I was in Greenwich England at the British Maritime Museum when I discovered the true meaning 
of the nautical term Hull Ceiling. The museum is incredible. As an island nation, England has such an amazing maritime history and if ever you are in London with time to spare, go to the museum in Greenwich. I found myself wandering the museum for hours and until a guard told me it was closing time. I thought I had only been there for an hour or two. I had in fact been there for an entire day. Any way, back to hull ceilings.
In Greenwich I was aboard the famous Tea Clipper Cutty Sark She is permanently dry docked at the museum. Tea clippers brought tea from China to the markets in London and Europe. The first ships that arrived got the highest prices for their prized cargo and so a fleet of fast clippers was born to serve the tea trade. Tea doesn’t like to get wet (until it’s time to be drunk of course) and so these wooden vessels had to be as water tight as they could be. In the interior of the clippers was installed a secondary hull or “hull ceiling”. Any water or moisture that made it’s way through the exterior planking of the hull came to this second skin and simply ran or dripped off to the bilges. The hull ceiling exists in Sabre motoryachts today but today it is in most part cosmetic
We make up ceilings by laying strips of ash batten face down on a bench. W
e then tape and fiberglass the back side to tie the battens together into a large sheet, As we prepare to install the hull ceilings we place stand off blocks on the hull side with adhesive and then attach the ceiling to these blocks. By doing so we create an air space between the hull and the yacht’s interior. Any dampness or moisture created by temperature differentials is trapped between the hull and the ceiling. That keeps the interior dry and comfortable.
And yes we do like a spot of tea from time to time.