they just expensive toys, or are there some good reasons for using
diver propulsion vehicles? Matt Crowther looks at the superbikes
of the ocean
Let's be honest,
most of us like playing with fancy kit, and taking a scooter for
a spin is about as good as it gets! This is your chance to become
vehicles (DPVs) have been used by military and commercial divers
for years. Although their advantages have long been recognised by
technical divers, they are only just starting to catch the interest
of recreational divers.
Most DPVs, or
'scooters', come in two styles. 'Tow behinds', as the name suggests,
are designed so the diver holds on to a bar or handle, and is towed
behind the vehicle. They're fine for shorter dives but can become
painful to use after a while - the drag created by the bulk of your
BCD and other equipment puts a strain on your arms. Some units have
a bridle, so you can clip the scooter to your BCD. The other main
style of DPV is designed so the diver sits astride it. These units
are usually larger and more expensive, but they're more comfortable
to use over long dives and often have a longer running time. Other
styles include a small unit that clips to your diving cylinder,
offering hands-free propulsion.
DPVs are battery-powered,
usually by between two and four 12-volt rechargeable packs. The
life of the battery is measured as range (distance) or burn time
(battery life). A good charge will run some DPVs for anything up
to five miles (not all manufacturers supply a charger with their
unit, so it's worth finding out before you spend any money). The
batteries power a motor, which in turn powers the propeller. All
this sits inside a rigid plastic or aluminium casing, and that's
pretty much it. Some DPVs also have variable speeds, so you don't
have to travel full-out - unless you want to! An average maximum
speed is about 3mph, which sounds slow but underwater 3mph does
feel pretty fast.
If you're going
to hang out with other DPV users you'll need to know some of the
language. When you use a scooter you are a 'pilot' and you 'fly'
your machine. Some sad people even give their machines names - about
as stylish as giving your car a name!
|INSIDE A SCOOTER
you're using a DPV doesn't mean your diving is allowed ro
be any less streamlined. Reduce drag by configuring your equipment
close to your body and adopt a good flying position - it will
increase your speed, the distances you can cover and the battery
life. Loose and dangling equipment should always be avoided.
When flying a DPV you risk damaging yourself, your equipment
and your vehicle - remember you've got a propeller on these
things! Correct weighting is important - if you have to put
lots of air in your BCD you'll increase the drag factor dramatically.
Never rely on your DPV to stop you sinking like a stone. Equally,
don't load half your weight belt on to your unit. Finally,
carry a lift-bag. If you flood your DPV or want to leave it
for any reason this will allow you to do so and recover it
Diving with a DPV requires minimal effort. This is totally relaxing
diving. Some might say that it's lazy diving, but there are real
Your air supply
will last considerably longer - as much as 50 per cent.
There's less chance
of nitrogen narcosis and of suffering from decompression sickness.
If you're making
effortless dives you can concentrate on breathing patterns. Breathing
slowly and deeply helps flush out carbon dioxide - carbon dioxide
poisoning (hypercapnia - an increased partial pressure of carbon
dioxide in the bloodstream) is a threat often overlooked by divers.
For shore diving
you can use a DPV to make more interesting dives and travel further
out than would otherwise be possible.
If you've ever
been caught in a strong current perhaps you'll understand the difference
a DPV would have made.
It's important to be properly trained before using one
for the first time - speak to your local dive centre or branch.
A course should set you up with the basic skills, but failure to
stick to certain rules can create unnecessary problems.
DPVs are an additional
area of equipment that must be correctly prepared before every dive.
Read the manufacturer's instructions and follow a few simple steps.
It's easy to forget
yourself and just fly, ignoring maximum depth restrictions and possibly
increasing decompression stop times. Remember that if you do fly
up and down your buoyancy will change. Expanding air in your BCD
as you ascend might even force you into an uncontrolled ascent unless
you dump it.
lung expansion injuries are also a strong possibility.
Just because you're
on a DPV, don't dive 'saw-tooth' profiles. Descend to the deepest
depth first and work your way back up.
Consider the battery
life of any unit you use. Perhaps applying the rule of thirds to
your battery would avoid your machine 'running out of gas'.
If you make penetration
dives with scooters remember that if the machine does lose power
or totally cut out, you must have enough breathing gas to swim back.
Think about your
buddy. If they have a scooter, is it the same? If not, it may be
slower or have a shorter battery life. It may be possible for two
divers to use one DPV.
|Choosing your DPV
made up your mind to take the plunge and go for one of these
machines you will want to know how to pick the right one.
As you'll know from choosing other items of dive kit, every
manufacturer claims to make the best. There are good points
to most items of kit available for today's recreational and
technical divers. DPVs are no exception, so to get it right
you should consider what is most important to you. l If you
want to make long leisurely dives, comfort and battery life
are most important. Perhaps a seated DPV would be best. l
If you want to use the vehicle to travel short distances and
perhaps don't intend to use it for the whole dive, speed should
be the greatest determining factor in your choice. l If you
plan to penetrate wrecks or caves, choose a small system.
