Since the pioneering era in the seventies, Guido Gay took the way of developing only battery operated underwater vehicles.
This choice was a direct consequence of the fact that umbilical cables are critical limiting factors to vehicle’s maneuverability: cable diameter ought to be kept to a minimum. Therefore, what was better than having a cable solely dedicated to communication? Eliminating the need of copper wires for sending power down to the vehicle from surface?
Yes, the challenge was tough.
Today nearly all the available vehicles are sticking to a common scheme:
all of them are constructed around a rectangular frame holding a number of pressure resistant containers each of them housing single functions, one for camera, another for electronics, other for motors, for sonar, for light, etc. all of them interconnected with wet cables. Then syntactic foam floaters are added and power is taken from the surface through the umbilical cable.
These cables have diameters ranging from 10 mm up to 30 mm or higher.
It is easy for everyone to imagine the difficulties associated to a vehicle moving underwater and having to pull a cable of such a size.
On average a conventional vehicle capable of 2000 m depth operations may have a mass of one ton, requiring a cable reel of two tons and 50 kW power generator. Nothing less than a ship is capable of supporting all that.
This compares to a mere 3.5 mm of PLUTO cable, to 60 kg vehicle and an additional 60 kg cable reel.
Propulsion considerations: a common solution to the “square” vehicles is called “vectoring” thrusters, where 4 propellers are placed in the horizontal plane to create fwd/rev, sideshift and yaw. Two of these thrusters are placed on the front of the vehicle and can therefore lift a mud cloud when pushing water forward in the vision area. Most severe disturbance affects the largest and more powerful vehicles.
Our PLUTO vehicles are using two parallel horizontal propellers placed in the rear for fwd/rev and yaw. Two vectoring vertical propellers for side shift and depth keeping are placed on top of vehicle and set to push water upwards most of the time. This arrangement assures no disturbance at all.
Our non-conventional design concept is generating the highest degree of integration and optimization. Unlike other manufacturers that are purchasing off the shelf underwater units and assembling them into the “square” frame, most of our vehicle’s components are sophisticated designs made in house in order to perform exactly as needed, no surplus, top performance and simplicity of use: we manufacture all the electronics, sonars, lights, thrusters, connectors, manipulators, etc.
Great attention is given to the vehicle’s shape in order to minimise drag, improve speed, efficiency and underwater mobility. Buoyancy is carefully calculated so that there is no need for floatation material which is origin of weight and cross section increase, as well as depth limitation. The PLUTO designers are not only technical engineers but they own the lifelong experience of a mariner and navigator.
The result is equipment ergonomically friendly to professional pilots and deckhands.
Though all the applications requiring round the clock endurance are not for us, our vehicles are ideal for deep missions of several hours or shorter missions in strong tidal currents and far away from the ship.
This modus operandi was exactly what Navies were looking to perform mine hunting activities. Our general purpose PLUTO vehicles were and are built in accordance to the strictest Military Standards. For 40 years until now we have been one of the major manufacturers in that area and probably today the best one.
Our battery operation concept is now extending endurance and getting new momentum from newly available powerful batteries, new brushless motors, new LED lights.