Features July 15, 2003 Issue

406 MHz EPIRBs

The ACR Global Fix 406 with internal GPS is the top pick, followed by the Pains Wessex SOS Precision. The NAT Satfind lacks an integral GPS, but has a user-changeable battery.

For those who regularly venture far enough offshore to make a mayday broadcast via VHF questionable—and this isn't many miles for small boats outside line-of-sight range—a 406 MHz EPIRB should be given serious consideration as an additional safety device. 

We took these three EPIRBs to the Coast Guard in Miami for testing. From left to right: The Pains Wessex SOS Precision 406, the NAT Satfind 406 Pro, and the ACR Global Fix 406.

Since our last EPIRB evaluation nearly four years ago (October 15, 1999), much has changed. The most significant difference has been big price drops. Our top pick in 1999 was an NAT unit with a street price of about $2,000. Today, a unit with the same capabilities sells for half that.

How They Work
First, a bit of review. An emergency position indicating radio beacon, or EPIRB, is a transmitter that when activated sends a distress signal via satellite that eventually reaches a search-and-rescue (SAR) unit. EPIRBs vary in capability, and those that operate on the 121.5/243 MHz bands are by far the least expensive and least capable. Satellites can pick up their transmissions, but because of frequency congestion, analog signals, and a lack of a unique identification, they have a high false alarm rate. Only about two out of every 1,000 alerts are real. This causes very long delays in search-and-rescue efforts and unduly taxes SAR units. The USCG does not recommend their purchase and plans to phase out the 121.5/243 MHz EPIRB by February 1, 2009.

Newer EPIRBs in the 406 MHz band transmit digital signals to the satellites, which allow the transmission of additional data, including a UIN (unique identification number). When coupled with proper registration, the UIN allows rescue agencies to confirm the need for assistance prior to launching expensive SAR assets. The upgraded capability of the 406 MHz EPIRB has reduced false alarms to a more reasonable rate: One out of 12 are real. Plus, about three quarters of the 11 false alarms can be confirmed false prior to launching SAR units.

The latest incarnation of the 406 MHz EPIRB contains an internal GPS receiver to increase position accuracy. In addition to the UIN, a GPS-equipped EPIRB also transmits the unit's latitude/longitude coordinates. The Coast Guard recommends this type of EPIRB.

A cooperative effort by Canada, France, Russia, and the U.S. initiated the satellite reception system that is known today as the COSPAS/SARSAT GEOSAR system. Today the system is a combination of low-earth orbiting and geostationary satellites.

We'll use an on-water example to explain how the system works. Let's say a crew activates their EPIRB because the boat's on fire. Since the crew's EPIRB is GPS-equipped, the beacon's UIN as well as its position is transmitted to the satellites and relayed to the appropriate SAR agencies. A USCG SAR unit would respond with a call to the vessel owner for confirmation that the vessel was actually at sea.

The Coast Guard has numerous options, depending on the vessel's location. The CG could divert an already-airborne aircraft; it could launch a helicopter or utility boat, or it could radio a nearby AMVER vessel to render assistance. (AMVER is a system adopted by commercial ships at sea to report their positions regularly, so that rescue agencies can divert the nearest ship to a distress call. This, of course, increases the safety of AMVER vessels, too.)

With the transmission of good lat/long data to rescue authorities, response time averages only 25 minutes. That type of quick response is simply not available without a GPS built into an EPIRB.

With a non-GPS equipped EPIRB, the satellite system generally requires at least 45 minutes to calculate the position of an activated beacon. Plus, once calculated, the position is not as accurate as the transmitted position of the more sophisticated GPS EPIRB. The USCG estimates that the area needing to be searched with a position-reporting EPIRB is a mere .008 square miles. But with a non-position-reporting unit, the search area increases to 12.5 square miles. In rough seas, or restricted visibility this is a big difference.

Another scenario that illustrates the value of a GPS-equipped EPIRB: If you travel far from the shores of the U.S., the Coast Guard may be unable to reach your position quickly. This would likely necessitate the diversion of an AMVER vessel to your reported location. This vessel may not have the search capabilities of more sophisticated Coast Guard units, and be unable to find you in a search area as large as 12.5 square miles.

