Hull to deck joint leaks: how surveyors trace them and write them up

The hull to deck joint is where the deck sits on the hull's flange, sealed and fastened with bolts, screws or rivets, then usually hidden under a toe rail or rub rail. Safe Skipper notes these joints are designed not to come apart, permanently bonded, often covered up and sometimes glassed in. When one leaks, water runs along the inside of the hull into lockers, behind linings and into bunks.

How a surveyor checks it

Look inside first. Follow the joint through every locker and behind any lining you can open: water stains, salt, rust streaks from bolts, and soft or rotten wood all mark leaks. Check the nuts and the sealant.

Then outside. Look along the toe rail and rub rail, and at every fitting through the deck near the edge: stanchions, cleats, genoa tracks, chocks. Safe Skipper points to deck fittings and cleats that have had excessive strain. A hose test with someone inside shows where water actually comes in.

Finally, load the joint where you can. A joint that opens or moves when a shroud, a cleat or a fender line is loaded has failed.

What decides the grade

Whether the joint is still holding the deck on. Opening, moving or pulled fastenings is an A. An active leak with corroded fastenings or rot is a B. Old stains with no current leak are a C.

What repair involves

Safe Skipper's repair: polyurethane sealant in the joint, through-bolts where possible, and sealant kept off the nuts so it can be undone later.

Photos to take

Stains and corroded fastenings inside, the toe rail and fittings above, and any gap in the joint. With Axsail, say what you found on the hose test as you take the photos and they go on the hull finding.

Writing it up

Give the location along the joint, the inside evidence, the condition of fastenings, what the hose test showed and whether the joint moves. Name the likely entry point, or say it wasn't found.