This is the third product recall this year from technical diving manufacturers. Already Halycon and OMS have voluntarily recalled their products throwing the entire technical diving equipment manufacturing industry in question.

In cooperation with the US Consumer Product Safety Commission, Dive Rite is issuing a voluntary recall on various Dive Rite Wings.

The Over Pressurization Valve (OPV) springs found on Dive Rite wings manufactured between June 2006 and October 2008 may rust and fail allowing the buoyancy compensator devices to leak. The wings may be red, blue or black in color and have serial numbers falling between 42000 and 72000. The following models are affected by this recall: Travel, Venture, Rec, Trek, Classic, Nomad and Super Wings It does not affect EXP or 360-branded wings. The recall does not affect lift bags, surface marker tubes or other Dive Rite inflatable devices.

Due to the serious implications of an OPV spring failure, consumers should stop using the recalled diving equipment and have the OPV spring immediately replaced by a Dive Rite authorized dealer or distributor.

More information can be viewed on their website.

by Marius Clore
Equipment and Technology Chair, NACD

Cave diving is critically dependent on lighting, hence the absolute minimum requirement of one primary light and two backup lights. The primary light must be sufficiently powerful both to signal appropriately and to view the cave, while the backup lights, which must be very reliable, need be only sufficient to follow the guideline out of the cave.

The advent of HID lighting has led to considerable improvements in both the quality of light and burn time over the older halogen lights. HID stands for High Intensity Discharge, and HID bulbs consist of two electrodes a short distance apart in a gas-filled chamber. A high voltage (low current) pulse across the electrodes creates an initial spark that results in the formation of a small plasma arc which produces a very broad band of high intensity light extending from the infrared to the ultraviolet.

In this brief article, I will summarize the basic features of HID lights, and compare HID lights in the 18/21W range from a number of manufacturers, including Salvo, Halcyon, Dive Rite and Sartek (see Table for summary of features and specifications).

In terms of components, an analogy between a HID light and a tank and regulator is useful. Every HID light comprises a battery canister, a battery, a ballast and a light head which are analogous to the tank, air supply, regulator 1st stage and regulator second stage, respectively. It is also worth considering that HID light usage should be considered in the same vein as air usage. Just as one turns a dive on 1/3rds, one should never plan a dive where the total possible duration of the dive is going to exceed half the burn time. Moreover, one should be conservative in this estimate since, in contrast to one’s air supply where one has a direct read out of remaining air pressure, it is impossible to know exactly what the total burn time is going to be, since this is obviously dependent on how well the battery has been charged (see below).

Given that HID lights are built from standard components, the variations in design are rather limited, and consequently, the choice of light is to a large extent a personal one based on preferences relating, for example, to the size of the canister, the packaging of the light head and the materials employed.

The canister. The canister should be robust and water tight. Salvo and Halcyon use Delrin, Dive Rite uses PVC and Sartek uses acrylic. Delrin is a more reliable material under extreme conditions, is not susceptible to cracking when dropped, and doesn’t become brittle in extreme cold. This may be important when diving in the Arctic, but under the environmental conditions found in Florida and Mexico, there is little to distinguish between the three materials. The dimensions of the canister are governed by the choice of battery pack configuration. The dimensions of the Salvo and Halcyon 9 Ah canisters are identical, while Dive Rites’ is wider, and Sartek’s is both wider and shorter. Indeed, the dimensions of Dive Rite’s wreck canister is the same length as the Salvo and Halcyon’s 13 Ah canister and only minimally narrower (3.5″ versus 3.75″).

