November 1997
His and Hers
Recently re-designed products from Nottingham valve makers Sherwood Scuba include BCs for the male and the female of the diving species.
John Bantin's friends tried the Luna and the Achieva.
WhAT is Sherwood? Something to do with Robin Hood or Nottingham Forest? No. Sherwood is one of the world's foremost manufacturers of oxygen valves for medical purposes. It is part of an American corporation that also makes valves for use with chlorine, nitrogen and other more esoteric gases. In this area Sherwood says it has 80 per cent of the world market.
Sherwood also makes valves for scuba diving, and is well-known in some parts of the world, but it is only just starting to penetrate the British scene.
The manufacturer has suffered as a result of low-profile marketing of a product range that was in dire need of modernisation. Now, with a more aggressive approach to marketing and a number of new, recently-redesigned products, Sherwood Scuba (based in Nottingham, naturally enough!) plans to redress matters.
The Sherwood Scuba Luna is a BC designed with women in mind. Made in the USA, it comes in small sizes with a shoulder and front strap layout, which bears in mind that ladies are not usually flat-chested.
It has a hard backpack with an easily detachable cushion for those who may be using it without a neoprene suit; a single cam-band and a hard-shaped tank grip; two accessible self-draining side pockets; and a comfortable cummerbund with Fastex buckle.
Air is dumped by pulling the corrugated hose to operate the shoulder dump, and there is a separate dump valve at the lower back operated by a pull-cord. The integrated weight system is suitable for up to 6kg of lead in two packs of 3kg - one each side.
These weight pockets are positioned towards the back of the BC, which is ideal for use with a more buoyant aluminium cylinder, but might lead to a more upright stance in the water when used with more negatively buoyant steel. Six kilos might not sound much, but it is about right for a woman in a wetsuit. It is obviously not intended as the only weight when used with a bulky drysuit.
Emergency release is obtained by pulling separately on two yellow grip handles at the front of the jacket. This rips open the Velcro parcels containing the weights, and lets them drop. We thought it best to do this with opposing hands.
The Luna BC was supplied for us to test in size M (8) so I enlisted the help of a friend who had only four dives to her credit before she embarked on a week's diving with it.
New divers often have lots of problems with their equipment. A classic is the BC that seems to fill with air without any prompting, sending the wearer helplessly to the surface.
I heard not one word of criticism of the Luna during its week of use, which suggests that it suited her perfectly. No news is good news!
I meanwhile tried the Sherwood Scuba Achieva, a very conventional BC.
Similar in many ways to the Luna, it does not have an integrated weight system, but does have bags of lift and capacious self-draining side pockets with angled entry. It has a couple of small stainless steel D-rings, plus two plastic ones and a female Fastex connector for those accessories attached to a 25mm-width webbing lanyard and a male Fastex buckle.
As a confirmed wing-user, I disliked the way the air was free to move around in the conventional BC single bag, but used the BC without any grief.
Both BCs have a maximum lift of 14kg in size M and are available in sizes XS (6) - XL (14). The Luna costs £249 and the Achieva £240.
Sherwood 0115 9458634
Mares MR22 Abyss Ruby
Save money on a regulator (later)
When Mares produced the MR22 Abyss regulator, it was aiming at the top end of the market. It was a very expensive item and, for those who really wanted to spend money, it was also made available with titanium plating instead of conventional chrome.
When it comes to something as important as breathing, it seems that divers are willing to pay the extra, and the MR22 Abyss has become a runaway success. Also, it has a proven record of reliability, with Mares receiving fewer than 0.1 per cent of warranty claims on sales, even in the consumerist USA.
When a manufacturer has made a product that really works, it has a great incentive to keep ahead in the R&D department. I would have thought this nigh on impossible with the Abyss, but Mares has succeeded with the Mares MR22 Abyss Ruby.
The Ruby has the now-familiar MR22 first stage with two hp and four mp ports, which allow the hoses to route off in the most convenient way, but the poppet seat of the valve is made from urethane plastic with an actual ruby gem stone set in it.
For the same reason that jewels are used in expensive mechanical Swiss watches, this allows virtually no wear and tear. An average sport diver will never have to replace it, and a busy professional is expected to get at least four years of use without any servicing needed. Equally, it is said to resist oil or grease and any form of corrosion.
There will be an even more expensive titanium-plated version available next year. Titanium is much more resistant to corrosion than chrome, although it must be pointed out that a titanium-plated regulator stored in damp conditions will grow an unsightly type of verdigris. Mine does this but the verdigris vanishes as soon as it hits the water.
The second stage of the Abyss Ruby is an amazing bit of retro design. It looks like it came off the carburettor of a Harley-Davidson.
It uses a lot of metal and therefore has good heat-sink qualities - good news for those who dive in cold water. The front reminds me of the perforated zinc they used to sell
for the windows of larders (sorry, if you are under 45 - you won't have a clue what I'm talking about!).
