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For a long time, seeing in the dark was a pipedream put in the same column as eternal youth and sure-thing investment opportunities. Times have changed—at least for the first in this list of fanciful quests—thanks in part to infrared (IR) technology and the gear it has spawned. The military and law enforcement were the first to put IR technology to use. FLIR, a pioneer in the creation of portable IR scopes, recently purchased Raymarine and is delivering to the recreational marine market infrared technology that already has grabbed the attention of SEAL Teams, Delta Force operators, and security firms across the country.
At the heart of FLIR’s approach to seeing in the dark is a sensor that works like the charge coupled device of a digital camera. The big difference is that the FLIR sensor responds to the infrared end of the spectrum and ignores visible light. The FLIR sensor reacts to very minute changes in radiated heat energy—sensitivity is about .05 degrees Celsius, an extremely high rating, akin to hearing a half of a pin drop—which causes a proportional change in circuit conductivity. The correlation between infrared energy and electron flow in a micro-chip circuit is amplified and fed to a digital display.
Practical Sailor reviewed FLIR’s previous thermal-imaging camera geared toward the recreational marine market in the June 2008 issue. Testers found that the Navigator II, a mountable, thermal-imaging camera, offered valuable information for sailors, but that it should not be seen as a replacement for radar. Priced at $5,000-$9,000, that device was a bit of overkill for most boat owners, but the company’s follow-up offering, a handheld thermal-imaging camera dubbed the First Mate, is sized and priced more appropriately for typical cruisers. PS testers put the HM-324 XP+ model of the First Mate through its paces recently to see whether it would be a valuable tool in a sailor’s navigation or MOB-recovery toolboxes.
Night-vision vs. FLIR
Devices that allow users to see in the dark are not new. The technology has been around for nearly 50 years, when U.S. military forces used the earliest light-gathering night-vision scopes (Generations 0 and 1) in World War II and later in the Vietnam War. Military need—and funding—advanced the technology through the ’70s (Gen 2) and ’80s (Gen 3), and the latest scopes—called Gen 4 on the consumer market—are much improved over those of decades ago. However, it’s important to understand that all night vision scopes need some light to work. The Gen 3 scopes are quite happy with starlight (hence the nickname “starlight scopes”). The Gen 2 units work best with moonlight, and Gen 1 devices must have additional IR illumination, typically built into the scope.
Thermal-imaging technology has been around nearly as long as starlight scopes, but it was slower in making its way to the consumer market. There are some notable similarities and differences between the Gen 0-4 night-vision scopes that work by gathering available light and the thermal-imaging FLIR cameras, which respond only to infrared energy. Both indirectly display energy radiating or reflecting from objects in their field of view. Both have an optical lens that focuses energy onto a sensor or image enhancer and can make use of either telephoto or wide-angle views.
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The IR sensor converts heat information into an image seen on a screen in the viewfinder. The light-gathering night-vision scope, however, utilizes a cathode-based photon-to-electron light-intensification process—turning electrical energy into light energy—and displays the image on a phosphorous screen.
Photos by Ralph Naranjo
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The infrared unit’s sensor reacts to radiated heat, and the digital display can even be networked. If the ambient visible light drops below the sensitivity threshold of a night-vision scope, the unit ceases to function. Because all starlight scopes need some light to work, many of the units also contain an IR illuminator that can act like a non-visible flashlight beam. The inclusion of such an illuminator does not make it a thermal-imaging device; it merely allows IR-reflected light to illuminate an overly dark scene.
Photos by Ralph Naranjo
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Infrared scopes do work on the darkest nights—or, for that matter, in an unlit coal mine a mile below the surface. The hyper-sensitive sensor reacts to minute heat differential. The radiated thermal energy falls just below visible light on the electromagnetic spectrum, and acting like a book end, it teams up with ultraviolet light, sandwiching all the colors of the rainbow between the two. In essence, the IR sensor responds to radiated heat.
The amazing thing is how little variation in temperature causes a contrast on the monitor. This was exemplified in PS tests when testers set a small black-furred Schipperke (Belgian barge dog) loose in a pitch-black room and tried to detect him using the FLIR First Mate. Not only was the dog easily detectable, but testers could see the footprints he left behind due to the miniscule heat transfer that took place with each step.
In the June 2002 issue, Practical Sailor tested an array of starlight scopes available to sailors. The 11 products covered a range of designs and technologies (Gens 1-3). The top pick in that test was ITT Corp.’s Night Vision Mariner 160, a Gen 3 monocular that testers reported to be functional and ergonomic while offering bright, crisp images. That scope has since been discontinued, but realizing that many are still in use on serious cruising boats, we figured the Vision Mariner 160 would be a good measuring stick for the FLIR First Mate in target-spotting tests.
How We Tested
Firm believers in the importance of seeing how a product performs in real-world applications, we took the First Mate field test straight to the water on a moonless night to see just how much of a navigational aid thermal imaging could be.
