Unfortunately, this will need attention, as most likely there is some delamination of the deck at the chainplate.

Chainplates are very prone to leaking where they go through the deck. Even after careful rebedding they can leak again relatevely soon due to the movement of the chainplate when sailing. Even if the water isn't making it into the interior of the boat, it can be making it into the balsa core. Unfortunately, this tends to rot the balsa deck core around the chainplates--particularly in fresh water environments. It is even worse in climates that freeze, as the fresh water freeze/thaw cycle breaks down balsa and invites rot.

A crack extending from the chainplate is likely caused because the balsa core has degraded in the area from years of leaking. Take a something hard (like the hard plastic handle of a screwdriver) and tap all around the chainplate on deck. If you get a hard knock, the core is good. If you get a soft mushy knock then there is delamination and/or rotten core. You may be able to determine the rough extent of damage this way.

The correct fix is to cut out the rotten core and replace, then reglass the deck. Generally this is done from above because the main bulkhead intersects the deck by the chainplates making repairs from below very difficult. This is not a trivial repair to do well and best left to someone with experience. That said, it is not catastrophic either and can be effectively repaired without major surgery.

If you don't yet have delamination in this area, it is worth preventing it by removing the chainplate, augering out the balsa around the slot, and filling it with epoxy to make a waterproof seal against further intrusion.

I just resealed my chainplates a couple weeks ago, as they were leaking despite careful sealing about 5-7 years ago. Expect that sealing the chainplates is something that needs to be done somewhat regularly.

Feel free to email me directly with further questions.

--brendan

:: Today I noticed a 4" crack in the deck extending from
:: the chainplate on the starboard side to a nearby
:: fitting. Is this something to keep an eye on or a more
:: serious matter? Does anyone have a recommendation for
:: someone to take at look at the problem?