Diver propulsion vehicles (DPVs) help scuba divers move faster and go farther. With their high fiddle factor, they keep the batteries charged and the unit well-assembled. However, divers will have to be extra careful when driving a DPV.
Diver Propulsion Vehicles (DPVs) are the ultimate go fast personal underwater flight machines. Driving a DPV feels like a cross between being an aerial stunt pilot and a dolphin. “Awesome” collides with “reality” when you carry the none too dainty machines to the water’s edge or boat, deal with batteries and try to plan a traditional dive profile. The effort is worth it – read on.
Your DPV adventure starts in a professional dive store. Plan on spending $1,500 or more per scooter setup, including the propulsion unit, battery and charger. Optional accessories include carrying cases, depth/compass/meter mounting panel or an orally inflated flotation jacket. Boat divers often purchase a spare battery so one can be charging while another is in use.
Using a scooter without kicking reduces your air consumption by about 50 percent. You can go farther and faster than you ever imagined. The euphoria of doing loops, barrel rolls or drag strip dashes is fun. And, it makes a traditional “go to 60 feet, follow the reef to the end, turn around, swim back and ascend the anchorline” plan a myth.
This is where you have to get serious about dive planning. Set a maximum depth and stick to it. Use a dive computer to track your multi-level profile. Consciously remind yourself to exhale every time you point the DPV upward. There’s something about the excitement of a fast DPV ride that makes you hold your breath – just as you would when riding a roller coaster or when driving a motorcycle or car very fast.
It is easy to ascend or descend too fast with a DPV. (Most divers ascend too fast without one.) Your tiniest bubbles ascend at about 60 feet (18 meters) per minute. Consider holding onto the scooter and kick for ascents and descents. Resist the temptation, for your health’s sake, to make a rocket-diver blast to the surface. While you are ascending and descending slowly, remember to continuously clear your ears. It is easy to forget to equalize and hurt your eardrums. So, begin swallowing, popping your ears or wiggling your jaw – whatever you do to equalize – and keep doing it constantly as you change depths. When planning the distance you intend to cover with the aid of a DPV, stick to the one-third rule. Use one-third of your air going, one-third returning and save one-third for a safety reserve. If the scooter should quit running at the farthest point of your dive, would you have the air and physical stamina to drag the unit back to the boat or shore?
Commitment to buddy DPV diving means more than same ocean, same day. It is more fun to share your underwater experience with a buddy. Both divers need to have their own DPVs – there’s no recommended way to hitch a ride. A plan is doubly important when DPV diving or one diver spends his/her time chasing down the wandering buddy – no fun.
Beach/Boat/Kelp Diving Techniques
Assemble the scooter and battery in a dry, non-sandy place. Evaluate the conditions carefully before deciding to use the scooter on a dive. If you wouldn’t take a camera through the surf, don’t try to take a DPV.
For an Apollo or Farallon type DPV, hold the scooter by the handle when making a beach entry. Do not use the motor one-handed or when the unit is only partially submerged. Wait until you are at least waist deep to grasp the handles with both hands and then take off with the unit completely underwater. With a backmounted Parkway Nautilus type system, the key is not to roll onto your back in very shallow water and risk hitting rocks or getting entangled in seaweed. When exiting from a beach dive it takes practice not to use a handheld scooter like a bumper or extension of your arms. Protect the unit from crashes. Once on the beach, lie a DPV on its side to keep sand out of the shroud and propeller areas.
Boat diving handling techniques begin with placing the unit so it won’t roll or fall over. Work with the boat crew to stow the DPV in a tank rack, in its own case or another area where it will be stable. If using a backmounted DPV, double check the bands that hold your BC to your tank. The bands must be tight to secure the propulsion unit. Envision the scene when loose bands let the tank and/or DPV slip out and the regulator is ripped out of your mouth or the DPV disappears over a wall.
Before you jump in the water, connect handheld units to a sturdy rope or mountain climbing-style nylon line with a large clip. Then, gently lower them over the side. If it is not possible to do this, have someone hand your DPV down once you are positively buoyant in the water. A word of caution: Few people can bend over from a boat deck to hand you something. They get close and then drop the item. A camera is one thing – a 40 pound DPV is good for a broken mask and nose. Never allow the scooter to be handed to a diver on the surface by the handles. Accidental starting of the motor when handled in this manner could cause injury to the diver and damage to the scooter.
