable choice for below-the-waterline fittings. 
Now that I know the crazy chances some people are willing to take if I’m ever again thinking about buying a boat I’ll be sure to dive on it and check every inch of the hull!

This article was syndicated from Safe At Harbour But Meant For The Sea: DIY Sailing with Paul Calder

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