Screwing around
I imagine that the next few weeks will be taken up with the same mundane work that has been going on during the last week or so. That means that this blog is going to be pretty dull for a while I fear. There are over 2000 screws holding the planks to the frames and a lot of them are broken or corroded. Let’s start with what you see once you get the bungs off.
The first task is to clear the slot as well as possible.
In a perfect world you can get a screwdriver or bit brace into the slot and get the screw out the usual way. More often than not, the screw breaks somewhere along its length.
When that happens, you’ll often get a screw that just spins in its hole. That means you have to pry it out somehow as you turn it. One way to do it is to get a thin blade under the screw head and use it to gently pry up as you twist the screw.
The problem is that this method damages the fragile mahogany around the screw hole.
You really want to do as little of that as possible. One trick that I found works is to use curved dental tools to get under the screw head. This causes far less damage to the hole. Unfortunately, all these methods are slow slow slow.
Once you get the broken screw out, there’s still the problem of the remaining bit of screw left in the hole. The only way to get it out is using a an unscrew-em. If the screw is corroded enough, each time you get a little bit out, it breaks again. The problem is that the unscrew-em is hollow, and it gets clogged with the broken screw bit.
So, you take it off your drill, poke out the bit of screw, re-mount it on the drill, and go at it again.
Other times, the slot will break off when you begin to unscrew it. We’ve tried using EZ outs (the reverse-threaded bolt and screw removers) but I think the soft and corroded bronze doesn’t work well with this system. The method we’ve found that works best is to grind a hollow into the screw head using an air powered die grinder.
You could also use a Dremel tool to get the same results. What we’re shooting for is a good sized depression in the head.
This bowl shape guides the unscrew-em into the center of the screw.
And with a little luck, you can get the screw out rather quickly.
Still, the process is slow. It can take 15 minutes to get a single screw out if it’s at all rotten.
Sometimes you get a series of screws that come right out. Other times, you get a whole patch of broken ones. Below is the field of screws that hold 2 planks on where they butt up to each other. Behind all those screws is a butt block (and for the eagle eyed among you who noticed the asymmetry in the screw patterns, yes, there’s one more bung that needs to be removed). All but 2 of these screwheads broke and needed to be extracted with the die grinder and unscrew-em.
It takes a lot of patience to do this work sometimes. We had originally estimated that it would only take 2 weeks to refasten the whole hull. We’re at 2 weeks now and are probably 1/3 the way through.
Still, it’s a good lesson in estimating. I think we’d have lost our shirts if we were charging based on our original time estimates.
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