What is an Underwater Propulsion Vehicle
An underwater propulsion vehicle, also known as underwater scooter or diver propulsion vehicle (DPV), is a diving equipment unit used by scuba and rebreather divers to increase their so-called range underwater.
Range is described under three conditions, and these are the limited amount of breathing gas that can be carried, the rate at which the breathing gas is used under efforts while diving, and the limited time imposed by dive tables to prevent decompression sickness among divers.
A DPV has some basic components which are a pressure-resistant watertight casing containing an electric motor that is battery-powered, and this drives a component which is the propeller. When the design was made for this vehicle, it was in such a way that the vehicle should not harm the diver, diving equipment, or marine life, and that it cannot be accidentally started nor will run away from the diver, and that the vehicle has to remain neutrally buoyant while it is used underwater.
DPVs are typically used in cave diving and technical diving where the vehicles serve as a help in moving bulky equipment and thus allowing the diver to make better use of the limited underwater time as stated by the decompression requirements for deep diving. To make a DPV more useful, some accessories can also be mounted to the DPV accessory board. Compasses, cameras, lobster sticks, and also spear guns are some of the accessories that can be mounted on to the DPV.
DPV also serves for military applications that include delivery of combat divers and their equipment over distances or at speeds that can be considered as not practicable.
The operation of DPV requires more than situational awareness than mere simple swimming since its operation requires simultaneous depth control, buoyancy adjustment, monitoring of breathing gas and navigation.
There are several types of DPV, and the most common type is that which tows the diver while holding onto the handles on the stern or bow. This so called tow-behind scooters are most efficient with the diver placed parallel to and above the propeller wash.
Another type of DPV is called manned torpedoes which are fish-shaped vehicles where one or more divers can sit astride or in hollows inside.
The next kind of DPV is called a subskimmer which is described as a rigid-hulled inflatable boat, powered by a petrol engine when on the surface, and when being submerged, the petrol engine is sealed and the vehicle runs on battery-electric thrusters being attached on a steerable cross arm.
By now, you would have realized that as DPVs get larger, they gradually become submarines. There are also small submarines called wet subs, where the pilot’s seat is flooded that then requires the diver to wear diving gear.
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