Charles Hood weighs up the latest heated undervests by O'Three and Silent Planet
Heated UnderVest (HUV) O’Three, £695; Silent Planet, £1,100
Modern scuba equipment has led to a large increase in dive times. Only 30 years ago, a dive longer than 25 minutes was considered exceptional, but today, if you carry plenty of gas, dives exceeding two hours are not unusual.The cold, however, remains a problem. While drysuits and undersuits have improved over the years, after an hour or so even the hardiest of divers will start to cool down. More layers will help, but the resulting increased buoyancy can cause more problems.
A solution is to use some sort of heated undergarment. O’Three has developed one such a piece of equipment in the form of an undervest, and we’ve been diving with it since early January to find out how it performs. Silent Planet markets the same vest, but with a Halcyon power pack instead of O’Three’s Custom Divers battery.
Heated undergarments are nothing new: Typhoon brought out its version, the Icebreaker, several years ago (see DIVE, April 2004 for our test). These earlier models, however, usually involved having to make a hole in your drysuit for the battery supply’s cable to pass through.
Inevitably, this led to a weakness and potential leaks; furthermore, in the summer months or when on shorter dives, the connector is still in situ. To solve this problem, O’Three has included a replacement inflation valve/switch. You simply remove your existing inflation valve and replace it with the new one, which is made even simpler if you use an Apeks valve, as it is an identical shape and size. This means you have a way of connecting the battery to your vest without making any modifications to your suit.
In addition, you get an external battery pack and the vest itself. Putting the vest on is simple, and it works well when combined with a thin base layer, with the vest over the top and an outer layer over the vest. You then connect it up to the inner wire and put your drysuit on as normal.
The 12v 3.7Ah (O’Three) or 4.5Ah (Silent Planet) battery pack is shaped like a tube, so you need to store it in a pocket, clamp it to your cylinder, or – as we did – attach to it a boltsnap using tie-wraps and clip it onto a spare BC D-ring. The cable from the battery simply attaches to the outer wire and protrudes through the inflation valve using a waterproof E/O-style connector.
Underwater, all these extra layers did require another 3kg to be added to my weight belt. The majority of our test dives lasted around 60 minutes in a water temperature of 8°C. I’m happy to report that it felt more like diving in 18°C: the vest is excellent and does exactly what the manufacturers say it does. To switch it on, you rotate the outer ring on the inflation valve – it takes a few minutes to warm up. On one particular dive, which involved a lengthy RIB ride, I deliberately saved the battery, only switching the vest on three-quarters the way through the dive. By the time I had completed my safety stop, I had warmed up superbly. And, to the envy of my fellow passengers, I now had a good half hour of battery left for the return RIB journey.
If I owned one of these vests, I would certainly consider upgrading to the larger battery pack at a cost of £180 (O’Three) or £100 (Silent Planet), which gives double the burn time at around 120 minutes. Alternatively, I’d buy a spare small battery or even have a connection from the boat battery for longer RIB journeys. Another option with the larger battery pack is to fit a ‘Y’ connector to allow the use of a Custom Divers lamp head with the O’Three version, or a Halcyon light with the Silent Planet unit.
At just under £700 for the O’Three model and a whopping £1,100 for the Silent Planet version, they certainly aren’t cheap. However, if you regularly carry out long decompression dives, want to combine it with Custom Divers or Halcyon light systems, travel vast distances on a RIB or simply feel the cold, then they are reasonable value for money.
DIVE says...
Comfort throughout the dive – a real winner for divers who feel the cold
O’Three
Value 7 Performance 9
Silent Planet
Value 6 Performance 9
Contacts
O’Three • 01305 822820
www.othree.co.uk
Silent Planet • 01305 826666
www.silentplanet.info