DPD Pegasus Thruster Leisure

I suspected that the novelty of zipping around a wreck effortlessly would soon wear off when balanced against the organisation and maintenance needed for an extra bit of kit. But there are plenty of circumstances where the extra power would be very helpful – in places where the currents are strong, for example.
I told Dean Vittali, the Thruster’s inventor and manufacturer, that I was off to dive in the ripping currents of the Dampier Strait in eastern Indonesia. I relished the idea of getting the extra oomph of a Thruster on my back to help me negotiate the flow of water on the reefs, and place myself better to take photographs.
Dean kindly lent me a Leisure version to take with me.

The Leisure Unit
The Thruster fits onto the diver’s tank by means of a specially designed mount, and is held tight by a conventional camband. The way in which the unit snaps into place on the mount betrays Dean’s background in aircraft-engineering. The whole thing is beautifully constructed.
With its battery fitted, it looks a bit like a small missile with a propeller set within a cowling at the rear end. The mount has to be positioned so that the cowl and propeller sit proud beyond the end of the tank when mounted.
A control cable is fitted via a wet-connector at its front end, and this has a large on/off switch button positioned at the business end of the control cable.
The main difference between the Leisure version and the commercial version, besides its blue anodising, is that it comes with one battery-pack instead of two, and a rather slower charging unit.
With a total run-time of about 45 minutes and a full charging time from flat of about six hours, I thought I was going to have to be selective about the dives on which I used the device.

Transport
The unit consists of the drive, the battery-pack, the frame that connects the two securely together, the tank mount with its camband, the control cable, and the charger.
I packed it, broken down into its constituent parts, into a hard case, and wrapped it for safety in my wetsuit. It weighed less than 12kg at the airport check-in.
It was a pity that Emirates lost the bag between London and Jakarta, and I had to wait six days before it arrived at my location on Kri Island. This meant that I got to use it for only one day at the place where I really needed it. But I used it further on a liveaboard trip in southern Raja Ampat, where the currents are less demanding.

Charging
The battery-pack slides off the power unit, and both items slide with precision onto the mounting-frame, to be located by large spring-loaded pins and linked by a wet-connector. This allows you to change battery-packs under water, as with the commercial unit.
To charge the unit, a large plug is removed from the battery-pack.
This is made watertight by a heavy duty O-ring. It is only at this point that a badly maintained unit might be vulnerable to a flood.
You then connect the intelligent charger, being careful to insert the multi-pin plug in the correct orientation.
A red light on the charger denotes that the big ni-mh battery-pack is taking a charge, and a green light that the charge is complete.

Considerations in Use
I needed to place a bit of non-slip material between the metal of the tank-mount and the tank to position the Thruster absolutely securely.
I also noted that although the assembled Thruster snaps instantly into place on its mount, helpful dive-boat crews had some difficulty doing this (I don’t know why).
I ended up fitting it to the tank myself, and wearing it for the short inflatable-dinghy rides from either the jetty or the mothership.
A safety-pin is inserted in the frame after mounting, and this came attached by a lanyard to the tank-mount.
This was also a mistake, because with the tank-mount staying on the tank, the latter is bound to be set down on the safety-pin at some time, bending and breaking it.
Learning the hard way, I salvaged what I could of the pin, and reattached it by lanyard to the Thruster mounting-frame instead.
It came to no further harm. I believe Dean has learned from my experience, too, and the safety pin’s regular lanyard fixing has since been moved from the tank-mount.
I was also wary of fingers getting caught in whirling propeller blades, so initially chose not to fit the wet-connector of the remote control until I was ready to dive.
This was also a mistake, because less-than-careful insertion in its female part while in a rocking boat by a less-than-observant boat-driver bent the male-part wet connector.
I had to straighten it later.
Instead, I resorted to assembling the whole thing and wearing it before diving, staying aware of its extra dimension added to my tank, and the fact that it made an overhang.
On surfacing, I disconnected the remote-control myself and dismounted the Thruster from the tank-mount before passing it up into the dinghy, followed by my tank and other diving equipment. The frame on which the assembled battery-pack and drive unit are mounted has a grip to make handling easy.
I also noted that, because the mount stayed all week on my tank, along with my BC, it suffered from not being rinsed in fresh water after every dive. I soon noted a little electrolysis starting between the stainless-steel fittings and the aluminium body of the mount, and cured the problem with a squirt of WD40.

In The Water
My first experience of the Thruster Leisure was in the ripping currents of Cape Kri. While others hooked in to watch the show, I was able to buzz over to where I wanted to be.
It also gave me the confidence to swim down to a mountain of sweetlips on the sand at 40m, knowing that I would easily be able to get back to the reef. To steer, I simply pointed my body in the direction in which I wanted to go.
The Thruster weighs around 2kg negatively buoyant in the water. Using it with an aluminium tank and very little extra lead (only 2kg), and because I was wearing the latest in neutral-buoyancy diving suits, the DPD’s weight was a little top-heavy on the tank. This took a little getting used to.
There is a slight delay between pushing the button and the drive operating, thanks to some electronic diagnostics. Then it goes, and, unlike many DPVs, it goes almost silently! There is only the distant hum of the sort of motor that might power a big electric drill at low speed.
If testing the unit out of the water before diving but wearing it, you need to get someone else to tell you if the propeller is spinning.
Because all the weight of my diving gear was in the Thruster, it tended to lift the tank a little, and I felt the push applied at my shoulders.
A crotch-strap would have solved this initial problem. It doesn’t happen when used with a steel tank or with a heavier suit and more lead on the weightbelt, and I soon got used to it.
My only regret was that I hadn’t had the benefit of the Thruster during dives around the Dampier Strait earlier in the week, when I had needed to hook in against the flow, and was not always where I wanted to be.
Using the device only when I needed to challenge the prevailing current, I guess it was running for a total of 15 minutes per dive, so the 45-minute run-time was good enough for a day’s diving.
Once we had left Kri and joined our liveaboard Mandarin Siren, I lent the unit to Deidre, the Irish dive-guide and boat manager, for a session. She buzzed about throughout the dive around Boo Rocks in the south of Raja Ampat, and obviously enjoyed the experience.
The great thing about the Thruster is that it is unobtrusive during the dive until you need it, and leaves your hands free to use a camera.
I threaded the business end of the remote-control through my BC waistband so that it readily fell to hand, and can say that while propelling forwards under power I became very aware of the poor aquadynamics of my big camera rig, which became quite heavy after a time. Consider the engineering, then look at the price!

COMPARABLE PRODUCTS TO CONSIDER:
No hands-free products in use

SPECS
PRICE £1300
DEPTH-RATING Each unit is individually tested and certified to 77m
MOTOR 12V with safety clutch
BATTERY Ni-mh with low-voltage disconnect electronics
CHARGING TIME 6hr
RUN TIME 45 minutes plus
CONTACT www.pegasusthruster.com
DIVER GUIDE