Wednesday, July 2, 2008

Which Dry Suit ?

Here in South Africa the diving dry suit is more the exception than the norm. Well, for most divers. For those of us diving caves (or Cape Town or long decompression) a dry suit is a must. With the slow adoption of technical diving more and more divers are starting to move towards dry suits. The question is which one ?

For those of you who are reading who are not quite sure what a dry suit is… simply put it is sealed suit that prevents nasty cold water from ever reaching/ touching your skin (well ok, not your hands and your head, although you can get dry gloves and hoods but that is a bit of overkill in Africa). It does this through the use of seals that prevent water from entering the suit at your neck and wrists.

There are many brands of dry suit available to a diver, but only these tend to fall within two main types, a shell or membrane suit or a neoprene suit. Each 'type' has its own set of pro’s and cons, not the least of which is price (indeed price is often the most important factor when selecting a suit).

Shell suits are so called because they are made of a thin, strong and durable material that creates a shell around the diver. This resembles a hard wearing membrane and is made up of layers. For our use the only way to go is a tri-laminate membrane suit as the bi-laminate is just too thin and prone to breaking (a membrane dry suit is worthless if it leaks). As the suit is a thin'ish membrane there is little insularion (unlike a wet suit). The intention is too keep the water out so with a membrane suit inners must be worne to provide warmth. Without the inner (think portable sleeping bag) diving in cold water is akin to standing in a gale with a dry mac on…i.e. cold!
There are a number of advantages to a membrane suit :
- They are cheaper than neoprene (especially crushed neoprene)
- They do not change their thermal insulation and buoyancy properties with depth (neoprene compresses and so becomes less effective)
- They are versatile as you can change your inners (and so your warmth factor), moving from a thin inner (or even just a track suit) to something hectic and more appropriate for arctic conditions.
They do however have disadvantages:
- They are not as flexible as their neoprene cousins, so if you are dressed up for warmth reaching fins can be a problem
- They have little to no thermal insulation properties so if your suit floods, you stand the chance of freezing unless you have some hectic inners or a heating system (they do exist)


The neoprene counterpart comes in two varieties, normal neoprene and of course the deluxe and ultimate... crushed neoprene. The big difference with a neoprene dry suit is that you tend to use them without inners (unless you are using crushed neoprene of which the DUI is the only choice).
Advantages of neoprene:
- They have in built thermal insulation like a wet suit so if you have a loose fitting one (not normally the case, they normally fit tight like a wet suit) you can add warm inners and so create the ultimate suit for long, cold stays
- Because they are neoprene, if you flood your suit you stand a better chance of heating the water up and surviving
- They are more flexible than a membrane with more give
Disadvantages are:
- Unfortunately unless you are diving crushed neoprene, you lose a good part of you insulation properties at depth thanks to compression and you end up with buoyancy issues
- Price! Crushed neoprene suits will make you weep and even normal neoprene is more expensive than a membrane

So which to choose ? I did my world record using a Scubapro membrane suit. Nuno Gomes prefers neoprene because of the thermal insulating properties. I have now moved to a DUI crushed neoprene but the jury is still out. There was nothing wrong with my membrane and the only reason I moved to neoprene was because my next dive will be over 6 hours and I need extra warmth (read on for the paragraph on pee valves). Most of the divers we talk to make their choice based on price, which means membrane (especially if they need a custom fit).
Once you have chosen between membrane or neoprene you still have to choose from selections like;

  • telescopic torso (a must as it gives you manoeuvrability, flexibility and comfort),
  • where the dump valve goes shoulder or cuff (shoulder is better as it is out of the way and high up on the suit, on a cuff dump you have to spend your ascent with your hand above your ear….kinda inconvenient)
  • and whether or not you want extra thigh pockets (yes, you do, they are damn handy)

Suits also come with back entry or shoulder/ front entry. To be honest, I still need help on the self donning shoulder entry suit but only with that last centimetre. Having said that, the self donning is still way easier to get into and out of than the standard and more common back entry which requires either a second person or some interesting antics as you try and ‘catch’ the zip tag and then pull it closed (or open) using a convenient protrusion (think cat scratching its back)

When it comes to a brand you have a wide choice, especially with the internet. Our recommendations are Otter or Scubapro (naturally) as these fit within our target price range (you do not want to know how much a DUI is these days). We find that we sell more Otter's simply because you can get a custom fit at a really reasonable price (and to my eternal regret, Scubapro does not make custom fit suits). Why is custom fit so important ? Well most divers actually battle to fit into the standard off the shelf cuts, especially if you are female and buying a male cut (which is often the case). Custom fit also means you do not have to spend your life with a size 8 or 10 boot when you feet are a size 6 (based on the off the shelf suit you had to choose to get your length and girth to fit).

Another question that is hotly debated is when to purchase a dry suit ? Normally divers leave the dry suit to last, well after they have bought their Liquivisions or VR3's. Which I find odd. You can always (and normally do) plan your dive on paper so a helium computer is a luxury BUT you can not easily unfreeze yourself doing those 2 to 4 hour dives in cave cold water. From a pure risk management view point maintaining your body temperature should be one of your primary and critical factors that you are managing. Being cold is just way more of a risk than having a snazzy helium computer that means you can cut corners and not plan on paper before a dive. My advice is always to get the suit before the computer (they cost more or less the same).

The final topic that does need to be discussed (and one that I am not going to blog about, I will leave that to Gerhard) is that of pee valves. This is a conversation that I really do not want to know more about and is exclusively an option for the male dry suit diver and yes, I am jealous. When I do a deep dive I have to wear incontinent nappies which last like twenty minutes after which I am wet and cold . The guys fit their condom catheters and spend a blissful 4 hours warm and more importantly dry.

Would I ever go back to diving wet ? No way! I have only ever been too warm in a dry suit once and compared to being almost permanently cold and unable to warm up after repetitive dives I think the warmth of kitting up in mid summer is a small price to pay. Admitedly sea dives take some getting used to these days as it is harder to get back into the boat because I have a power inflator on my chest that catches me as I try and get in but then again, sea dives are not really on my agenda much so I guess I can live with the inconvenience. If you are a technical diver my only question to you is, why are you not diving dry yet ?