Certification of an EPIRB is highly regulated; specifications from COSPAS/SARSAT, the FCC, and the USCG all apply to units built for operation in the U.S. Both market pressure and the tough certification process force some commonality among all the units we tested. For example, all units are equipped with a 121.5 MHz continuous-duty homing transmitter, albeit of various output power. A strobe light is integral to each, as well. The brightness of each is a minimum of .75 candelas with a flash rate just over 20 times a minute.

Environmental certification can be either Class 1 or 2; we tested units in both classes. Class 1 has a wider temperature operating and storage range, which makes certification more stringent. Battery certification standards require a unit to operate for 48 hours at its lowest certified temperature. All units come equipped with a mounting bracket and lanyards. They all float unassisted, and will activate automatically when they hit the water. A self-test capability is also required. A differing series of beeps, flashing or steady lights, or a quick strobe flash indicate a passed or failed test. Reading the owner' s manual and being familiar with your unit's test procedure is essential, as the USCG requires the test to be performed by the owner or operator every 30 days.

What and How We Tested
We obtained three EPIRBs from three different manufacturers. One GPS-equipped unit came from ACR Electronics of Ft. Lauderdale, the Global Fix 406. A Canadian company, Northern Airborne Technology, sent us its Satfind 406 Pro, a non-GPS equipped unit. (This unit is also sold as the Profind 406. Both are manufactured by Seimac Limited, Dartmouth, NS, Canada. PS readers may recall Mailport exchanges a couple of years ago in which the ProFind 406 was reported to be the only EPIRB available whose replacement battery could be bought and installed by owners at a reasonable price.)

Both ACR and NAT operate as separate companies under the Chelton Group umbrella. The winner in our last test was a unit from NAT called the GPIRB, which is no longer in production. The only GPS-equipped unit available from NAT today is a rebranded version of the ACR unit already included in out test.

McMurdo Pains Wessex, with headquarters in the UK, supplied us with its GPS-equipped SOS Precision 406 EPIRB. In total, we tested two GPS-equipped units and one without. (To more fully cover the market, we also included data in our table on non-GPS equipped units from both ACR and Pains Wessex: the ACR Satellite 2 and the PW Rescue 406.)

We arrived at our findings by considering each unit's cost, each unit's battery replacement cost and down time, warranty, and GPS capability. We took all three to the USCG in Miami to actually activate each one using the Coast Guard's test equipment. The test equipment records the broadcast frequency, checks that the signal meets certain parameters, and displays the data that is sent. In this case, the UIN number was sent without GPS data. The USCG testing gear actually restricts the internal GPS units from receiving a signal so this information is not broadcast.

ACR Global Fix 406
The ACR Global Fix is priced at $874.95 for the manually deployed, Category 2, configuration. As the name Global Fix implies, the unit contains an internal GPS receiver and broadcasts its digital signal on 406.025 MHz. All the units tested were about the same size; this beacon is 4" x 5" square with a height of 9". The antenna adds another 7.5".

A yellow plastic case with a translucent top and a lanyard on a spool located on the rear of the unit contain all the electronics and the battery. Activation is accomplished manually by flipping a lever on the top of the unit. Certification is in the more stringent Class 1 temperature range.

A battery change in the Global Fix does require sending or taking the unit to the factory or an authorized service center for replacement. The procedure, according to Chris Wahler, ACR director of marketing, entails more than just replacing the battery.

"We test the electronics, replace the seals, inspect the case, replace the battery, and finally pressure-test the unit to make sure it is watertight." Wahler also said the whole process can be accomplished for a factory walk-in customer in a couple of hours. Normally units are mailed in and require about five days at the factory or service center. With shipping time included on both ends you should be able to get a unit serviced in less than two weeks at a cost of $312, plus one-way shipping costs. That cost is the factory list price. You may be able to find a slightly lower cost at an authorized service center.

This unit carries a 5-year limited warranty. It passed accuracy testing at the USCG station.

