TEK-DPV
As appeared in Advanced Diver Magazine ,
Issue 9, p60-61.
For decades the warm, clear springs of North Florida have enticed
explorers to push their equipment to the limit. More often than
not, the cave extended well beyond where their equipment could
take them, resulting in an active culture of innovation. With the
recent popularity of technical diving, the results of this
tradition can be seen throughout the world whenever a stage
cylinder, manifold, canister light, or backplate or even a
diver propulsion vehicle is used.
Over the years many types of underwater scooters /DPV's have been
used to ease the drudgery of swimming long distances with a heavy
equipment load. Ride-on style scooters (such as Farallon and
Aquazepp) previously were the only scooters with depth capability;
but the tow-behind Tekna which debuted in 1985, is now
regarded to have a clear edge in motor/propeller efficiency,
maneuverability, and ease of operation.
Furthermore, divers needed a tow-behind scooter that had the
added features of depth capability and longer burn times. It was
fairly simple to build a deep rated structure for the tekna motor,
using readily available schedule 40 PVC pipe and PVC plate.
That design has been fundamental to the recent increase in
Floridian record breaking cave dives.
Two years ago (2000), Submerge Inc was started to develop a
state-of-the-art underwater scooter framework with the goal of
taking the concept several steps forward. The objective was to
as simple as possible in the scooters design. The UV
(underwater vehicle) scooter is made of almost indestructible
polyethylene, with no parts molded or glued.
The hull is 5/8" thick, yet is not heavy, as the material has a low
specific gravity compared to PVC or aluminum. Internally,
bulkheads of 1" thick polyethylene and 3/8" polycarbonate provide
the strength to withstand 300 or more feet of water. (update: UV
scooters have been to over 600 feet deep).
Marine grade aluminum is used for the motor compartment to add
rigidity to plastic sealing surfaces, and to withstand the heat dissipation
of the direct drive 24-volt permanent magnet DC brush motor.
Efficient design enabled the number of components to be reduced
by machining out of a single block of material. The main hull has
only 2 points that can leak and these are sealed by large section
o-rings (1/4") which are less effected by small amounts of
contaminates or small surface scratches on sealing surfaces.
All 3 scooter sizes, which use the identical nose and motor end
sections, have the batteries placed in a way that partially compensates
for the torque of the propeller, reducing diver fatigue. Additionally,
as the nose and tail sections are identical, it is easy to change the
battery and hull sections to any of the 3 available sizes, in minutes,
with no tools.
An important advancement was the new design for the handle.
All previous handles have been designed for 2-handed operation,
with the handles at the 3 and 9 o'clock positions. Experience has
shown the ideal method is to use a tow rope, rather than be pulled
along by both arms, and to use only 1 hand to guide or "fly"
rather than muscle the scooter; keeping the 1 handle at the 12
o'clock position. In the past this meant a contorted positioning of
the hand, as the handles were not designed to be used in this
position.
UV scooters are the 1st to incorporate a motorcycle style handle,
which is ergonomically correct for single-handed operation at the
12 o'clock position. The first inch of the handle is a trigger which,
when rotated against a spring loading, moves a magnetic reed
switch/relay circuit that activates the scooter. This method of
activation requires no through hull penetrations, and, therefore,
no point that can leak. A thumbscrew can be used on this trigger
to offer a cruise control feature, or when tightened, a lock off
feature. An added benefit of this handle is the elimination of many
small moving parts made necessary by previous designs.
The motors used in the UV scooters are quiet compared to many
other makes of scooters, which use a noisy gear reduction drive.
Previously this was just an annoyance, but with the advent of
closed circuit rebreathers, this has turned into a safety feature.
Many divers report they are unable to hear the oxygen addition
valve fire when using other makes of scooters. This is vital to
safe closed circuit rebreather diving. Of course, a noisy scooter
destroys the serenity of silence found with a rebreather.
Scooter diving is not new. But it can add a level of enjoyment to a
dive that is impossible to replicate with any other piece of diving
equipment. Whether a diver wants to easily descend to a deep
wreck and then effortlessly circumnavigate that wreckage in only
a few minutes or gracefully glide through miles of underwater
caverns, a scooter can make the difference between a great dive
and an arduous one.
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