Lena
Invader 22
My main site home allsorts *** *** Baring her bottom !
1   
2     
  3     
4      
I'll have to get a close up of one of these - with something to scale
stuck next to it, just to show the thickness of the gel coat.
A sudden wave of warm weather - so I decided to take advantage and strip the rest of the anti foul.
Fortunately it had been applied to new untouched gelcoat - so despite being about 20 layers worth - it scraped off pretty easily.
1
The Starboard fore scraped off - left the bottom between the keels to last ! The port side had already been partly done when I aquired the boat - so was pleased to find nearly the while of this side blister free.
2
This is really the extent of any blistering on the entire starboard side. Also it's nice to be able to go back to untouched original gelcoat. Apart from the very base of the keels, this hull has never been touched from new. The blisters here are no more than 10mm across and mostly confined to the central lower section of the mid-keel.
3
Port side, the area that was already stripped of antifoul when I bought the boat. I have ground them out - thought about it and decided it was better to take them all out. I used my mini-grinder with a round corundum wheel about 12mm diam - works great. Just pop it end on against the bubble - then wiggle it around. End on - it sort of meets a resistance when it gets to hard layup - so only grinds sideways. Mind you - the gelcoat on this boat is over 1mm thick - and there seems to be very solid layup immediately below. The hull here has been completely sripped of antifoul - and I've started matting off the surface with 180 wet/dry - which is actually quite a process as there's quite a layer of release stuff on the gel - grease, in other words.
4
Close up of the main blisters I opened out on the port side. These pockets are on average about 15 - 20mm across - largest of the blisters 10mm. Also - everything seems very dry below.
After all, if the layup was wet, I can't imagine the mini tool producing the fine white dust it did - and no clogging. I was going to get a super macro of the ground out blister - but it was just about to belt down with rain.
See - thoughts on osmosis, for more details, inc my eventual choice for epoxy coating.