Brian G asked... > What is a boat drain?
I'm intrigued by this one! It's not mentioned in my OED (compact edition courtesy of Mike Stevens). As you say Google doesn't help in general. It does find references to "Boat Drain Church" near Bradford, Florida and "Parks' Boat Drain" in Ireland on South Lough Neagh... http://www.slnra.org/webpages/boatdrain.htm Looking at the linked picture it rather looks like somewhere boats were hauled out. Glen
