Ok, here's an update to my previous post above. I did a bit more research as I myself have been trying to decide if my Oneill 4/3 surfsuit which keeps me so toasty surfing here in Monterey Bay would be suitable for my tropical dive trip.
The information I'd managed to wrestle out of the employees at the Oneill shop in Santa Cruz right next to the Oneill headquarters wasn't sitting well with me just because of the somewhat bewildered and less-than-knowledgable sales staff who had to resort to looking at a catalogue to answer my questions about neoprene. They were basically clueless about neoprene which was really surprising given that Jack Oneill invented wetsuits in the 50's and the old man is still around and in charge. I'd been surprised that at what I thought was some pretty piss poor training by Oneill. Well, it turns out that that big shop with the big Oneill sign on it isn't actually owned by Oneill- someone licenses the name from them. Makes sense I guess if you're a wholesaler of surf gear to surf shops you can't really go and compete with your customers can you?) So, that's why the employees I spoke to don't know Richard about neoprene and were WRONG about there being no difference in surf vs. dive suits. There's a world of difference.
The neoprene itself CAN be the same, but, dive suits generally have a denser neoprene blend. This density adds some durability as it is less easy to tear, but, chiefly the more dense stuff retains it's characteristics (read warmth) better after repeated compressions.
The real difference is in the nylon or other fabric weave that is layered over the neoprene on the inside and outside. The strengh, thickness, and resistance to abrasion and tearing are what really set dive suits apart. Surfers realy only come into contact with eqipment (a board) in a couple places (butt, chest) so most of a surf suit can be light on the nylon layer cause there aren't a lot of rough edges to rip and tear at fragile neoprene. This light stretchy layer gives surf suits more stretch. Stretch is good if you're surfer, but, not so important for the relatively more sedate motions of divers in their element.
Dive suits on the other hand have burlier nylon because they have to contend with belts, buckles, boat gunwales, backplates, straps, etc etc. Your typical surf suit will be beat all to hell from 50 dives. Supposedly dive suits also have more attention paid to the seals at the neck, wrist, and ankles, but, I know my Oneill surf suits are meant to be pretty damn snug and indeed dry and they look and feel just like the ones on my Oneill dive suits.
I trust the fact that Jack Oneill basically invented wetsuits back in the 50's and pioneered many of the innovations that are standard in the industry like glued and blindstitched seams. I own 6 Oneill wetsuits- 3 for surfing and 3 for diving, one I bought yesterday. But, that being said, it seems like any manufacturer whose core business is wetsuits makes a good suit.
What is important are the fit, first and foremost, as the fit determines if there's going to be any water flushing in and out of the suit, something you do not want as the thin layer of water trapped in the suit is what warms you. Second is the construction. Fit should really be done at a shop as it's easy to get it wrong. As for construction, first, it has to have those glued and blindstitched seams or, better yet, fluid welded seams (no thread at all!). If not, the stretching and pulling you do to doff and don will eventually widen all the holes that flatlock stitched suits have and what began as water wicking through to chill you a bit will become more and more annoying and chilling, lessening the lifespan of your suit and your dives. Sure, it's cheaper right off, but, you'll pay in the end.
(The owner of Aquan Sports in San Carlos, CA was a great help in understanding the surf suit vs. dive suit issue and I'm mostly paraphrasing him here when i compare the two- Thanks Vince!)
