EXTRA
January 2000
HEAD to HEAD:
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EXTRA
January 2000 HEAD to HEAD: |
   
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The two US regulator makers Sherwood and Dacor have had a low profile in Europe until now, but Dacor's takeover by Mares and Sherwood's recent association with a more market-active distributor look set to make their products more acceptable to British divers. The £209 Dacor Viper is a budget-priced regulator for those who like the Viper TEC (around £250), but cannot justify the extra expense. Like its sibling, it has a diaphragm first stage and a lightweight second stage which incorporates a side exhaust. It weighs in at just over 1kg (its second stage is a mere 175g), where some are closer to 2kg. This unit confers all the advantages of a regulator which can be used either way up, right or left-handed. The right-handed-only, but similarly priced Sherwood Blizzard (£200) weighs only a little more. It has a piston-type first stage of a design unique to its make. The Sherwood "dry-bleed" system keeps the internals dry by maintaining a positive pressure and a tiny amount of air is permanently bled off in a minute stream of bubbles. Well-intentioned companions will insist on telling Sherwood users that they have an O-ring about to blow! Five medium-pressure ports (including two primary ports for the hoses to second stages) and two high-pressure ports are arranged around its chunky barrel. The Viper shares most of its features with the Viper TEC (Diver Tests, September 1998), including Mares' patent Dynamic Flow Control, which minimises the drop in interstage pressure during inhalation, and Vortex Assisted Design at the second stage, which removes the need for a venturi plus/minus control. The Blizzard also manages to do without any knobs or levers on its second stage. The Viper's obviously Mares-made first stage has two hp and four mp ports, including one special DFC port for the primary second stage. It can provide a maximum flow rate only slightly inferior to that of the Viper TEC, but lacks the super-flow hose to the second stage. It does not have quite the ability of the TEC to "beat the machine", but I found it less prone than the TEC to deliver an uncomfortable gush of air at positive pressure at the end of a big inhalation. When performances were compared on the ANSTI machine, the Blizzard's looked less dramatic than that of the Viper. However, this translates into a supply of air delivered in a much more comfortable and less "noticeable" way. If you wish your breathing to be as natural and non-distracting as possible, the Blizzard wins hands down. If you demand your air in a gush, you will be happier with the Viper. The Blizzard's second stage is small, with a purge hidden behind a soft all-encompassing front shroud. To avoid the problems of exhaled air obscuring the diver's view, it has a wide exhaust port. Mouthpieces make a difference to performance. Regulators are tested on machines without the mouthpieces in place, but I believe that those which allow you to form only a small orifice with your mouth can ruin an otherwise excellent performance. The Blizzard comes with what I at first believed to be the most comfortable mouthpiece available. It sits well back in the mouth and holds the jaw in a position that does not inhibit air flow. However, I can see that some would think it touched their tonsils, although it could easily be trimmed back. After an hour or so with it in my mouth, it began to get on my nerves. The Viper is so light that its otherwise slightly small mouthpiece is not a problem. Not content with my own judgment, I went for a second opinion to Dr Richard Webster, a Yorkshire GP, experienced diver and fellow-passenger on a Red Sea live-aboard. He normally uses a Poseidon. After using both, he thought that the Blizzard was more agreeable all-round, though he felt that the way the wide exhaust-tee sat on his chin was a little annoying after a while. He found the delivery of air from the Viper far too turbulent by comparison and said the bubbles exhaled from it impaired his view. As its name implies, the Blizzard is Sherwood's coldwater-spec regulator. An indicator of this is the heat-exchanger positioned at the junction of the hose and second stage. The hose bears two plastic rings - one of which is removed by the service technician each time a price-included-with-purchase service is performed. The diaphragm lever of the Blizzard and the Viper's second stage are PTFE-coated to avoid a build-up of ice crystals that might cause sticking and inhibit action. The Blizzard uses a similar coating on other parts and has internal fins to capture some of the heat from the exhaled air. One aspect I disliked was the way the Blizzard released thousands of tiny bubbles from its dry-bleed system. These added to other water-borne detritus, which can be a problem for an underwater photographer. However, this regulator is a good all-rounder which should not let you down on a winter's day in fresh water. The Dacor Viper is a bigger performer, although it might not have quite the total performance at depth preferred by those who like to push the envelope. Because of its light weight, it is sure to become a favourite with those who stay within the more normal depth range for leisure divers and do their winter diving in sunnier climes. Try it before you buy it. The Dacor Viper costs £209, the Sherwood Blizzard £200. |
   
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