Never bothered with 'em.

They say drinking salt water drives you insane, but that's a myth!!

Ha ha ha ho ho ho hee hee hee, I'm a little teapot, look at me!

Over hydrate before you go out, I try to sip as much as possible before I go, little sips every few minutes for half an hour before you go out. Not one big gulp seconds before.
I might pee my wetty 4 times in 3 hours but I don't get thirsty on the water.

Havnt tried the camelpacks yet, but do a couple of runs, have a couple of sips of water (or mixed gaterade) leave ya drink bottle on the beach.

I wear a 1.5 ltr camel pack when I go formula racing and I re-fill it when ever I can. If you're drinking before you go out then doing a few hours in a session then you're not drinking enough water. Even drinking all that water (maybe 4-5 ltrs / day) and racing all day I still don't think it's enough to be healthy. Admittedly I'm racing between two and three times longer than the good guys (luckily the nickname slowie was taken). But I think with all the knowledge out there, not drinking enough is just plain silly and un-healthy. There's nothing worse than waking up the next morning with a hangover headache and not having had that much amber stuff the night before.

Jethrow

I used a Camelbak last summer and it worked a treat. Takes 2 liter's of cold water and has other pockets for spare rope etc.
I only use it on flat water but if you keep sipping while you are sailing it stops you getting thirsty. Im like Elmo, even if I drink a truck load of water before going out I still get thristy.
Just remember to rinse it with fresh water so the zips dont get sticky.
I think Dakine make a straight bladder model.
Definitely a good thing to have on a hot summers day and as Jethro says, being thirsty means you are dehydrated so keep up the fluids.
Cause then the cold frosties at days end taste even better

Here's another option I've tried:

You can wear a mesh bumpack/bumbag/whatever they're called (mesh lets the sea water out, clever eh?) and carry a few drinks, preferably in small cardboard cartons, eg milo, fruit juice, etc - that way you have a variety and get some energy too. It worked a treat - but here in Singapore one rarely stays out too long anyway so it's not so necessary.