Hi, I sail a recently acquired Nacra 20 (2006), essentially same boat as the Inter 20. The starboard shroud chainplate is loose in that it can be wiggled inboard and outboard about 1.5 mm or so. It does not move up or down or fore and aft. If you wiggle it and place your ear on the hull, you can hear the chainplate moving around in there.

I do not want to instantly jump to the conclusion that I need to install an inspection port and look from the inside. My understanding is that the chainplate forms a T-shape below the deck and that fiberglass roving passes through holes in the chainplate. This construction makes it seem unlikely that the entire plate would pull out of the boat. I also have never heard of such an instance on the Nacra 20.

My thought is that any movement can lead to further problems, and that I should dry out the area over winter and inject some West System inside to fill any void to arrest future movement and then just sail the boat. Any thoughts? Thanks!

I'm not familiar with the Nacra construction, but as a general rule, these anchor points should be rock solid. If you're able to wiggle the tang with your hand, then something has let go. Injecting epoxy isn't going to add any significant structural strength and may just end up masking a bigger problem. Inspection ports are pretty easy to install, I would just try to find out if there are any bulkheads in the area that need to be avoided and then pop in a 4" or 5" port to take a look.

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Its happened a few times before. A friend of mine fixed his by placing the area inside of the hull under vacuum and let that pull epoxy in from the outside.

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Greenville SC

Offering sails and other go fast parts for A-class catamarans
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If you do plan to install ports, I have the bulkheads location template. You want this before you cut!

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Philip
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I like the idea of installing an inspection port in the correct location (Thanks P.M.) to see what is going on and to dry out the area. I also like the idea of using light vacuum pressure to bring epoxy inside. Good to hear that this has happened before but is not associated with catastrophic failure, at least in the short term. Looking forward to doing the repair as suggested this winter. Thank you!