The forecast for next Monday is 11º C which means that it will be a good day to get some of the exterior glue and epoxy work done. In order to do that I have to prepare the work such that what remains on Monday is just the glue and epoxy work, no preparation.
This is the port companionway hatch runner and the grove is not in good shape, having been worn down over the years.
The part that needs to be fixed it the top part of the runner as it is this that prevents the hatch itself from coming off.
The runner needs attention along its entire length and the same is the case for the other side. To fix this the top “overhang” needs to be cut away, the wood and groove cleaned up and a new piece glued in place.
I started on the starboard side, just because, and just worked on a short section to prove the method. I tried using a plane to start with, but this was going to take too long. In the end I clamped a straight edge along the top of the runner where the cut needed to be made and scored the wood deeply with a utility knife. Then I used the multi-tool to cut down from the top following the scored line.
This proved to be quite successful, as you can see, and it did not take long to get the top “overhang” removed.
The groove itself was, in parts, completely blocked with multiple layers of varnish and I had to resort to using a chisel to remove them.
The result is fairly good and I cleaned up the rest using the block plane being careful not to remove any of the bottom of the groove.
The next task is to do the same thing to the port side.
This doesn’t take that long since I have already done the other side and know what to do this time.
I could have spent a lot of time getting both sides really smooth and vertical, but the replacement parts will be fixed using thickened epoxy so there is little point is spending too much time that will end up being wasted effort.
Next the replacements needs to be made and for this I used some left over Sapele from the Naiad rebuild that just happens to be the correct width. The pieces are too short and will need to be glued into longer pieces.
I cut them all to the correct height and took them into the workroom where it is warmer. Useful since my hands were cold again so I could warm them up as well as glueing the new pieces together.
As always with end grain glue ups, I coated the grain with an initial coat of glue and set the pieces aside for 15-20 minutes to let the glue seep into the grain.
After this time, more glue was applied to the pieces and glued together on a former, to keep them straight,
Each joint has a piece of baking paper put between the parts that must not be glued, then the whole thing is put over the Rayburn where it is hot and left for the glue to harden.
I had some time left over before it got too dark to work, so I attacked the port bulkhead that reinforces the canterplate case.
The work of about ten minutes with the multitool and the bulkhead is cut away. If I am very careful, this piece will be epoxied back into position once the centerplate case has been rebuilt. The starboard side will be rebuilt to match the port side as it was originally, rather than the cut down version.
Just before the light faded I put a second coat of varnish on the clock & barometer board and called it a day.
Every time I go into Shoal Waters’ cabin I wince at seeing the clock. It is a brass clock that has lost its clock bit, leaving just the outer case. A modern, plastic clock had been put into the case and the gap between the case and the clock filled with some type of foam strip.
Here it is. It’s quite good fix especially if you don’t want to spend the money on a new one, and they are expensive, but to me, it just looks wrong.
So, I’ve ordered a new brass clock.
Now with a forecast high of zero degrees Celsius today, it’s just 1 Celsius according to my weather station, I didn’t expect to get any work done today, but I decided that I could remove the old brass clock as it’s inside the cabin and therefore would not be so cold. The wind chill is pretty fierce outside today.
So I did.
And here is the result. the camera is wonky as I’m trying to hold a light to illuminate the area and hold the camera steady enough to take a non-blurry photo whilst also half kneeling in a small space.
But whilst I was attempting to take this photo I noticed that one of the bolts that holds the tabernacle to the boat is rusted. You can see it right next to the barometer to the right which has a lot of verdigris on the outside which is what rust on brass is called. This is not good. The bolts are stainless and rust on stainless steel is never a good sign. I’ll also have to remove the barometer and clean that up although the verdigris on the small screws holding it to the wood may not come loose. Still, I’ll cross that bridge when I come to it.
I had a look at the tabernacle from the outside since water was obviously getting in from outside and that meant that the bolt was no longer sealed.
Sure enough, the bolt is no longer tightened down properly, the tabernacle has lifted a little and the sealant has cracked. With rapidly numbing fingers I got out the requisite tools, removed the bolts and the tabernacle and took them into the workshop.
As you can see from above, the severely rusted bolt immediately sheared off the first time I tried to loosen the nut with a spanner. The bolt was rusty just about all the way through. I suspect therefore, that the bolt was originally bolted down tightly but the seal cracked over time and allowed the water in, which in turn caused the bolt to rust and that allowed the tabernacle and thus the bolt to lift making the issue worse. Ferrous Oxide, also known as rust has a volume that is ten times larger than the non-rusted steel and that is how the bolt was allowed to “stretch”.
The tabernacle itself is in good condition with a little surface discolouration. I’ll have to replace the bolts and I’ll make sure that they are marine grade 316, also known as A4, to try and prevent this from happening again. Normally you would only use 304 (or A2) stainless steel above the waterline, and the 316 grade below the waterline, but since these bolts are stainless but still rusting, I’ll pay the extra cost for the 316 grade.
I’ll also need to check the decking under the plywood and the beam underneath for rot and deal with that before I replace the bolts.
At this point I had to pack everything up and go back indoors. My fingers were totally numb and working with tools and numb fingers is never a good idea. I lasted just 30 minutes. The cold tools and the wind chill were too much. The tabernacle bolts had to be removed from the outside and the wind is from the North-West, straight into the Hay Barn.
Now I have to go through the slightly uncomfortable process of warming up very cold fingers.
Time for a cup of tea.
Once my fingers had warmed up I decided to try a few other short jobs. the first was to clear the old sealant from the deck where the tabernacle stands.
