Chain Plate Replacement
During the Main Mast Rebuild 2001, I had noticed there was some rusty water leaking out of the bolts that were used to hold the chain plates to the hull. I had always been pretty conscientious about sealing the chain plates where they came through the cap rail, but I also knew that in reality there is no way to stop them from leaking. The really bad news is that the chain plates were on the inside of the hull and then fiberglassed over, so there was no way to do an inspection without major work. I then decided to chop out the old chain plates and replace them with new chain plates, through bolted and attached on the outside of the hull. A major project was looming!!
One item that I had always wanted to do since I purchased the boat was remove the tri-atic stay that went from the top of the main mast to the top of the mizzen mast. I felt that if the boat ever did a 180 or 360, if the masts were not tied to each other, there was a chance that the boat would right itself with at least one mast standing. This would necessiate a forward leading shroud from the top of the mizzen mast with attachment to a new chain plate on both sides of the boat.
Since I was going to get into this project in a big way, I thought that I would also add an intermediate shroud on either side of the main mast for the stay sail stay. There was no support for this stay, and I was always concerned that in a heavy sea with just the staysail up, the main mast would start working and break at the staysail stay attachment point. This would also require additional chainplates.
Once the decision was made to get into the project, I decided that all of the new chainplates would be on the outside of the hull for easy inspection and repair. The old chainplates were of 3/16" X 1 1/4" X approximately 10" long. The old chainplates each had two 3/8" bolts holding them to the hull, plus the fibreglass to the hull. The new chainplates were made from 316 Stainless Steel bar stock. The size is 5/16" X 1 3/4" X at least 24" They would be through bolted to the hull with at least 4 1/2" bolts, each with a backing plate.
In each case to remove the existing chainplates, cabinets, bulkheads or shelving had to be removed. Once the furniture was removed I was then able to cut out the trim liner that covered the hull. This exposed a polyester filler between the hull and liner that had to be cut out using the air chisel. After the filler was cut out I had access to the fibreglass that was covering the old chainplate. This fibreglass had to be cut out to gain access to the old chainplate for removal. For this I used an air powered chisel. When I cut into each fibreglass covering of a chainplate, rusty water ran out! Some more than others, but it made me realize that I was doing the right thing. After removing the rusty chainplate and cleaning up the area, I filled in the area with fibreglass to make it as thick or more as the hull. I then used a polyester fibreglass reinforced filler to create a flat surface on the inside of the hull for the backing plate.
While all of this work was going on inside the boat I was also working on the actual new chainplates. I purchased 12' sections of 316 Stainless Steel flatbar and cut them to the proper length. These pieces were drilled, and trimmed up as necessary. They were then sanded with 120 grit sandpaper, 220 grit sandpaper, and then 320 grit sandpaper. The chainplates were then sent off to be electropolished.
These first pictures will show the work done in the mid-cabin. These chainplates were for the starboard side of the main mast. I had decided to put the chainplate for the upper shroud over the port rather than take the port out and fill in the hole in the hull. Sounds a bit strange, but it worked out well. Before the trim could be removed I had to remove DC and AC wiring, shelving, supports and cabinets. It will show the trim removed, also show the filler that the builder used to fill the gap between the trim liner and the hull, the glass cut out to expose the old chainplates, the area glassed in and the the filler put in. Finally it will show the finished product from the inside of the boat.
This second group of pictures will show the efforts put into replacing the chainplates on the port side that were used for the main mast backstay and the mizzen mast upper shroud. It will show the same basic cycle that went into the midcabin. Shelving, supports, cabinets and wiring had to be removed before the fibreglass could be removed that covered the chainplates.
This next group of pictures will show the starboard side aft chainplate portion of the project. This chainplate was in the head. I did not have to remove quite as much installed furniture for this, but because the bulkhead between the head and garage was completely rotten and had to be replaced, the finished pictures of the starboard chainplate will be in the Head Bulkhead Replacement Section. A disturbing thing happened on this chainplate replacement. When I started to chip away the fibreglass covering of the chainplate, the whole piece of fibreglass fell off! I did get a bunch of water coming out, but the fact is the fibreglass was not very well done.
These next few pictures are from the storeroom. The storeroom used to be the second head on the boat. I had already stripped down this area to the bare hull, so getting to the chainplates was not very difficult. I had to remove some wires and cut out a bulkhead between the storeroom and the hanging locker, as the forward chainplate was right at the bulkhead. This is where I actually started the chainplate project.
This next group of pictures shows the chainplates under construction and in the truck before they head off to the electropolisher.
This last group of pictures shows some of the finished products on the boat. There are pictures of the port side new aft chainplate for the main mast backstay/mizzen mast upper shroud. Some pictures of the chainplates for the main mast upper shroud, lower shrouds and the new intermediate shroud.