Suunto is a Finnish company which has specialised in navigational instrumentation primarily for seafarers for 60 years. It's diving division is actually an original manufacturer (they don't just sell someone else's product under their own label) of depth and pressure gauges, compasses and computers. Suunto's first computer, the SME, was launched in 1987 and was notable for its small size and innovative logbook function, which allowed the user to recall dive profiles in three minute increments without accessories. Ten years on, Suunto offers a full line of computers that cater for divers wanting no- decompression or full-decompression facilities, to use air or nitrox, or requiring gas integration.

The Favor is designed for 'normal' air diving. Because it provides enough data to plan decompression stops (ie total ascent time) among its displays, we consider it to be a full decompression computer.

Our Red Sea Test Team test-dived the Favor extensively, making 71 dives and accumulating more than 61 hours bottom time.

The Algorithm

Suunto's algorithm, the 'table' that monitors the diver's nitrogen levels during, between and after dives, has as its basis the same research that created the US Navy Tables. However, important modifications have been implemented to take account of more recent research and make the computer more conservative. For example, 'silent bubbles' are thought to occur during and after ascents. These bubbles may not cause problems immediately, but they may remain in the diver's body for hours or days, and slow down the release of nitrogen. This is difficult for a table or computer to predict, and repeat dives only add to the problem by causing more silent bubbles. This increases the chance of decompression sickness.

Suunto's designers have worked hard to minimise the formation of silent bubbles in the first place. Suunto uses lower permissable saturation levels, less 'gassing off' on ascent, and shortened no-stop times in line with respected research carried out by Dr Merril Spencer. A 10m/33ft per minute ascent rate is also used to further inhibit bubble formation (18m/60ft for US Navy tables) and a safety stop is recommended.

The Suunto also uses longer 'half-times' than the US Navy tables. Half-times represent the time different body tissues take to absorb and release nitrogen. The Favor's longest half-time is 320 minutes, enabling it to consider dives made up to 32 hours apart. Longer half-times are expected to provide a greater degree of safety for people diving intensively, such as those making extended decompression dives, or long repetitive dives over many days typical of liveaboard divers. The original theory that most tables and computers are based on, assumed that the body absorbed and released nitrogen at exactly the same rate. This is now thought to be wrong and Suunto's algorithm has been modified.

Instructions

Before you even get to 'Activation' there are no fewer than 15 warnings posted in bold in the instruction booklet. Many of these are anti-litigation notices (Do not use for decompression, do not dive below 40m, do not use this computer for half the things it can do, etc) which are standard issue; others inform the user more usefully about defensive diving and Suunto should be commended for including them. Incredibly, there are still divers who think computer diving is all about strapping on, dropping in and going with the flow. Dive computers and tables are guides for the intelligent, not talismans for the uninformed. There's usually plenty of time to explain how to use them to those who don't know how, when they are in the decompression chamber.

Our test team checked out the 60-odd page manual for ease of understanding and gave it 70 per cent. For once, everyone actually read all of it.

Preparation

Before diving, the user needs to preset the altitude range from one of three ranges between sea level and 2400m/8000ft. Suunto recommends choosing a higher altitude band than needed if the user wants to introduce a greater degree of conservatism. Wetting the contacts manually or entering the water prepares the unit for diving. It isn't possible to dive with the Favor turned off. The computer earned 100 per cent for this safety feature and the fact that it cannot be accidentally turned off between dives; but only 55per cent when we asked if it was possible to enter the water with the wrong altitude setting. In fairness, this would be user error and for sea-level diving would simply result in reduced dive times.

Our testers awarded the Favor 85 per cent overall for ease of pre-dive preparation.