A quick look at the through-hulls shows us that they need to be replaced.
Most of the valves are oxidized and blocked. The locknuts have been embedded in a hard plastic to seal the leaks that have appeared over time. All are very oxidized and this does not help us to get them out either. It is impossible to unscrew the lock nut, the radical method is necessary : grind the through-hulls from the outside and blow them up.
The exercise is quite tricky and rather scary. It consists in cutting the outer lip of the through-hull with a grinder in order to make it jump inside the boat by tapping it. Small detail, this same lip is in contact with the hull. The slightest false move and the hull is quickly cut. This is of course what happened on the first try... The 4 following ones were more successful.
Once the through-hulls have been removed, it remains to make a clean spot for the new ones. We remove the Sika remaining in the hole with a flexible blade. A shot of degreaser is passed to remove the last residues. The part of the hull having received a blow of disconnector and presenting a notch of 2 cm length on 5 mm of depth is ground then repaired with an epoxy putty.
The installation of the new through-hulls is adventurous insofar as Émilien is alone to carry it out. The main trap is to think about the correct positioning of the male part of the through-hull from an angular point of view to ensure the necessary clearance for the operation of the valve ¾ once it is in place inside. Therefore, all the parts must be assembled: through-hull, locknut and valve simulate the clearance induced by the Sika gasket. The valve is positioned correctly by turning the assembly. Then mark the position of the grommet on the outside with a felt-tip pen. We can then remove everything and follow the classic method: Sika, grommet + locknut tightened by hand. 24 hours later, the locknut is tightened by about a quarter turn with a wrench to compress the Sika gasket that has dried in the meantime and to ensure the seal.
Tools : Grinder, Sika, epoxy putty, flexible blade