Last century's technology will chew up the Tiger and use the mast for a tooth pick. <img src="http://www.catsailor.com/forums/images/graemlins/smirk.gif" alt="" />

Tami - I'm a diver and a former chemist too. Here's a few things about neoprene:

- blown foam neoprene ala wetsuits does absorb some moisture; solid neoprene ala mechanical seals does not do so nearly so quickly. This has much less to do with the chemical structure of neoprene, than the construction of the material.

- sweaters work the same way as wetsuits do - air can get through your sweater, but the sweater traps a layer of air you've warmed with your body heat as an insulative layer. Air is not as conductive as other things. Although sweaters work to keep you warm (just wear one on a sunny day), you notice that cold air does still get through (why you still need a windbreaker on a chilly windy day). Neoprene wetsuits aren't nearly so permeable, but they are still permeable. This is less a physical property of the compounds in question than a mechanical property of their assembly.

- wetsuits do have pockets of air trapped in the foam 'matrix' - that accounts for bouyancy - but some water does get in through there. As Matt the Hobie guy says, a mast full of mostly air is more bouyant - that's because that air amounts to a giant air pocket/bubble, instead of lots of tiny ones.

Water molecules are rather small, just like, say, diatomic helium (think balloons), and they are capable of getting through very small "holes" in the 'matrix' of most solid compounds. You will notice that a helium balloon loses gas slowly, over a couple of days. That's because there are lots of very tiny holes - spaces between the rubber molecules - in the rubber of the balloon - and the gas leaks out very slowly through those holes, but it does.

Similarly, in neoprene foam, there are lots of tiny "faults" and voids in the neoprene, in addition to the air pockets. Water makes it's way in there. I think it's likely that neoprene that spends it's time at the top of a mast 99.9% of the time would stay pretty dry. But, Polystyrene (good old foam cooler material) foam is probably lower density. That stuff is also water-permiable, BTW. IIRC, the only mast float I've ever seen, on an Aqua-Cat, had a plastic skin around a polystyrene core - the skin helped provide mechanical protection, while the core provided bouyancy.

Finally - that's a great avatar.

Portrait?

Good science about neoprene, up until the [color:"red"]"diatomic helium" [/color] comment. <img src="http://www.catsailor.com/forums/images/graemlins/confused.gif" alt="" />
Perhaps it can be found near Cap'n Kirk's dilithium crystals. <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

diatomic == di-atomic == two atoms bonded == He2

http://en.wikipedia.org/wiki/Diatomic

Helium is an ideal/inert gas, so, truthfully, He2 is not really stable - you have to pop some serious energy into it to get it to form, and it will quickly decay from that state back to a lower-energy (2)He (unbonded atoms). H2 is what was in my head, but then I though, nobody uses that anymore (at least since the Hindenburg!), so it would be a poor reference.

I should've picked a different (and better) example. H20 is a much larger molecule/structure than a simple He atom. Nevertheless, I think the explanation still stands and is completely valid.

I'm sure the mechanical engineers immediately thought of a mechanical seal, not unlike, say, the rear main oil seal on the crankshaft of your car (though neoprene pretty much rocks for all sorts of mechanical seals plenty of which are "watertight"). Because Water (H20) and oil (hydrocarbons - C(n)H(2n+2)) are much larger structures, they don't seep through as quickly.

The real point of all this is: the bouyancy of the wetsuit is due to the air bubbles in the foam. The same properties make it susceptible to absorbing moisture. The older the suit, the more it will absorb, due to UV damage (breakdown of the neoprene) and mechanical breakdown (the little bubbles get broken open).

Can they be smoked?

Judging from your pic... somebody has???? <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" />

<img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" /> <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" /> <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

[color:"red"] "Helium is an ideal/inert gas, so, truthfully, He2 is not really stable" [/color]

Right, it's NEVER been seen under terrestrial conditions, ever. You're right about He being small and a ballon is porous to it.

However, your comment about H2 not being used anymore, here's a bit in use. <img src="http://www.catsailor.com/forums/images/graemlins/cool.gif" alt="" />

Nothing like a little excess to make a point! <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />

Clayton

Well, ok, not in use for balloons...making water - that's some serious exo-thermal action going on. For real oxidation.

He2 has been seen in some labs on earth that I've been in, but, yeah, not in ambient conditions.

Actually, the website on fiberglass delamination/blistering has a good explanation of this notion too. We'd still consider our hulls "waterproof".

Beating a dead horse no doubt, but I do NOT believe neoprene absorbs water. It's rubber. The reason your suit is full of water is because the cloth bonded to the neoprene holds water. My newest wetsuit, a prolimit windsurfing suit, is entirely smooth skin on the outside. Very nice as far as evaporative cooling is concerned because there is no cloth holding water (it is however very susceptible to abrasion).
Many Drysuits have been made of neoprene (like back in the 80's and 90's). They look just like wetsuits, but with waterproof zippers. There are two reasons your suit gets wet inside- because you sweat and because the suit leaks. If your suit has waterproof glued and taped seams and a waterproof zipper, it will let very little water in.
Getting water in the suit is actually a bad thing. The reason a wetsuit has to fit tightly is so that a minimum amount of water gets in. The more water in the suit, the more water your body ends up heating- the less body heat retained.

sm

try this experiment.

Weigh your neoprene wetsuit. Go sit in the water for a hour. Get out of the water. Shake the water off the suit. Weight it again.

report your finding here.

Doesn't Hobie use a glued on neoprene anti-slip panel along the tramp frame? Does that feel spongy or water-filled?

Remember those thin neoprene bikinis back in the 80's? They were pure rubber, very thin with no fabric backing. They never seemed to get soggy. In fact, they seemed pretty hot at the time! I doubt if what looked good then looks as good now. See attached.

Your my kind of scientist David.

I sure didn't need that image today! <img src="http://www.catsailor.com/forums/images/graemlins/crazy.gif" alt="" />