I had thought it only happens to guys with coppercoated hulls: Found pitting corrosion on my own boat's keelbands and fastening screws. Now that is serious, and I do not know how I can fix myself such a major defect.
I found it after my centreboard uphaul rope had torn, and the board had swung violently down and forward until hitting the forward wall of the centreboard case opening between the keelbands. BANG!! There must have been a mighty shock on the pivoting pin also, and on the keelbands holding it in place.
So I inspected the keelbands which hold the board pivoting pin, and right, both keelbands are bent and bulging out down in the area of the pivoting pin. And, to my dismay, there is now also pitting corrosion of the keelband in that area, which was not there when I launched the boat in April. The two parallel stainless steel keelbands are what -only- holds the centreboard in place, and from sinking out of the cboard case and boat towards Nirvana. Rotting keelbands, I find that shocking, my boat is just a few years old, and spent most of that time in its shed, and in Rossiters Boatyard in Christchurch.
And no, there is definitely no electric current nearby my boats mooring, this is a remote tidal creek on the South coast of Ireland.
More pitting corrosion on other boats also? Wrong stainless steel unsuitable for seawater?
A repair, and a longterm reliable solution must be found.