We set up a series of discernment tests based upon what we assumed would be tough targets to detect. Because contrast is based upon temperature differential and the density of thermal energy radiated, we chose objects that would theoretically not be much different in temperature than the surrounding water. We predicted that at night, small buoys, sand spits, and crab pot floats would radiationally cool rather quickly—causing them to become very similar in temperature to the surrounding sea and making them harder to spot. We also assumed that a human being in cooler water might be a prime target to find with an IR scope.
Setting the FLIR unit in the “white” hot mode, we went about our infrared treasure hunt, ranking how well certain objects, all unseen by the naked eye, showed up under FLIR scrutiny. We noted the influence of ambient light, and ranked it as none, minor, or major, the latter being situations where bright pier-side or shoreside light sources backlit a dark sea. Testers used the ITT Gen 3 starlight scope to spot the same targets in the same conditions with very little luck.
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What We Found
A lightweight, easy-to-hold monocular, the First Mate has a simple one-button push start up procedure. It’s not an instant-on device and takes 90 seconds or so to stabilize the sensor and become fully operational.
The image in the viewfinder is black and white with good contrast and detail. By no means does it turn night into day or offer a high-definition rendering of all that surrounds the user; that’s still a few generations away. What a user does get is a very discernible image of what’s close at hand and a very good hint of what lies ahead.
Testers found the unit to be ergonomically designed and easy to handle, and its splashproof protection is adequate for on-deck use. The “buttonology” is very straight forward, with a power button that toggles through on, stand-by, and off; another pushbutton selects still-picture capture or video control. The low-resolution still camera function stores images on a removable SD card and also allows video clips to be recorded. Testers found this to be an interesting feature, but the resolution is pretty minimal. We preferred keeping the electronic zoom control set at the wider angle field of view.
The unit is powered by four, rechargeable 1.2-volt DC Ni-MH AA batteries. The charging system, which incorporates an attachable “hot shoe,” malfunctioned in the unit we tested. We found out in a follow-up conversation with FLIR that some of the early units had charger connection issues that have been resolved. The unit also happily operates on four AA Alkaline batteries, always a good backup plan, but due to the fairly significant power requirement, the rechargeable approach is much more cost effective. We found that the operating time was between four and five hours of continuous use with well-charged Ni-MH batteries. The standby mode delivered approximately 110 hours of instant-on readiness.
As the results in the Value Guide show, the compact First Mate exceeded testers’ expectations when it came to target discernment. Objects that we thought would be too close in temperature to the sea surface, like crab-pot floats and small metal buoys, stood out just fine. Apparently, the difference in material composition results in small variations in how they radiate heat. There was even enough energy refraction to show wavelet ripples on a sea surface of uniform temperature. In short, the issue of not having enough temperature differential between an object and the sea was not a problem at all.
Another big plus was that in strong background lighting situations, the unit was not plagued by bright hot spots. We found this to be a major issue with available light-gathering starlight scopes. The FLIR unit showed none of the potentially damaging light bloom response that visible light-gathering devices suffer from. The bright shoreside illumination was outside the IR spectrum, and it did not hamper FLIR vision.
Comparing the FLIR First Mate with its big brother, the gimbaled M Series, we came away with a junior varsity versus varsity experience. The big screen view and greater sensitivity and selectivity of a mounted, image-stabilized IR camera outshined—or perhaps we should say “out scrutinized”—the darkness. However, it did not nullify the value of the handheld unit. All it takes is a moonless night and a return to a lobster pot-infested Northeast harbor in order to drive home the value of seeing in the dark.
The final part of our testing boosted our rating of FLIR’s First Mate from a functional gadget to a serious piece of safety equipment. What tipped the scale was the unit’s propensity to locate a person in the water. The human head, hands, and arms radiate heat at a significant rate, and the First Mate is just right for finding such a needle in a high-seas haystack.
Conclusion
Not many sailors fall over the side, but when it happens in a nighttime context, all bets are off. In our previous tests of MOB beacons (PS, May 2008), we have evaluated gadgets that announce some one has fallen overboard and others that locate a radio beacon the victim is wearing—if they have it with them when they went over the side. There are even small 406 PLBs (PS, December 2003) that send signals to satellites, but the First Mate offers a chance to spot an individual in the water, regardless of whether or not they were armed with a transponder when they went over the side. Search-and-rescue helicopter pilots are vectored to EPIRB and PLB signals, but often their final approach to the victim is made with infrared imaging.
As a tool for navigation, the FLIR First Mate is an added bonus when used with radar, but its price keeps it out of reach for most sailors. The basic model (HM-224) starts at $2,500, and the high-end model (HM-307 XP+) can cost upward of $6,000. However, where the First Mate really has value and increased versatility is as an MOB-recovery aid and that makes the pricetag a bit more palatable—especially considering that less versatile Gen 3 and Gen 4 starlight scopes can cost $1,500 to $4,000.
