Seacocks ... sealing with?

[vyv_cox]

I've always left them.

But your comments about 'bonding' have opened another very large can labelled 'WORMS'.
At the very least, it's an unnecessary complication.

Indeed so. Absolutely no need to bond bronze seacocks and doing so could introduce many other problems.

 

[ghostlymoron]

I'd use PU40 to seal between skin fitting and hull. I don't go for the 'nip up after curing' technique as you risk unseating the joint which could cause a leak.

As a corollary to this, I replaced a sea cock a couple of years ago. The skin fitting was fine so didn't replace it. I was careful not to disturb the skin fitting during replacement but when I relaunched, there was an annoying little weep around it necessitating hauling out and doing the job again (plus costs). I learnt two lessons from this; 1. Don't cut corners - I should have refitted the skin fitting in the first place. 2. Don't disturb a joint once made.

 

[rszemeti]

I suspect the skin fitting I had were fine, however after I had disturbed them to remove and replace the seacocks, the only way to easily remove them was to cut them out ... so replacement was inevitable. The cost of an extra 2 skin fittings is but nought comapred to the costs of a haul out and re-launch.