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October 21, 2011

Advances in Night Vision

How thermal and low-light cameras aid piloting and fishing

By contrast, thermal night vision depends on the heat that every object emits and heat that reflects from objects. Thermal wavelengths can also penetrate smoke, light fog and haze, though they are inhibited by rain and soaking fog. In addition, thermal cameras can’t see through glass and isinglass; however they can see through glare on the water, because glare is reflected light not heat.

A thermal camera detects infrared radiation in the wavelength range between 7 and 13 micrometers. The camera’s detector material (vanadium oxide for FLIR products) absorbs the radiation and begins to heat. The resulting change in electrical resistance is the basic sensing technique, according to FLIR.

“Everything gives off heat,” Teich says. “You may find a semisubmerged log, and that will have a different temperature than the surrounding water, and the thermal camera will allow you to see it.”

Safe and Secure

Most mounted night-vision cameras range in price from $5,000 to more than $100,000. FLIR’s handheld First Mate MS thermal units — released this summer — start at $1,999. They differ from the original First Mate series because they’re scopes rather than cameras, allowing users to view but not record images.

Cameras come in a range of ­resolutions and lenses that generate narrow to wide fields of view — though thermal cameras can see greater distances than low-light cameras — and with different refresh rates. With a handheld or lower-range, fixed-mount camera, anglers might see a lobster pot at about a half-mile, a small boat at about a mile and a larger vessel at about five miles. With higher-performance systems, users might triple those distances, or even multiply them by 10 with top-of-the-line gear.

Camera companies produce a variety of pan and tilt options for the mounted camera heads, as well as several control setups. FLIR, which acquired Raymarine last year, has integrated its controls into Raymarine’s E-Wide and G series multifunction displays. OceanView has worked with Furuno to create onscreen controls through NavNet 3-D units.

DeCosta, who uses Raymarine C-series MFD units, operates his M-Series camera with a joystick. Besides using the camera in fishing situations, he simply finds it helpful when navigating to and from the tuna grounds. “I have a two- to eight-hour run depending on where the tuna are,” he says. “This year, I fished Georges Bank — a 140-mile run. I point the camera straight off the bow; it’s amazing — you can run right through a lot of lobster gear and high fliers (commercial-longlining gear) in the water.”

In port, he can navigate unlit harbors using the camera instead of just his radar. “The night-vision camera took all the guesswork out of it,” he says. “It’s just like running in daytime.”

What’s next in thermal-camera evolution? Teich says to look for dual-use systems that combine ­navigation with home-port security. Once you’re safely back in your slip, your thermal camera becomes part of an alarm system that draws an imaginary trip wire around your vessel.