In the past when I have done dive trips such as Truk Lagoon and the President Coolidge I have taken a spare wrist computer attached to the D-ring on my BCD computer. The reason behind this was so if a computer failed I continue diving without missing any of the dives while waiting to degas for 24 hours so I could start diving again with a new computer. Oceanic have taken this concept and improved on it through the development of the BUD backup dive computer.
The BUD is an innovative backup device that clips onto your BC or placed in a pocket that constantly tracks your dive profile, just as your primary computer is doing. Using the same two algorithms that are set into your computer, whether you are diving on air or nitrox, NDL or Decompression diving, having this small guy diving along with you takes that worry away. Having only one button to adjust your settings, it is simple to use, read and even gives you visual alarms to finish your dive if it becomes necessary to use. As it is programmed to monitor 12 nitrogen compartments, the tissue loading bar graph will display the one controlling your dive, and there is also a variable ascent rate indicator, which flashes SLOW if your ascent is too fast. The in four different colors red, yellow, blue and orange, so keeping track of your own BUD is easy when diving in a group.
The BUD is activated by water, although that can also be done by pressing the button. This mean you just attach it on your BCD and forget about it throughout the dives. The only time you need to think about it is when something goes wrong, and at that time it is there to keep you diving safely. The BUD is now a necessary piece of equipment for every diver who takes diving seriously.