You should also look at small, lightweight units if you plan
to travel. Probably a tow-behind would be the best choice.
l Whatever you choose, it's worth considering a unit that
allows easy control of speed from the flying/riding position
and shows the amount of battery power remaining. Of course,
the best way to decide which DPV is right for you is to take
some for a test drive!
|WHAT'S ON OFFER
Top speed 6.3mph
Number of speeds variable
Maximum depth 65m
Range/burn time 2 hours
Dimensions height 46cm, length 208cm, width127cm
Total weight 122kg
Price From £6,120
||Dream machine for lottery
winners. The unit has been designed to carry on-board
scuba, and has a comprehensive instrument panel. An adjustable
buoyancy system is fitted as standard. Optional features include
a road trailer and camera mount.
Contact T-N-T Leasing in Florida on tel: + 1 954 764 1110.
|Scubapro Sea Glider
Top speed 2.2mph
Number of speeds 1
Maximum depth 70m
Range/burn time 50mins
Dimensions height 51cm, length 57cm, width 45cm
Total weight 21.2kg
|A marine stealth plane.
A patented design feature places the propeller below the main
body, allowing it to be used on the surface as well as underwater.
It has an instrument panel and optional light fittings. Scubapro
also offer a rigid carry-case with wheels for the scooter,
Contact Scubapro on 01256 812636.
Top speed 2.7mph
Number of speeds 9
Maximum depth 54.9m
Range/burn time 120 mins
Dimensions height 37cm, length 65cm, width 44.5cm
Total weight 24.5kg
||A high scorer in test
reviews. The Mako has a variety of of speed settings.
You can synchronise speed with other scooters. You can set
it to achieve the best speed and range for every dive. Power
triggers on both grips mean you can alternate if one hand
gets tired. Contact Oceanic on tel: 01404 891819.
Company 2000-20 and 2000-25
Top speed 2.5mph
Number of speeds 1
Maximum depth 52m
Range/burn time 55mins
Dimensions length 79cm
Total Weight 21kg
|Good value for money.
The Torpedo is operated in a unique way - a switch inside
the hand grip is triggered by a magnet that straps to your
hand. This ensures the unit will cut out should you loose
contact with it. It also means you have to release one hand
Contact Torpedo in Florida on tel:
+ 1 800 489 6774.
|Breathing Observation Bubble (BOB)
Top speed 2.8mph
Number of speeds 2
Maximum depth 12.2m
Range/burn time 1 hour+
Dimensions height 135cm, length 79cm, width 71cm
Total weight 43.5kg
Price £9,500 +VAT
||What can we say, it's
different, it's expensive! It has a combined steering
wheel and instrument panel that includes a decompression computer.
The glass bubble is continuously fed with air from the tank.
However, the user has to compensate for changes in pressure.
Light fittings are included, making night dives easier. Spymaster
also makes a small tow-behind. Contact Spymaster on 0171 486
|Aquazepp LST 14-24
Top speed 3.7mph
Number of speeds 4
Maximum depth 90m
Range/burn time 4 hours
Dimensions length 125cm
Total weight 35kg
Prices from £1,100
|Built with German precision,
popular with tekkies. Aquazepp makes 13 models, including
a twin version. Letters and numbers are used to denote certain
specifications, making it easy to pick the features you most
need. This model has a light, super motor, dry battery.
Contact Aquazepp in Germany on
tel:+ 49 8978582487.
Top speed 2.75 mph
Number of speeds 1
Maximum depth 122m
Range/burn time 3,200m
Total weight 36kg
Prices from £1,559
||The choice of US special
forces. The MK7 is available in two other versions. The
MK7-E comes with a variable speed control. The MK7-ER is fitted
with optional silver zinc batteries, extending the range of
the DPV by up to three times.
Contact Farallon USA on tel:+ 1 770 414 0550.
Top Speed 2.3+mph
Number of speeds variable
Maximum depth 100+m
Range/burn time 50-150 minutes
Dimensions height 25cm, length 79cm
Total weight 100kg
|A firm favourite among
some of the world's best cave divers! The Gavin has been
designed to take up to eight 12 volt batteries. This unit
has two. It's simple, just what you want at 100m. Probably
the best tow-behind for technical diving.
Contact e-mail email@example.com
Top speed 3.25mph
Number of speeds 2
Maximum depth 99m
Range/burn time 55mins
Dimensions height 56cm, length 51cm, width 47cm
Total weight 23.6kg
||Great depth-rating for a recreational unit. A tough
outer housing that should withstand most heavy knocks. It
is one of the few units that has a speed control located next
to the power trigger, making it easy to change speeds without
Contact Mode Industries in Florida on tel: + 1 800 226 0767.
Top speed 2.4 mph
Number of speeds 3
Maximum depth 50m
Range/burn time 1 hour
Dimensions 34 by 61cm
Total weight 18kg
|Tried and tested for
more than 15 years. Probably one of the best known recreational
scooters. Features include a power switch located on the
hand grip for easy operation and an optional wrap-around buoyancy
Phone Forward Diving on 01202 677128.