2016.04.03 - Plodding On
Preparing the bottom of the hull by sanding off the many coats of antifouling paint and sanding the copper layer to a good finish has been a chore. I contacted the prior owner and asked him about the copper and he told me that it was Copperbot that he applied when he first bough Naiad after sanding the bottom back to the wood. However, after moving the boat to a swinging mooring in St Just Creek later on he found that the copper did not seem to work and, on the advice of the locals, over-coated the copper with normal antifouling.
There are three problems with sanding antifouling paint and Copperbot. The first is that the antifouling is a poison so you have to wear a good breathing mask. The second is that the Copperbot, being more than 80% pure copper is very tough, you are in effect sanding nearly pure metal and this takes a lot of sandpaper and thirdly, the copper dust produced is so fine that it penetrates the breaking mask filters with ease, meaning that you are breathing copper dust and also eventually shorts out the motors of the sanding equipment and my dust extractor
Still, after buying a new orbital sander and a dust extractor, the job is done.
Yesterday I turned Naiad the right way up and put her back on her trailer. I also put the sailing pram dinghy outside on the trade that Naiad has been using whist inverted. The dinghy is just too much in the way. This lead to a cleaning up exercise and a trip to the local recycling centre this morning as well as levelling the hull ready for the next phase.
I also started to sand in the inside of the repair but after gouging a chunk out of my hand on a protruding bolt I stopped that and decided that the 12 protruding bolts, 6 either side, had to go. Right now!
They will have to be removed shortly anyway as I intend to put in ribs just where they are placed. I have left these bolts until now as they were put into a backing pad of mahogany and then the backing pad was fixed to the hull with the heads of the bolts between the pad and the hull. There’s no way to remove the bolts without first removing the pad. I just knew that this was going to be hard.
The previous owner was a specialist aircraft mechanic. Still not clear? Well, consider this. Losing bolts on any aircraft especially in flight is not a desirable event. So the rules and regulations concerning the way in which parts of the aircraft are bolted together are strict. You never, ever rely on just one thing to keep a bolt securely fastened. Bolts will have spring washers or be self-locking and will also be further secured using an approved thread locking liquid and in high vibration areas may well have a split pin or other retaining system, just in case.
Well, Naiad has been fitted out like this.
Take this backing pad. The fitting that was attached to the 6 protruding bolts was the attachment point for the mast shrouds and stopped the mast from falling down sideways. When sailing the tension on these fittings could be considerable, hundreds of Newtons of force. So, the fitting was stainless steel as were the bolt and I fully expected the backing pad to be glued and screwed to the hull.
Theoretically , it should be a simple job. Locate the screw heads on the outside of the hull, remove the filler that covers them, clean up the slot in the screw head and unscrew. Simple, yes?
To start with there were 11 areas of filler and 3 of these turned out to be covering screws that had sheared off. So 8 stainless steel screw heads in good condition. Would they unscrew? No. Well one did partially and that’s when I found that they were bolts and not screws. It would unscrew a short way and then just turn and not come out any further. In the end I had to destroy the backing pad using a chisel, use a spanner to remove the nuts which had been secured using thread lock, then remove the rest of the backing pad as the bolt had been glued into the wood. Finally hammering the bolt from the inside broke the glue and I could remove the bolt completely.
I’ve done one and now I’m having a coffee and a sit down before removing the second. This time I know what to do in order to get it removed.
The protruding bolts and the backing pad.
The backing pad tired from the other side of the boat.
There’s filler under that paint somewhere!
Eleven new holes to be filled, three not going anywhere. You can see where the hull has been damaged on the top two bolt holes where the glue holding the bolt in place has seeped in to the wood pulling the hull away when the bolt was hammered out.
The pad removed and the hull cleaned up.
The remains of the backing pad.
The heads of the bolts exposed for the second backing pad.
The remains of the second backing pad showing the bolts on the inside.
The bolts unscrewed a short distance so that the slots can be properly cleaned up.