Bottom Line: We'd certainly like to see a lower battery replacement cost for this unit. However, when amortized over 5 years, the difference between this and other units amounts to around $20 a year. We can accept this small additional cost for such a top-quality unit that has one-step operation, a reasonable price, an internal GPS receiver, and Class 1 environmental certification. Our top pick.

Pains Wessex SOS Precision 406 GPS
At $842.95, the SOS Precision 406 from Pains Wessex is slightly less expensive than the ACR unit. Its triangular yellow case contains its internal GPS, all other electronics, and the battery. The unit measures 8.5" in height, and has a clear top that's topped by a 7" antenna. The lanyard is wrapped around a 1.25" detachable plastic tab on the rear of the unit. It broadcasts its signal on 406.028 MHz and passed USCG testing.

To activate manually, you slide a tab to one side and push a button. Environmental certification is in the less stringent Class 2.

A battery change on the PW unit requires shipping the unit to an authorized service center. Replacement costs $200, plus one-way shipping.

The manual accompanying the unit states the warranty period is one year, which we think is too short. Both a company spokesman and the company's U.S. advertising brochures indicate that the company will back the unit for up to five years, but it would be good to have this confirmed in the official literature.

Bottom Line: The warranty period is a big issue in overall cost. Without being sure, we'll rank this slightly behind the ACR unit.

NAT Satfind 406 Pro
At $672, the Satfind Pro is the least expensive unit tested. Its lack of a GPS accounts for its lower price, but when compared price-wise with other non-GPS equipped units from ACR and Pains Wessex, the Satfind is actually about $100 more expensive. The 406 Pro's case is round and about 4" in diameter. Height is slightly over 8", with nearly 7" added by the antenna.

The case is yellow with a nearly clear top; its lanyard is wrapped around the middle of the unit and clearly visible. Two switches are located on the top of the unit, one for testing and the other for manual activation. This unit carries a Class 1 environmental certification.

The battery system is rather unique, according to George Lariviere, vice president of NAT: "The batteries are sold through our dealers," he said. "The present retail cost is $199.99. However, since they last five years, only the people who turn them on for a real emergency need to change them. The Satfind Pro is the only unit that has been tested for compliance with a user-changeable battery. This EPIRB complies with all regulations in both Canada and USA, plus many other countries. We built it expressly [to have a] user-changeable battery. When you change the battery you are also getting all new water contacts, O-ring seal, keep-off reed switch, new lower plastic base section, new lanyard. So your EPIRB will look brand new again, and the new battery is good for another 5 years."

We were able to find the battery kit on the Internet for $150. This unit carries a 5-year limited warranty.

Bottom Line: If we were to choose a non-GPS unit (strictly because our budget would not allow the purchase of a more expensive GPS-equipped unit) we would opt for the Satfind Pro because of its sturdy construction, reasonable price, and user- changeable battery system.

On vessels required to carry EPIRBs, the Coast Guard now recommends that those units be equipped with GPS. We would add that the GPS option, although an added expense, makes sense for everyone who gears up with an EPIRB. After all, this is your last-ditch mayday device, for use when you have a big, bad problem on your hands. If you ever have to use it in earnest, that extra couple hundred dollars will seem like money extremely wisely spent.

Our top pick to fill the bill is the ACR Global Fix. Our second choice would be the McMurdo Pains Wessex SOS Precision 406, and it would really be a toss-up with the ACR if the warranty situation were less murky.

If budget constraints simply won't allow the purchase of the more expensive GPS-equipped units, NAT’s Satfind 406 Pro is the natural choice because of its user changeable battery. Over the life of the unit, the less expensive battery will more than make up for the higher initial purchase price. Plus, there's no downtime when you can simply order the new battery and install it when it arrives.


Also With This Article
Click here to view "Value Guide: EPIRBs."
Click here to view "Auto or Manual?"

ACR Electronics, 800/432-0227, www.acrelectronics.com
Northern Airborne Technology, 800/225-4767, www.nat-inc.com
Pains Wessex, 973/575-8811, www.mcmurdo.biz

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