We have lived aboard for three years now, we have a plastic salt container bought somewhere in the Caribbean and decant any old salt into it, never gets damp.
Mirrelle. Having been plagued with the same problem for years in small boats - last year I found a 'snap-lid' container in Woolies which is completely airtight and has solved the problem completely. I will try and find the name for you. Oh, the bliss of dry salt!.
A metal grinding assembly corrodes instantly, of course, so one buys a plastic one, but that does not stand up to hard usage
W H Bounds Ltd, USA have in their range of grinders, wooden bodied salt grinders with ss grinding bits and those mounted in the base of the grinder on a plastic plate. Have seen them for sale in a number of countries, so suspect easily found in UK. If I remember correctly, they have a lifetime guarantee.
We have a salt cellar with ceramic grinders which also carries a lifetime guarantee. Brought from John Lewis last year, so it's a bit early to tell whose lifetime they are referring to......
Cost an arm and a leg, but seems to be working OK so far.
I got a plastic salt and pepper set from the pound shop in Gosport. Both salt & pepper have a lid that twists to close the holes. I half filled it in March and added a teaspoon of uncooked rice. No problems so far!
The closing lids are also handy when some idiot in a mobo throws everything off my table /forums/images/graemlins/frown.gif
Tried the rice ploy - works for a short time.
I now use a salt mill, when not in use I keep it in a snug fit air tight container. Works a treat, even long term.