The batteries. Modern HID lights are generally powered by nickel metal hydride (NiMH) rechargeable batteries. NiMH batteries provide the same energy (measured in Wh) as lead acetate batteries in a much smaller package (about half the weight and size for equivalent power capacity), they have a relatively long life with no cell memory, and withstand high charge/discharge currents. Generally, the nominal voltage of the pack is 12V and the total energy is given by the capacity in Ah times the nominal voltage. Thus a 9Ah 12V battery pack has a total energy of 108 Wh. If the ballast consumes 24 W (for an output of 18 W dues to losses), the total burn time can be estimated at 4.5 hours. However, the capacity of NiMH batteries is usually 10% lower than the rated capacity, yielding an actual burn time of about 4 hours. A 9 Ah pack can be built from either twenty 4.5 Ah 4/3 Fat A batteries comprising two strings in parallel, each comprising 10 batteries in series which easily fits into a 2.75″x10.5″ canister, as in the case of the Salvo and Halcyon lights. Alternatively, a more reliable pack in terms of obtaining a full charge (see below) can be built from a string of ten 12V, 9Ah D batteries in series, but the dimensions of this pack are quite a bit larger and can therefore only fit in either the 13.5 Ah Salvo and Halcyon canisters (3.75 x 10.75″).
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Sidemounting traces its roots to the UK, where cavers would strap small air bottles to their thighs, enabling them to traverse sumps — short, water-filled passageways that connected air-filled chambers, often far into a cave. Cave divers in the USA began adopting sidemount in the early 1980s, as a means of passing through bedding planes — cave passages that can be several feet wide, but only a few inches high.

Among the earliest adopters of sidemount in the USA were Wes Skiles and Woody Jasper, who recognized sidemount as the best way to explore cave systems such as Cow Spring and Jug Hole. (You can read more about the early exploration of Cow Spring on the NSS-CDS website.)

The rigs created by these early cave explorers differed from those employed by their British counterparts in that the cylinders used were substantially larger, and the divers wore them under their arms for better balance and body position. Still, until the mid-1990s, any sidemount rig you saw was going to be homemade.

Things started to change in 1995, with the introduction of the Dive Rite Transpac. Shortly after its introduction, Dive Rite’s Lamar Hires began offering a variety of hardware solutions designed to help users adapt their Transpacs for sidemounting. Still, in many respects, these solutions were only slightly removed from their homemade predecessors.

The real sidemount revolution began ten years later, with the introduction of the Dive Rite Nomad, a ready-made, out-of-the-box harness designed specifically for sidemounting. Simply stated, the Nomad changed everything.

Prior to the Nomad, sidemounting was seen as solely for cave diving, and solely for those few cave divers who “pushed” the tightest of passageways. With the Nomad, sidemounting became mainstream — something that any cave or technical diver could adapt to, and something with benefits that went far beyond cave diving.

* With the diving population’s aging comes a realization that prancing around in heavy, backmounted doubles may not be the healthiest thing past your 50th birthday. When the possibility of back, neck, knee and ankle injuries increases, it’s time to look for alternatives.

* Sidemount divers don’t have to wear their tanks to the water. You can carry cylinders to the water’s edge, one at a time — or roll them there on a standard hand truck.

* Sidemount provides true redundancy, free from the worries associated with catastrophic manifold failure.

* Without the manifold constantly hitting you in the back of the head, you can actually look up and see what is going on in front of you.

* For traveling technical divers, sidemount means they no longer have to be hampered by the lack of manifolded doubles at their destination. As long as there are single 80s available, tech diving is possible.

* Harnesses like the Nomad also offer an excellent solution for rebreather divers. Technical rebreather diving requires that users carry one or more open-circuit bailout bottles. By mounting their rebreather on a harness like the Nomad, rebreather divers have a means to carry those bottles in a way that is both streamlined and efficient.

No good deed goes unpunished. As validation of its concept, Dive Rite now finds competing sidemount harnesses made by Golem, OMS, OxyCheq and others. On the flip side, sidemounting has been recognized as a an alternative tech and recreational configuration by agencies ranging from the NSS-CDS to PADI.

PADI course director Jeff Loflin now offers a PADI distinctive Specialty Diver course for recreational sidemount diving, along with a corresponding distinctive specialty for instructors.

Despite its growing popularity, sidemounting is not a panacea.

* You most likely don’t want to jump off a dive boat with high freeboard wearing sidemount — nor do you want to have to worry about getting back on board. (Sidemount may, however, be the better solution for diving from inflatables.)

* When diving in places like the caves of Mexico’s Yucatan Peninsula, backmount is better suited for passing through the narrow openings between stalactites and columns.

Still, interest in sidemount is growing, by recreational and technical divers alike. In fact, there is a joke circulating in cave country about the veteran diver who shows up to dive with a much younger buddy. Looking over this elder’s highly Hogarthian doubles set up, the younger sidemounter remarks, “DIR? That’s so 90s…”