Diver Propulsion Vehicles, or DPV’s among friends, have been around for years. They first started out with military and commercial divers, needing to cover large areas quickly, but they have since moved into the realm of recreational divers.
The fun facts
Mostly used by technical divers, these handheld submarines use an electrical engine to drive a propeller which generates thrust. The diver holds on with two handles, which also serves as the accelerator and steering mechanism.
Speed is typically around a couple of knots, though bigger, more powerful scooters can move faster.
Tech divers love them, because they make long dives more comfortable and help conserve gas, and make it easier to fight against any currents. Also, for very deep dives, they make dragging a number of stage bottles less awkward.
Non-tech divers also have a fascination with the small, compact units, though. Not least due to the James Bond-effect. It’s next to impossible to not feel a little like Sean Connery in Thunderball when being dragged along behind a DPV, the whirring of the propeller in your ears.
But from a more practical perspective, they’re pretty useful as well. Dives that features a risk of strong currents is made much safer (or possible). Large reefs or wrecks are suddenly circumnavigable on a single dive, and the lack of physical strain means dives are often extended quite a bit due to lower air consumption.
The must know of DPV’s
There are several types of DPV’s, from large sled-like types that can be used by two divers at a time, and carry quite a lot of cargo. To simple, compact types, where the diver holds on the unit and is towed by it, called tow-behinds.
The former are mostly used by commercial or military divers, and later by recreational divers.
There are a few things to consider before venturing on your first DPV dive, though.
- You’re moving faster, not just horizontally, but vertically in the water column, too. This means that you potentially shift depths much, much quicker than if moving under your own force. So that old dive course advice about monitoring your depth? Goes double when you’re diving with a DPV.
And be particularly careful about ascending, as ascending with a speed to 2 knots/hour is way above the recommended ascent speed.
- Keep your underwater navigation in mind. You’re moving faster, which means you can get lost faster. So be very mindful of where you are and which way is back to your exit point.
Of course, this is particularly important if you’re using a DPV to dive in a cave or wreck (which should only be done by very experienced divers).
- Speaking of bearings, remember that the UPV is mostly metal. That means that it can mess up your compass. So when you do take your bearings, make sure you hold your compass away from the DPV, or risk getting a false reading.
- DPV’s have a limited power supply, and when it runs out, they stop working. Power supply is stated in time, and standard DPV’s often have a use time of a couple of hours. Larger battery capacity can mean longer operating time. But this is in a best-case scenario.
Speed, current, water temperature, and the age of frequency of use (in particular charge cycles) can all affect the longevity of a fully charged battery. So be conservative when estimating how much power you need to complete a given dive.
- Tether yourself to the scooter, in particular if it is the tow-behind type. This means you avoid the risk of losing grip on the scooter in the middle of a dive and having it disappear from sight.
Most scooters have pre-fixed attachment points for this. Use the D-rings on your BCD to clip onto. If you use a wing-and-backplate setup, the D-ring on the front side of your crotch strap is intended to have a scooter clipped onto it.
- The whirring of the propeller, and possibly the electric field of the engine, does seem to scare off certain marine wildlife, in particular sharks. This isn’t 100 percent proven, but a lot of dive operators have noted a correlation between lack of shark sightings, even at sites where they are very frequent, and the use of DPV’s.
Also, it is quite probable, as sharks have a highly developed sensory apparatus, including the ability to pick up on electric fields. So if the purpose of your dive is to see sharks, consider leaving the underwater scooter on the shore.
So what are keeping you away?
The main thing that keeps most divers from using DPV’s is probably cost. A good DPV will set you back quite a bit.
But if you’re curious about trying it, a lot of dive centers have courses in using a uw scooter, typically as specialty courses, which can be a quick, inexpensive way to try it, and learn the basics or using it.
After that, more and more dive centers actually offer DPV rentals, which allow you to cater to your inner Navy SEAL without breaking the bank.