DPV SEA BOB JET 4.12

IT SEEMS TO BE PART of the human condition that we like to equip ourselves with things that far surpass our needs. Witness the Ferraris, the Porsches, the Aston Martins and the Maseratis slowly negotiating the speed-humps in London suburbs.
It was no surprise that the £90,000 DPV exhibited by the German manufacturer SeaBob at the international DEMA show drew crowds of drooling divers.
How many stopped to think that an underwater vehicle with a top speed of 22 knots was rather less than useful for a scuba diver? We all want to be James Bond, don’t we?
That said, I was quite excited at the prospect of trying a more modestly equipped SeaBob, though it was the almost-entry-level SeaBob Jet 4.12 that was delivered to Wraysbury Dive Centre for me to try.
This model is second from bottom in a modest range with propulsion units in the order of 3, 4, 5 and 7hp, and with a surface top speed of a mere 7.5mph.
Of course, under water there’s a lot more drag, especially if the scooter is being used by a diver wearing a big tank and drysuit.
I was wearing a very sleek O’Three suit that fits me like a glove (thanks, Sean), and without any sea-anchors (thigh pockets) and with a Buddy back-flotation BC I hoped to be slick.
My fins may have slowed me down, but I wasn’t prepared for a long swim without them across the lake should anything untoward happen to the SeaBob.
I picked a regulator that was least likely to freeflow in the strong current generated by my forward motion. My buddy Nigel Wade used his side-exhaust Poseidon for the same reason.

Electronics
So how does this DPV differ from the ones that are so familiar? Traditional units have a big battery powering an electric motor that drives a propeller. The motor is controlled by a mechanical trigger grip.
The SeaBob varies only in that the battery-pack is a cluster of 12 lithium-ion cells giving 1.8kW/hr and 48V at 40Ah. Instead of a mechanical speed control, it has an electronic control that can be set during use via Piezo buttons for one of 10 power levels.
Operating time at full-power of the Jet 4.12 is about 75 minutes, and the full charging time with the quick charger unit can be as little as 90 minutes.

Safety
You don’t need to break into the SeaBob to charge it. It is factory-sealed for life, and has an external charging connection to avoid problems with flooding.
The manufacturer, aware that many of these toys will be bought by the super-rich and probably rarely touched, has provided a preset-depth safety device operated by an inbuilt pressure sensor.
This can be set for any depth up to 40m, but as a default, and with snorkellers in mind, it comes factory-set with a 2.5m depth limit.
Alas, we didn’t have the PIN-code needed to change this setting, and had to content ourselves with the sensory deprivation of hurtling round Wraysbury Lake at 2.5m deep or less, and without any actual visible datum to tell us where we were.
If we went any deeper, the motor simply cut out, and we floated slowly back to the surface.

Jet Power
There is no visible propeller. Water is sucked in through the SeaBob’s gills and forced out at the back with an impressive display from the jet out-take, especially when you hold the unit nose-down and fire it up with the jet out of the water.
This means that you can lie on it, grasping the handgrips, with no fear of getting anything sucked in and tangled in the propeller.
We found that we could steer simply by leaning one way or the other, rather as one does on a motorcycle.
In fact the SeaBob looks a bit like a sports motorbike without wheels, prompting one onlooker to ask where the petrol went in!
The electric motor powers an impeller set in a jet channel, and the thrust developed propels the SeaBob forward in an instantly responsive way. The hull is designed to be as aqua-dynamically efficient as possible, but I was not, so releasing the power button always brought me to an abrupt stop.

Engineering
Designed and made in Germany, the SeaBob’s electric drive unit is said to suffer no wear and tear, and has been tested to 10,000 hours of operation under full load with no breakdowns or reduction in output.
The battery-pack is claimed to be good for more than 2000 charging cycles.

Cockpit Controls
Four buttons, two of which are used in the water, do all the controlling. Apply light pressure with the thumb to the green button on top of the right-hand grip to apply power.
Repeated pressure on the red button on the left grip reduces power in 10% increments.
The other buttons are used for setting the predetermined depth-limit and programming the individual data menu. An illuminated LCD displays data such as the power-setting percentage, remaining battery charge, actual depth and water temperature.

In the Water
At first I opted to use the SeaBob in its floating mode, so that I could practise and hear any instructions that I might have needed to take on board. I didn’t need any; it was that simple.
We then loaded the unit with its diving ballast in the form of a bolt-on weight (£190 extra) and I took it diving, powering down from the surface. It was at this point that I discovered its 2.5m depth limit.
That wasn’t going to stop us having a lot of fun, and I got Nigel to attempt some dolphin leaps with it, which is a lot to ask of any DPV, especially hauling a drysuit-clad diver with a steel tank and lead weights.
I can’t confirm what speed we achieved, but it was the first DPV I have used that made the fabric of my close-fitting drysuit ripple at high speed as the water passed over it. I guess it was almost twice as fast as a typical caver’s DPV.
There was never any problem with jet-wash, because the water spewing out from the jet nozzle was still forming a small cone after it had passed my feet.
I simply leant one way or the other to steer. If only I had been able to see where I was!
Of course, this did stir up the bottom a little, but by the time you read this the visibility at Wraysbury should be back to normal.
There are three downsides to the SeaBob, as far as I could see. The first was that my arms started to get really tired hanging on to it, and the second is that at 63kg it’s very heavy to haul out of the water.
The other downside is the price of £9400. Prices for similar models with differing performances vary from £7900 to £13,600.
There is a full range of appropriately costly accessories, including a boat-lifting system that will avoid damage to your Riva Tropicana when you pull the SeaBob onboard.

OTHER SEABOB DPVS TO CONSIDER:
SeaBob Cayago, Magnum £90,000
SeaBob Cayago F7, £13,600
SeaBob Rave Jet, £7900

SPECS
PRICE £9400
BATTERY PACK 12 li-ion cells
OPERATING TIME 75min
CHARGING TIME From 90min
DEPTH LIMIT 40m
CONTACT www.rochemarine.co.uk
DIVER GUIDE