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MB Sub Twin LED Cave
Following on from the excellent Photon LED Cave MB Sub have taken a bold an innovative step in the field of torch options and redundancy. The present trend of torches demands a tight beam for signaling / underwater communication and a high lumen output. The needs of cave divers and multi dive divers is for ever longer burn times, preferably without the massive battery packs we required in the past.
Pre 2000 a 60min burn time on a 50W Halogen torch was considered ample light and ample burn time for open water diving. After all, you don’t need a torch on deco. However the cave divers were pushing through the dark all the way out and they required a margin of safety on top of the planned dive time. Four hour + burn times meant carrying massive battery packs and the open water divers displayed no desire to be lumbered with those unnecessarily. The advent of very small and very powerful NiMh and lately Lithium Iron battery’s changed all this. The want for monster burn times spilled over to the OW diver.
If there is such a thing as a “benchmark burn time” Id hazard the suggestion it would be considered today even by open water divers to be in the region of 4 hours.
At the same time as this demand for increased burn times occurred we started to demand incredible light power. 50W Halogens were no longer considered powerful enough as 18w HID’s became the must have piece of kit.
Again if there were to be a benchmark power out put today’s id suggest it is the 21W HID. There are more powerful lights and there’s plenty of diving that doesn’t require 21W HID performance but this does appear to be the generally accepted standard among the technical diving community.
Now a well established market, the HIDs have suffered from issues with faulty ballasts and fragile bulbs. The loss of a primary light being of great concern to all divers, the market has opened up for the emerging technology of rugged, solid state, high performance LED torches. These satisfied the demands of those who have lost faith in HID bulbs and in some cases for those divers who find the intensity of a HID light to be less than optimal for their stile of diving.
If your designing a torch for the diving community today you need to do something quite special to stand out from the crowd of 21W HID’s and multi emitter LED heads. You also have to remember the key issues:
1: Reliability
2: 4 hour Burn time minimum
3: 21W HID performance
4: A tight focused beam for signaling
5: Good general illumination.
Enter the MB SUB TWIN LED CAVE
The new TwinLED head fits on to the standardized Photon battery pack enabling owners of the Photon to upgrade by purchasing the torch head only. Milled from a solid billet of aluminum it is depth rated to 200m and contains a choice of 1000 lumen Ostar LEDs.
The heads can be configured with a 10degree spot bulb and 20degree flood, two spots and of course two floods. In operation the diver has the choice of a single spot on 50% power offering a staggering 12 hours burn time or a single spot on 100% power offering six hours burn time.
Spot Flood Head
Spot Spot Head
Should a bulb fail the second LED can be switched on with no loss of performance. Each bulb is individually managed to allow complete redundancy in all areas with the obvious exception of the connection to the power source.
For wreck divers and especially cave divers, having this redundancy in the torch head offers real security. Back up torches are able to get you out of a situation where a primary has failed but they are not designed to allow the dive to continue as normal. This twin LED system offers the diver the opportunity to carry what is basically a redundant primary torch covering the main failure areas of the bulb and the controlling electronics.
However, on the occasions when the diver should require optimum power from his torch they have the further option to switch on both light heads and produce 2000 lumens of light. In doing so the burn time will drop to just over two hours thirty five min’s on a full charge, which should still be more than adequate for most dives.
In order to avoid total loss of illumination and damage to the batteries by fully draining them the MB Sub has incorporated some clever discharge protection controls. At a pre set power out put level the torch will revert to power save mode giving over an hour and a half of further emergency use.
With the range of options available the diver can decide to run the torch in safety mode of a single bulb running for maximum burn time with redundancy in the primary head. At time where more power is required he can simply double the light output by switching on the second bulb and reverting to safety mode again once the moment has passed.
DESIGN
The new head incorporates the excellent fully adjustable Goodman’s handle previously used on the Photon. Adjustment is via Allen bolts which fit a standard scuba tool ensuring you will be able to adjust them at most dive sites even if you left your tools at home. Id still prefer a simple screw for this which can be adjusted with the edge of a knife or a coin but if your going to use an Allan bolt, this is the next best choice.
A well thought out loop is designed in for attaching a P clip and the light head controls are lockable to ensure stowed lights are not accidentally turned on. The red knurled knob screws down into the dimples in order to achieve a definite lock on the chosen light option.
Position 1: Half power single bulb. Position 2: Full power single bulb and Position 3: Full power duel bulb. As before the head is attached via a double 0ring sealed connector and power is transferred through a gold plated coax type plug.
In use the light head feels very comfortable and controls are easy to operate. However you do need to take care not to over tighten the locking nut making it difficult to undo with gloved hands and limited grip. The switch is a magnetic proximity type offering no failure point for flooding.
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Originally Posted by RogerViking 
