I was just thinking about the incredible lighter then air craft produced by

the Germans prior to WWII, and how they even had swimming pools in them. Of

course, the water was ballast that could be dumped in an emergency over

land...and I believe lead was dumped when over water (thus no complaints of

bombing)

Looking around, I discovered early attempts at developing a skin for

rigid airships involved the use of zinc. although cheap and light it just

didn't have adequate strength so that avenue of research was abandoned.

I guess that pretty much proves that you can lead a zeppelins water but you

can't make it zinc.