This is the state of the deck before I started work…
… and here is the after view. A lot of the deck under the tabernacle seems to be epoxy and I recall Charles writing in “Sailing Just for Fun” p37 footnote:
In May 1997 while Shoal Waters was on a trailer the mast hit an obstruction and ripped the tabernacle out of the foredeck. It was quickly and easily repaired.
I presume that the epoxy I found is part of that repair. I’ll have to clean up more of the remaining sealant and then I’ll probably skim that area with thickened epoxy to smooth it all off and to give it some more rigidity.
You’ll note the piece of Mahogany at the front of the cleaned up area, This is to tip the tabernacle aft a little to compensate for the slope of the foredeck in that area. If this were not done, when the mast was fully upright in the tabernacle, it would lean forward due to the slope.
Having done that and still being able to feel my fingers I moved into the cabin and set about removing the barameter.
The exterior of the barometer has been coated with varnish over the years but this has not prevented the retaining screws from degrading to the point that they could not be unscrewed. I resorted to slipping a flat-bladed screwdriver under the lip and levering the instrument off. It released very easily since the screw threads were now virtually non-existent and thus not gripping the wood any longer. It seemed that the barometer stayed in place due to the varnish than the retaining screws.
With the barometer removed I can now easily sand and revarnish the instrument board. It will also make it easier to replace the one bolt that almost touches the barometer.
I did take the opportunity to give the wood around the bolt holes a good poke with a sharp tool and found that the wood seems to be free from soft spots although there is quite a bit of salt residue that will need to be sanded away before the tabernacle is replaced. I also noted that the piece of wood upon which the clock and barometer were mounted fouls the two aftmost bolt holes and has been partially cut away to allow the bolts to protrude. However, the one on the starboard side hasn’t been removed enough causing the bolt to be canted slightly aft and this will have contributed to the leak,
As part of the work in refitting the bolts, I shall cut the backing board away completely around these holes such that the bolts can sit perpendicular to the deck.
The barometer seems to be in fairly good condition. It is partially covered in old varnish and part of the retaining lips has turned to copper, the zinc having been leached away by the water..
It is quite clear which is the upper side from the level of verdigris on the back and you can clearly see the old varnish and the three screws.
Here it is again but cleaned up a little. You can see the pinkish hue on the rim where the brass has turned to copper.
I don’t know if the barometer still operates, so having cleaned it up a bit more I took it inside to my office where I have the repeater for my weather station. I used the set screw in the back of the instrument to set it to the same value as the pressure reading on the station and I’ll keep an eye on it over the next few days to see if it tracks the same pressure.
If it does then I’ll replace it, if not then it will be retired and a new one purchased and installed in its place. Assuming that I can find one that small in solid brass, that is.
The reason why the centerplate case sides disintegrated is a question that has occupied my mind regularly since I first discovered the issue back at the beginning of August and I have come up with some wild ideas as well as a few prosaic ones. However, bearing in mind Occam’s Razor, I believe that the most likely reason is as follows:
Since the pivot bolt and thus the hole through which it runs, is underwater when the boat is floating, the bolt must be well tightened up in order to prevent the water from seeping through the hole and into the bilges. However, the sides of the case are only 8mm plywood with a stiffening piece on the outside of the case.
You can see the stiffening piece on the side of the new case above.
If the pivot bolt is tightened too much the sides of the case will bend inwards excessively and a spacer is inserted between the sides to prevent this.
The is the spacer. the plate pivots on the centre section and the two wide ends press against the sides of the case. I presume that the spacer was a good fit but not a tight fit and tightening up the pivot bolt did bend the sides of the case in just a little and this made the joint between the case and the spaces very tight, tight enough to stop water from getting into the hole.
So far, so good. Now Charles Stock reinforced the sides of the centerplate case when he was building Shoal Waters and my conjecture is that this added so much stiffness to the sides of the case that when the pivot bolt was tightened enough to stop the water getting into the boat, during the occasional pivot bolt inspection, it prevented the sides of the case from bending inwards slightly and forming a good seal with the spacer. This in turn allowed water to seep into the end grain exposed by the hole in the plywood and over the decades water had been slowly seeping into the original layer of plywood on both sides, eventually causing the disintegration we see today.
This explanation is contingent upon two things only. Firstly that the end grain exposed by hole through the original plywood was not sealed and secondly, the additional stiffness of the case sides prevented a good seal being made between the spacer and the case sides.
All the other explanations I have come up with require more than two contingencies.
Alas, we shall never know if I am right but the mechanism is valid and a concern for the new centerplate sides. To prevent this from happening again is simple, just seal the end grain in the hole.
Simple in concept, but not so simple to achieve reliably, especially when the hole is only 10 mm in diameter and is nearly 40 mm deep. To completely seal the end grain I decided to use a technique that I used for all such holes in Naiad.
I drilled out the hole to 13 mm and placed tape across both ends. The top end was cut to open the hole as seen above.
Epoxy thickened with low-density filler was poured into the hole to completely fill it and the epoxy allowed to cure. The epoxy was about the consistency of thick double-cream but liquid enough to easily soak into the sides of the hole, from top to bottom. Once this has completely cured I will sand the epoxy flat with the wood and drill a 10 mm hole through the epoxy which will leave 1.5 mm of epoxy between the hole and the plywood and the hole will be completely sealed.
Overkill?
Certainly, perhaps even overkill to the overkill, but quick and easy to do, so why not?
Time for a cup of tea.
The result after the epoxy has cured and the hole drilled.
