John Bantin fancies himself in an undersuit from a new range by Northern Diver, which comes in three different levels of thermal insulation
Keeping warm is a prerequisite of good diving technique. Besides the obvious problems relating to hypothermia, simply getting chilled is enough to cause a break in concentration which could lead to mistakes.
Luckily, we are well served with a wide choice of drysuits in this country, and it is only necessary for us to choose the right amount of thermal insulation to wear underneath.
Northern Diver have produced a new range of undersuits in three different thermal ratings to cater for all manner of diving situations.
In each suit, the outer layer is a slippery Teflon-derived black material. They are water-repellent and wind-proof, but unlikely to cause you to sweat uncomfortably because they are breathable.
The SPX, the lightest of the three, features a box pleat at the back for ease of movement. I found this undersuit excellent for use over my jeans and T-shirt and under my 4mm compressed neoprene ND Divemaster drysuit last summer, in Britain. It would also be suitable alone under a membrane drysuit in the northern Red Sea during the winter, for example.
Next in the range, there's the slightly thicker SPX Pro. This has a vertical parallel quilting of double-sided fleece and an elasticated back waistline, reinforced spine and kidney sections, and knee and shoulder pads.
Similar in look to the SPX Pro and the thickest of the range, is the SPX Thinsulate, with a hexagonal quilting of double sided fleece and a layer of 'thinsulate' material sandwiched between the inner and outer linings. This mixture is claimed to absorb very little moisture. This claim was borne out when I decided to put mine through the washing machine to remove the talc and other evidence of heavy use before photographing it. It dried almost instantly. In use, both in and out of the water, I found it very warm indeed, in combination with my drysuit.
Normally I'd wear this thickest undersuit with my trilaminate membrane drysuit. Recently, I found its slippery Teflon coating enabled me to squeeze into my ND 4mm compressed neoprene Divemaster suit, and survive some particularly cold conditions, even if it did mean I had trouble bending down and my arm movements were a little restricted.
All three undersuits feature knitted and ribbed collars, ankles and cuffs, with pockets at the hips and left breast, and a two-way zipper for those moments of urgency after a long time in your drysuit. Most interestingly, these suits are supplied with a lower arm section made of nylon mesh to avoid any problem of the garment's outer material being drawn into a venting cuff dump valve and blocking it. I personally have never had any problem with this material with my previous (meshless) ND Teflon undersuit. The open-mesh arms do mean that the wind whips through when you're not wearing your drysuit over it, and you can get cold. Northern Diver was spot on in supplying me with suits that fitted. They are available in a wide range of sizes, but I suspect that the folks at the Wigan factory called up my rather awkward measurements on their computer and made the suits to measure. They can do the same for you at an additional cost.
Which thickness is right for you? It all depends on your build, your drysuit, the temperature of the water you dive in, and the duration you expect for a dive. Be advised by your dive shop or instructor.
Although the OMS dual bladder BC has the lift to cope with an overloaded tekkie, when not inflated it is held compact and streamlined by elasticated bungee cords.
Ocean Management Systems (OMS) - an American company which manufactures equipment for technical diving - has recently made its first foray into the UK diving market. The company sent me its wings-style dual-bladder BC. This came in a ready-to-assemble kit consisting of de luxe harness, backplate, tank bands and their valve arrangement for use with twin tanks.
My initial problem was to find a suitable pair of 8in diameter cylinders to twin up. This was because I had, unthinkingly, asked for stainless steel tank bands of 8in diameter. (They also do more useful, smaller diameter tank bands.) As a result, I tried the OMS kit with dumpy twin 12s and, with 24 litres of gas on my back, a slight over-capacity on the air supply side! Rigging took a fair few minutes and not a little muscle power. First, I had to fit the valve manifold; then, the tank bands with sufficient spacing to match the fixing bolts to the holes in the harness backplate. The dual bladder system is sandwiched between the twin tanks and a bulletproof-looking backplate.
I have to admit that the assembly was not easily achieved on my own. I managed to cut my finger in the struggle before enlisting some additional help. Mind you, it's not the sort of kit that you would take apart after every dive. I suspect that you might want to deliver the full works to the air station for refill.
Tekkies insist on doubling up on all their equipment, including the BC, and for this reason there are the two bladders, with rugged ballistic nylon outer covers, each with its own direct feed from each of the two independent regulators that fit the valve manifold. There is the facility to run the corrugated hoses for the direct feeds over either shoulder or to run them both over the left.
Now we come to the unique selling proposition of this particular item. Although the BC has more than enough lift to cope with everything an overloaded tekkie takes diving (I calculated more than 38kg), when not inflated it is held compact and streamlined by a system of elasticated bungee cords (or expansion/contraction bands as OMS prefer to call them).
You may have seen this in other brands of double-bladder wing-style BCs, but in this case the unfilled bladders are kept really tight. Added to this, the bungee cords can be adjusted by selectively removing some of them, to give trimable buoyancy. This is important to a diver who may be carrying an extra cylinder which otherwise might leave him swimming with a list to one side. The harness was supplied ready adjusted for someone with the ample frame of a typical burger 'n' shake American, not my more gazelle-like figure! Quite frankly, it was a pain to adjust. Not something you would want to let anyone else use, once set up for your own requirements.