Backmounted DPVs need to be slid onto the mounting bracket affixed to the tank, the batteries connected from a waistbelt to the unit and the control wire run to the diver’s wrist and hand. Once outfitted, the diver is wider than usual and needs to be careful not to destroy a boat’s woodwork or clobber other divers. A gentle entry into the water by sliding off a swimstep is easier on the diver and DPV than a giant stride. Exiting, the unit may throw the diver off balance when coming up a narrow ladder. If this happens, inflate your BC, take off the BC/tank/DPV and hook it onto a line. With assistance it can be pulled up once you have removed other gear.
Kelp diving is a challenge. The standard propeller shroud and an optional propeller screen help prevent seaweed or kelp from becoming entangled – most of the time. DPV manuals suggests you not operate the machines where things could be sucked into the propeller. Experience and common sense are powerful tools but, if in doubt, turn off the DPV and swim to a clear area.
If you position your body behind the DPV’s propeller, you will get cold faster from the windchill-like effect of the prop wash. Also, your arms can get tired easily and it is hard to see directly in front. Backmounted DPVs avoid these problems by putting the prop wash above the diver, freeing both hands and not obstructing sight lines.
The Apollo handheld DPV suggests divers assume a position just above the unit. Hold the handles with straight or bent arms, whatever is more comfortable. If using the bent arm position, keep the scooter parallel to and below your body. Rest your abdomen on the upper part of the shroud. The more level, or parallel to the prop wash the diver can maintain his/her legs, the less turbulence is created and more speed and distance are possible.
Dangling gauges or straps are no-nos with a handheld DPV. Murphy’s Law is a diving companion – if you have a flapping strap end on a BC or weightbelt, it will be caught in the prop at the worst possible time. Streamlining your profile by removing dangling slates, bulging pockets or anything hanging from a clip on a weightbelt will reduce the amount of drag and increase your speed and/or distance potential.
Protect the unit from saltwater corrosion by washing it after every use with freshwater – pay particular attention to the prop, switches and buckles. Put the unit in a shady place to dry. Take the battery out, if applicable, and charge it fully within 24 hours of use.
Check for water seepage in the areas of your scooter that have a tendency to leak. For example, on the Apollo scooter a small amount can leak into the outer clutch housing. The Apollo owner’s manual suggests you check the clutch housing. Detach the outer housing, rinse with fresh water, dry and reassemble the O-rings and housing cover. All the usual warnings about O-rings, grains of sand and lubricating that apply to cameras, apply to DPVs.
Scooter bodies are easy to clean with freshwater and a mild detergent, such as dish soap. Avoid chemicals, oil, petroleum greases (including Vaseline) alcohols, acetone and strong detergents. Use pure silicone grease to lubricate O-rings, rubber and plastic parts.
Batteries are the lifeblood of the DPV. They are expensive and demand careful treatment. To obtain maximum performance from a battery:
* Do not place batteries near heat, such as direct sunlight, heaters, radiators, engine rooms, hot car trunks or furnace rooms.
* Charge batteries within 24 hours of use. Do not let a battery sit around dead.
* Do not totally discharge the battery. When you hear the unit slowing down, stop using it. It is OK to come close but avoid a complete discharge.
* Charge the battery fully. Undercharging reduces battery life.
* Use the battery charger recommended for or sold with your DPV. The manufacturer has selected a charger that is best suited for the particular brand and battery provided.
* Protect your DPV from rain, saltwater or salt atmosphere.
* Do not smoke or use open flames near batteries.
* Do not use chargers in an unventilated, closed room.
* Read the manual provided by the manufacturer for particular details about your battery. These may include suggested water or air temperature ranges for DPV use and storage, number of charges allowed on your battery or other cautions about installing or charging.
DPVs are great fun. Whether fooling around doing loops or using the scooter to cover great distances, you will add a new dimension to your diving. DPVs are not inexpensive, especially when a buddy pair needs two. They have a high fiddle factor to keep the batteries charged, the unit assembled and running. Propulsion units and batteries weigh about 40 pounds but, next to a scuba tank, it is the best 40 pounds of excitement you’ll ever own and well worth the effort and investment.