Changing through-hulls between tides?

[ColinR]

I definitely don't recommend this, but I did it once afloat. The galley seacock had failed open so with trepidation I unscrewed it, held my thumb over the skin fitting, got a new one in place despite the fountain of water that shot out, screwed it down and its been there ever since. Stupid I know but I got away with it.

 

[srm]

No problem, have done it on a couple of boats. The last time was fitting a hull cooling plate for the fridge so had to drill the hole as well. Just have everything ready including reinforcing pads if changing the skin fitting. As far as possible ensure they will all fit. Also, a back up plan to plug any holes while you wait for the next low water to finish, though I had plenty of time on both jobs.

If possible choose a drying out spot so the keel touches bottom just after HW, but will float again at the next HW, to give the longest working time.

In your case I would suggest having a new skin fitting and any backing pads ready, as you may damage the existing fitting while removing the valve.

Angle grinder and discs make rapid removal of old fittings easier though they can be removed with hacksaw and cold chisel.