This design breaks up water flow caused by currents or fast body movements (such as when using a DPV) in order to prevent the uncontrolled free-flow sometimes experienced with high-performance second-stage diaphragms that are very finely tuned.
The Ruby has the usual Mares Dynamic Flow Control (DFC) design with wide-bore primary air supply to the second stage. It also has the Mares Vortex Assisted Design (VAD) with a by-pass tube that discourages those embarrassing out-of-control free-flows that you sometimes get when you first pass from air to water.
I found the Ruby's performance indistinguishable from the plain MR22's. Naturally, I assume it would take me years to report on its longevity - watch this space!
For nitrox users, Mares says that its new regulator is supplied nitrox-compatible, but not assembled in an O2-clean room. If you want to use high levels of O2, they suggest you have yours O2-cleaned beforehand. Personally, for mixes of nitrox 28-50, I would use it without a second thought.
The Mares MR22 Abyss Ruby costs £475, and is currently the most expensive regulator in UK shops.
Given the annual cost of a service kit and labour for an ordinary regulator (around £40 for most, and usually more for owners of other Mares regulators), the extra outlay now could save you money later. This is if you do a lot of diving or hope to continue with the same regulator for more than five years.
Blandford Sub-Aqua 01923 801572
O2 Dive Data Card
Bruce: 'what a card...'
The O2 Dive Data card is a linear table for use in the partial-pressure blending of nitrox. It lists a set of arithmetical factors that are needed when you want to calculate a mix of pure oxygen and air to obtain a predetermined percentage of O2. They are also used for changing an existing nitrox mix, or for blending with limited O2 pressure.
Because you need to be qualified to blend gases in this way, I sent the card to a nitrox facility. Bruce Cochran at Kent Diving looked at it and told me what he thought:
"I don't see the point of it. In order to be qualified to blend nitrox we already have to know the information available from this card. The general public would not want to blend nitrox at home, so I don't really see a market for this product."
The card bears a caution that includes the words, "Attempting to blend or dive Enriched Air Nitrox mixtures without proper training could result in injury or death." I see what you mean, Bruce.
O2 Dive Data 01733 328987
Suunto SK7 Compass
Tilt? Forget it!
I used to teach underwater navigation to would-be BSAC Sport divers. Well-practised walking about on land with their compasses, my student divers would be set the task of swimming underwater to a shot-line and buoy, and then back to the boat. I always did this within the confines of a bay and sent each pair in with an SMB so that I could keep track of them.
Why was it that, on nearly every occasion, I had to sit and watch while they set off on an entirely erroneous course, and had to wait until they ran out of water before they realised they were not using their compasses correctly?
Tilt. It seems that, without the reference of dry land, divers have difficulty holding a compass horizontally. If the compass pointer is not allowed to swing freely, it will jam. My students always seemed to be seduced into following a compass that was steady - but it was tilted and so jammed. The Suunto SK7 compass has been designed so that its pointer, or compass card, will swing freely even when the unit is held a long way from the horizontal position. This makes its body by necessity a little deeper than some others, but it makes the user less susceptible to tilting it beyond the point at which it works efficiently.
Beside the usual rotating bezel and marker, it has a very large sighting window that allows it to be used at eye level. If my student divers had been equipped with such an easy-to-use compass, they might have spent more time doing real diving.
The Suunto SK7 Compass in wrist-mounted form costs around £50.
Blandford Sub-Aqua 01923 801572
SeaDog USA Bonafide T-shirts
T-shirts: an expert speaks
In my book Americans are excellent at making three things - extravagant musicals, enormously edible steaks and cotton T-shirts.
Many of the T-shirts we get in Britain come from the factories of the Far East, where profit margins are sometimes regarded as more important than the longevity of either the products or the workers.
They are usually flimsy, badly cut, poorly stitched, shrink to four sizes too small in the wash and, if you are really unlucky, impart colour to all your other clothes. But they are cheap. US T-shirts are none of these things, and seem to last forever. But they are more expensive.
I have owned T-shirts from virtually every production area in the world, and consider myself something of an expert! So does the distributor of the Bonafide range from Sea Dog USA. So it sent me a T-shirt to try.
Just as I would have expected, it has all the attributes and none of the flaws listed above. It also costs £22.99! Available in iris blue, raspberry, green, olive or tan, it comes in sizes American XL and M.
Markat 01935 815424
The most expensive regulator on the British market, the Mares MR22 Abyss Ruby (above) costs 475. When it comes to something as important as breathing, divers are willing to pay extra...
Top: second stage of the Mares MR22 Abyss regulator, the front reminiscent of the perforated zinc John Bantin remembers seeing on larder windows!
Below: Suunto SK7 wrist compass takes a major kink out of underwater direction-finding.
Appeared in DIVER - November 1997
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