There's a jockstrap with a Prince Albert-style ring which stops the whole lot crashing around your head when you tilt over and head speedily for the depths. There are also two bottom-of-the-bag dump valves in case you find yourself speeding back the other way. Air can be released from the number 1 bladder by either a shoulder dump or simply by raising the corrugated d/f hose, as with the number 2 bladder.
The J101G-M25 twin-valve manifold is a fine piece of engineering. It has a valve tap centred between the cylinders as well as the individual cylinder valve taps. It allows you to breathe all the air from both cylinders through either of the two regulator 1st stages which you fit, or keep the supplies separated. The connector to the 1st stage is either by A-clamp or DIN. You simply remove the centre part with a suitable hexagonal wrench to allow for the DIN fitting.
It's a modular system which can be built up to make a variety of tank valves both for twins and single cylinder set-ups. If you use a single cylinder (with a suitable twin tank valve set-up and two regulators) you can still use the dual-bladder BC with the aid of an OMS single tank adaptor.
The harness features both a waist band and upper chest strap which prevents the shoulder straps pulling apart and off the shoulders.
As I stumbled the few paces to the water's edge, I reflected that if I fell, nothing much would happen to the OMS kit. If only I too was built to such substantial specifications! The steel twin 12s weighed in at 30kg and the stainless steel backplate added considerably more.
There's no chance of getting stabbed in the back with this set-up. No, it's the self-inflicted hernia injuries which one has to look out for! A couple of twin 7s on 5.5in tank bands would have been more to my liking.
I had to come to terms with the fact that my willowy build is not cut out for technical diving. I regarded the seven harness D-rings for additional tanks with a certain amount of horror. If you've met Bret Gilliam, co-founder of Technical Diving International and former world record holder for the deepest dive on air (a man whose neck is thicker than any part of my body) you'll know why he's built the way he is. Solid as a piece of OMS kit. This stuff is for the serious diver.
The Northern Diver CNX200 drysuit comes in an uncannily thin 2mm compressed neoprene, and is claimed by its Wigan makers to be the most hard-wearing suit you can buy.
Northern Diver are well known for their neoprene drysuits. It wasn't so long ago that I reviewed their Reefmaster and Divemaster designs, made in American 4mm compressed neoprene. Although the folks at ND were dismayed that I reported that a little water always seemed to pass between my sinewy wrists and the neoprene wrist seals, creating an effect more like a 'damp suit', it didn't stop the Divemaster becoming my first choice for diving when water temperatures demanded it. What's wrong with slightly damp forearms when you're going to get a very wet head anyway?
The latest development from the factory in Wigan is the CNX200 suit.
This suit is made in an uncannily thin 2mm compressed neoprene. It's an American material finished with a heavy-duty, canvas-type lining. Northern Diver claims it to be the most hard wearing suit available, a claim which is hard to verify in the short time available to evaluate such an item. I can confirm, though, that the only occasion my previous Northern Diver suit let me down was when someone drove a sharp object through the chest. I wasn't wearing it at the time!
The thinking behind the 2mm compressed neoprene is akin to that of a membrane suit. In fact one can see that the makers are bowing to the obvious marketplace popularity of membrane suits.
Like a traditional membrane suit, it affords plenty of ease of movement, and, as with a membrane suit, you are reliant on an undersuit for thermal insulation. So what appears to be the advantage of a membrane suit made of this type of material?
Northern Diver have my measurements and the suit they made for me is tailored precisely to fit. Once I've got into it, it feels jolly nice to wear. I could wear it all day. However, getting into it is not so easy. It's fitted with a heavy-duty diagonal front zip which passes right over the left shoulder. It makes for a wide space to get into, and pulling the suit up over my legs and lower torso was simple.
However, pulling the shoulders of the suit and the neck seal over my head from behind was a bit more difficult. There is a certain amount of stretch and additional length in the body to enable you to do this, but ND do not allow enough to necessitate a tuck or braces. This makes the final part of the donning procedure rather dramatic, and causes a certain amount of anxiety among any well-intentioned onlookers. Once in, the front diagonal zip is hard to get started, because it is positioned so far over the shoulder. You have to ask your buddy for help. Consequently, I find this zip to have little advantage over the conventional cross-shoulder type which is available as an optional alternative. Other optional extras include a fly zip, and attached dry hood and neck seal combined.
Naturally, in ND tradition, the suit is finished in a bright red and black, and covered in radar and light-reflecting patches. The boots are 'sealed for life' with a hard sole and a comfortable lining which needed little more than one's normal day-to-day socks for comfort. Kevlar knee patches - slightly more attractive than rubber - and your name embroidered on to an exterior pocket, make the finishing touch.
The direct feed valve and constant volume (automatic) dump valve are Northern Diver's own manufacture and are positioned on the centre chest and upper left arm, respectively. An option is the ND blowgun inflation system, which is very handy to disconnect and use to inflate a lifting bag or a late deployment SMB under water.
So what is so special about the CNX200 suit? If it fits you perfectly, as did mine, there's less water resistance while swimming than there is with a more bulky, traditional membrane suit, but you have the same option to vary the insulation levels to suit the environment. It's about as sleek as a drysuit can get.
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