I had some work to do on the CNC Laser after work and while that was running I decided to look at some of the pieces I removed from the top of the case yesterday.
This is one of them and exhibits one of the things that Charles Stock did consistently wrong when building and maintaining Shoal Waters. He used brass screws. You can see the result in this piece of wood quite clearly, the discoloured circles of wood around the places that the screws were put originally.
This is the view from the other side and you will see that either the screw is missing completely or the zinc has leached out of the brass leaving just copper. These copper fastenings need to be removed and the wood repaired before it is put back in place. Still, enough of that, it was time to move back to the centerplate case. Armed with a multitool with a sharp, fresh blade I set to.
This is the result, a hole in the starboard side of the case. I had to say that it was either a very sharp blade on the tool or it was distressingly easy to cut through the side of the case.
This is the section that I cut out viewed from the inside face.
Looking down the slot through the opening I could easily see the metal spacer and it was easy to fish out with just my fingers.
It is the spacer through which the pivot bolt passes and its purpose is to prevent the bolt from crushing the case inwards when it is tightened. Too loose and the water will get in as the seal is not good enough, but tight enough to stop the water ingress would also deform the sides of the case. But with this spacer in the way, that deformation is prevented.
Back in the workshop I took a closer look at the section of the case that I had just cut out. It is in very poor shape as you can see. This large flake of wood came off just using my fingers.
And this was cause by scraping the wood with a screwdriver. It’s totally rotten. The inner face of the case seems to have been coated with something, presumably to stop the steel plate from damaging the wood, but under that it is soft and fragile.
Looking at the end of the cut piece you can see the plywood that Tony glued to the outside of the case to reinforce it. This split away from the original casing when I prised the section out. Then there is a fairly intact middle layer of plywood and then the darker part that is the rotted plywood. It looks as though the sides of the case were made from two piece of plywood glued together with something like Aerolite glue and the inner face of the case covered with something, perhaps Aerolite glue again, as protection. Over the years the rot has gotten into the inner layer of plywood but has not been able to cross the glue barrier into the original outer layer of plywood except where close to the pivot bolt hole.
As a final task for today I took a screwdriver to the other side of the case and as you can see form the above photo, it too is severely compromised. The conclusion I draw from examination of the casing is that the rot has spread at least as far as the solid ends and will therefore need to be completely removed and replaced with a new case.
Now that I have the side of the case opened up I can see that this isn’t going to be such a difficult job as I had first thought. I will have to cut away the two side reinforcing bulkheads, which is mildly annoying but has to be done, before cutting the case as close to the keel as possible. The idea being that if I’m careful with the removal I should be able to use the removed case as a pattern for the new one.
We shall see.
I’m fairly confident, however, that if Tony Smith had not reinforced the case when he did then Shoal Waters would have sunk, either on her mooring or, more likely, when being sailed and the leverage of the water on the centerplate on the case cracked the case apart. Scary to think about.
Still, a new case made from high quality marine plywood from Robbins Timber will put her back into sailing condition for many years to come.
I just have to get on and do it.
Time for a cup of tea.