Lamp GreenForce F2 TriStar
There was a time when a torch was simply a battery, a bulb and a switch. Underwater torches were slightly more complicated because they had to be made watertight. People would make their own from a short length of drainpipe, a sealed-beam car headlamp and a wet-acid battery, all kept cosy with a big O-ring.
  Things have changed. Now you have a choice of power sources - ordinary alkaline dry cells, a rechargeable ni-cad battery pack or a hi-tech ni-mh battery pack.
  When it comes to the part that produces the light, alongside ordinary tungsten bulbs, higher-output tungsten-halogen bulbs and high-intensity gas discharge (HID) lamps, there are now also high-output light-emitting diodes or LEDs.
  No longer do you have a simple choice between a small, low-output torch or a larger, higher-output lantern. Many divers opt for a battery-pack fixed to their tank or another part of their kit, to be included in their lead ballast calculations. The business end of the light is fed by an umbilical cable.
  Of course, some hi-tech offerings are fearsomely expensive. GreenForce products are made in Belgium and aim to supply the effect at the minimum price, even if this means cutting down on sophistication. They are based on a sympathetic system of interchangeable parts. Buy the elements you need and select the solution to suit your needs.
  A burntime of 40 hours from a battery that charges in three to four hours, and a light output equivalent to 30W - thats the impressive claimed of the manufacturer for its F2 TriStar. How does it do it By combining a big battery-pack with high-output LEDs.
  GreenForce products have all the aesthetics of a 1950s Ascot water heater (though the unattractive ribbing of the battery-pack does provide a very secure grip with the thickest gloves).
  Neither are they exactly sophisticated. While other lamps have electronics to take care of the problem, with the GreenForce battery-pack gases produced by uncontrolled charging are allowed to escape through a simple pressure-relief valve. You have to unscrew the cable or lamphead screwed into the battery-pack and replace it with a plug provided.
  This has a rather primitive electrical connection into which you can plug the charger unit. At least the unit can be quickly modified to fit British, European or US plug sockets.
  The modular design allows you to screw together different parts of the product. You can screw a lamphead directly into a battery-pack and get a simple one-piece lantern or insert an umbilical cable with male and female connectors in-line to get a technical diving light.
  Its simple to remove the lantern handle from the battery-pack because it is held on with a single hexagonal-headed bolt. The secret of the F2 TriStar is the LED lamp head used instead of any of the other options.
  One LED would not produce enough light, so the designers have installed a group of three. The problem is that the reflector design makes it impossible to get all three LEDs at the point-of-focus of the parabolic reflector, so they have given each LED its own.
  The modular design uses a lot of O-rings - three in-line at each connection. The user needs to be sensible about maintaining these in a properly greased and grit-free condition.
  It doesnt help that you have to switch the unit on and off by screwing and unscrewing one of these connectors until contact is made or broken.
  I watched in horror once during a dive as someone to whom I had lent another GreenForce lamp unscrewed its lamphead far more than was necessary to switch it off, and risked a serious flood. But, given a cautious diver, the manufacturer is confident enough to give it a depth-rating of 250m. Thats surely enough for anyone.
  Although the TriStar offered such a long burntime, the light it produced was not particularly bright or penetrative. I dont know if this is a function of refraction under water but it looked cold and didnt seem to go very far as a beam, although I was seen by others from a long way off.
  I confess that I used it in the rather impressive company of a very expensive Swiss HID lamp that was nearly 32 times brighter. The comparison was unfortunate, because I am sure that had the GreenForce F2 TriStar been my only light source, my eyes would have become more easily adjusted to the gloom.
  The use of this sort of light does tend to do away with charging problems, but because the burntime is so long one would need to keep a log of its use or risk being let down at some point.
  My thanks to Nigel Wade for helping me with the underwater photography of this product.
The GreenForce F2 TriStar costs £315 in hand-lantern form and £360 with umbilical connections. It was supplied for this test with an optional 130kg breaking-strain coiled lanyard which includes a heavy-duty buckle and naval bronze swivel ends (around £21 extra).
  • Lumb Bros 0161 681 5790

  • Divernet Divernet
    + Less expensive than superficially similar options
    + Massively long burntimes

    - Slightly over-simplified, verging on crude
    - Not very bright