What’s a Heated Vest, and Should You Buy One?

In this story on Kona diving, our reporter envies the heated vests she sees fellow divers wearing, and how toasty they look while wearing them in those cool waters. Are these battery-powered vests worth spending up to $1000 on? John Bantin, our veteran dive gear tester, has tried on a few, and here are a couple of his picks sold in the U.S.

The Thermalution Compact Dive Series (70mm): "I first tried this out in the some-would-say balmy Caribbean waters of Grenada in the Caribbean. (Am I a man or a mouse? Squeak!) The undervest worked well under my wetsuit. It's made of a Lycra-like fiber, and has a non-metallic heating panel built into the back. Two pockets take the twin battery-packs, the size of a cigarette case. They're connected to the vest via cables with wet-connectors. Strangely, the designers have put the receiver unit for the wireless connection in the small of the back, so you wear the vest under your suit, and the controller straps onto a forearm. There are three progressive settings, and an LED indicator that goes from green through orange to red. To confirm that the receiver is working, it vibrates for a second, twice for the mid setting, and three times for the highest heat setting. It gives a single long vibration to confirm it's shutting down -- it's a bit like having a small mouse inside your suit with you.

"The controller's battery life is around 18 months, so I guess that will be an ongoing expense when the time comes to replace it, because it is factory-sealed. The main batteries are simply disconnected from the suit and reconnected to a multi-voltage intelligent charger. They take around eight hours to fully charge, and are claimed to be good for around 500 recharges. A fully charged pair of batteries are said to last for between three and four hours, so that should be enough to suit even the most adventurous diver." ( $500; 2.5 pounds; www.thermalution.com )

Typhoon Icebreaker: "High-tech in design but low-tech in operation. It uses a flexible intelligent polymer containing thousands of conductive carbon particle chains in panels within a neoprene vest, which, with the aid of Velcro-covered sections, can be adjusted to fit almost anyone. Power is supplied as a rapid pulse. The designer promised it could be completely soaked and, as it contained no electrical components, would still work safely. The current flows and it gets warm. It's that simple. It uses so little power to heat up that a relatively small 4A/h lithium-iron battery is used. That holds enough charge for around 70 minutes and more - but you don't switch it on until the last part of your dive, or you carry more battery power. Once the material reaches a certain temperature, it self-regulates. The conductive particle chains in the suit vibrate when the current flows. They get warm but the material that forms the heating element will not exceed 108 degrees Fahrenheit - warm, but not warm enough to cause discomfort.

"With no thermostat, how do you turn it on and off? You must adapt your wetsuit or drysuit by punching a 13mm hole through its fabric to fit the electrical connection. On the inside of this waterproof bulkhead connector is a lead and plug that connects to the heated vest's lead. On the outer side is a two-pin (plus guide-pin) waterproof connector. Mount the battery-pack where you wish and feed its lead to this. Connect when you get cold. Disconnect if you feel too warm. The wet-connector comes with a blanking plug-end to the battery lead to stop unwanted discharge through the water over the longer periods when it may not be connected. The battery-pack is small enough to fit a BC pocket. The best place to fit the bulkhead connector is on a thigh, as you can see it and get to it easily." ( $1,000; 0.44 pounds; www.exo2theheatinside.com )