Last time, I was trying to decide whether or not to completely refasten the hull planks. Part of that decision depends on how hard it will be to get these things out, vs. drilling new fasteners next to the old ones. As its clear that the entire hull, and the (I'm not sure what its called) deck planks around the edge of the deck, are all steel, this is going to entail a lot of work. The steel screws below the waterline are in pretty bad shape, as seen in the photo below. In come cases, there's barely anything left.
With the amount of work ahead of me, I've decided to try out as many fastener removal methods as possible. Here's what I've come up with.
Brace and Bit
I saw in an article (I think it was in WoodenBoat) about an old surveyor who specialized in wooden boats. In it he talked about always carrying a bit and brace with him to remove fasteners, and how you can't really survey a wooden boat without removing a variety of samples from different areas of the boat. So I figured if its good enough for him, it has to be work a try. I already had a brace, but finding the bits was another story. I found some on ebay, but would really like to find a supplier so that I could get the correct sizes.
For screws that are in decent shape, the brace is really a perfect tool, you can put good pressure on the bit, and get plenty of torque. The Brace has become my first step in the removal process. If the the screw doesn't let go immediately, or if the bit slips more than once, I move on to step 2.
Impact Driver
The impact driver is typically used by machinist and engine folks to back out frozen screws and bolts. My father had used them several times while pimping out my cousin's old Jeep and suggested I try it. the first time I used it though it was a little scary. I tried to remove one of the deck screws on the port side near the transom; this area has had a lot moisture penetration because of the end grain of the deck. This was probably a bad spot to use for a trial of this tool, because when I started hitting it with the hammer, it just pushed into the whole. This freaked me out a bit, as I thought that the tool was pushing the screw through the boat just due to being overpowering. I later found that the reason it did this was that the screw in question had basically rusted away to nothing. The trick with this tool is not to hit it too hard, and to be sure you have a good, sharp bit. If I can't get a screw out, or at least loose, with this tool, I move on to the heavier artillery.
Screw extractor
If neither the brace, nor the Impact driver do the trick, I move on to the extractor. This one involved drilling a hole in the screw and using a reverse twisted bit to get grip and back it out. This one took a lot of trial and error to get to the optimum method. I started out trying to use it with the bit brace, which worked a few times, the risk was that I broke a few extractors due the torque the brace can deliver. In the end, I've decided on the following process:
drill a hole in the screw
Set the bit into the hole using a few light taps from a hammer
Attach a tap handle to attempt to back out the screw.
This has worked for the most part, but I have had a few screws that just will not budge no matter how much torque I apply. I'm amazed that the screw can be in there that tight, but I've heard from a few people stories about some chemical reaction with the rusting process that actually allow the screw to adhere better to the wood; but this is shocking to me as in some cases most of the wood around the screw is basically soft. If the extractor doesn't work, its on to the nuclear option.
Hole saw extractor
If all else fails, or if an extractor bit breaks off in the screw, its time for the option of last resort. The hole saw extractor. The idea is that you saw out the screw and surrounding wood using a hole saw that is the same outside diameter of the bung. After sawing you pull the screw and wood out and then fill the hole with a dowel of the same size, then redrill, countersink, screw and bung. I've been a bit suspicious of this option because the dowel will be the opposite grain direction of the planks, and the frames, so I worry about it swelling and splitting.
