A while back I installed a Lewmar chain stopper on the foredeck to make anchoring a bit easier. It was a simple job to fashion a mounting block out of teak, make a backing plate out of apitong and bolt it all together. The job was done in a day. Then I went out and anchored and discovered that if I left it as is, the stopper would soon knock all the galvanizing off the chain. This is a standard flapper type chain stopper, rated at 5,000 lb SWL and sized for 5/16 chain. I had used this unit on my last boat, which had 1/4" chain and a vertical capstan windlass, and it worked well. The problem is that there is barely enough clearance in the stopper for the chain to pass through, and only if it is perfectly aligned and set at an angle that matches the angle of the chain as it passes from the windlass to the roller. On top of that, the deck in that area is only about half an inch thick. It is made of a fairly heavy fiberglass laminate and a bit of wood core. This isnt really enough structure to simply throughbolt the stopper to, so I added a carbon fiber top plate and a larger wood backing plate to bring it up to snuff. The photos below outline the process.
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| Mold. |
First I measured the amount of crown in the deck forward of the anchor locker. Its nearly flat but I wanted the edges of the top plate to fit tightly to the deck so I created a bit of extra curvature in the mold, which is made of a piece of old 1/4" Starboard.
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| Paper pattern with pre-cut carbon fiber |
I took a template off the deck and drew the shape in AutoCad. I wanted the top plate to be fairly large so I could attach it to the deck with several widely spaced fasteners to spread the loads out as much as possible. The rectangular shape is the outline of the teak mounting block.
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| Laminating the carbon fiber |
I used four layers of Vectorply C-LT2200 carbon fiber cloth for the laminate. This fabric is made of carbon fiber bundles aligned along the 0 degree and 90 degree axes of the roll and stitched together. This architecture is stronger than traditional woven fabric. The four layers amounted to about 88 ounces/sq yd of material for a total thickness of about 3/16" when it was finished.
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| Second layer is rotated 45 degrees |
I oriented the first and fourth layers so the fibers run at 0 and 90 degrees to the centerline of the boat and rotated the second and third 45 degrees to provide strength in all directions. I used WEST systems resin which works really well for hand
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