Athwartships vertical surfaces, yes. All vertical surfaces, no!

"SAIL LOCO" wrote in message ...
Just to reduce the ignorance level around here, in a GRP vessel
the ceiling is comprised by the area between the sole and the
overhead. The overhead is that area which is over one's head
and parallel to the sole.

Vertical surfaces on a boat are called bulkheads.
S/V Express 30 "Ringmaster"
"Trains are a winter sport"