Originally Posted by degidio
I've looked at a few pics online and we like many features of the Mainship. Can anyone tell me the extent of the problem? Is this a systemic problem with the manufacturer, is this normal wear. Is it a plywood deck that's rotting? Would a survey point this out?
Mule described the basics, how and why. I'd add it's more like part of boating, not so much attributable to any given manufacturer. Certainly some are better than others at installing (and sealing around) deck hardware. At the same time, coring is commonly used throughout the industry to reduce weight, so the problem could arise with many makers.
If you find a model you like (any brand) some will be in better shape than others. When you find the specific boat you like, inspection for such issues would be normal.
FWIW, our '87 Mainship III had no such issues, at least during our stewardship.