While none of us plan to fall off the boat or get lost in the mountains, we all know it is smart to prepare for such an emergency.

Indeed, boaters have a number of ways to track the missing: man overboard or MOB alarms and Emergency Position Indicating Radio Beacons (or EPIRBs), among them.

Another option that is growing in popularity, not only among boaters but among hikers, campers, mountain climbers and others who venture to remote areas, is the Personal Locator Beacon (PLB) – radio transmitters that communicate with orbiting satellites to send distress messages.

In most cases, these satellites are part of the COSPAS-SARSAT, an international satellite system that operates in both geostationary and low-earth orbits to provide world wide coverage. The satellites receive emergency messages and forward them to search and rescue personnel. The United States Coast Guard handles rescues on the water in the United States, while a joint organization was established to handle the terrestrial calls on land.

ACRThe ACR AquaFix comes in two models. The AquaFIX I has an interfere to an external GPS signal while the AquaFix I O has both an internal GPS as well as the external interface. Most PLBs transmit on the same frequencies as the full sized EPIRBs: 406 MHz. They also transmit on 121.5 MHz. This frequency is used as a homing signal by rescue teams. Other manufacturers use a different scheme, contacting commercial orbiting communications satellites.

PLBs are registered to their specific user. Registration is critical because it provides information about the owner and points of contact. Earlier this month the Coast Guard issued a marine safety alert urging nearly a quarter million boat owners to make sure their EPIRBs and PLBs are correctly registered with NOAA. They cited delays in identifying a scallop boat with an incorrectly recorded beacon number that sank in the Atlantic Ocean in March.

OPERATIONAL DETAILS

There are three major manufacturers of PLBs: ACR, McMurdo and Spot. The first two use the COSPAS-SARSAT satellites, while Spot uses commercial communications satellites. Some models also incorporate a GPS receiver or allow GPS data to be input. This provides an exact location when a distress signal is sent.

The GPS-equipped models are self contained, requiring no additional input to determine the location. The downside is that emergency distress calls will be delayed until the GPS successfully acquires the needed satellites and calculates a location. The models that allow input from an external GPS can transmit a distress signal sooner, but having a PLB connected to a handheld GPS may be unwieldy – especially in an emergency.

A critical difference between EPIRBs and PLBs is the amount of battery power available to the user. Being a small, handheld unit, a PLB will not transmit for as long as a full sized EPIRB. As such, PLBs are better suited for land or near coastal areas than long distance offshore voyaging. The typical PLB battery is made of lithium and is good for approximately five years. The actual transmit time when activated is generally 24 hours.

ON THE SPOT

The Spot Satellite Messenger operates on a different model than a typical COSPAS-SARSAT based PLB. The Spot unit communicates with commercial communications satellites in orbit. A distress signal is transmitted to a commercial organization handling Spot calls, the GEOS International Emergency Response Center, which relays the information to the appropriate authorities.

That third party arrangement allows the Spot unit to provide four additional services over and above the typical PLB.

The first is the typical distress call, called "alert 911." Activating this function on the Spot unit transmits a distress message every five minutes until cancelled. When GEOS receives the message they contact the Coast Guard, police or other available authorities – even embassies. They also reach out to the emergency contacts listed in the user's registration.

ACRThe ACR ResQfix is smaller and lighter than the AquaFix models. It has an internal 16-channel GPS and requires a flotation pouch.It is important to note that the COSPAS-SARSAT organization does not monitor these calls. Distress calls must be routed, by GEOS, to the appropriate agency. That process may take more time than processing the signal from a typical PLB unit.

The second function is called "Check In." When this function is activated, the Spot unit determines the user's location from the GPS satellites and transmits a message giving coordinates. That message can be sent to a list of friends and family. It can also be sent to a Google Maps page, graphically displaying the user's current location. The waypoints can be retrieved at a later date.

The third function is "Track Progress." When this function is selected, the Spot unit calculates the GPS location and sends a message. It sends a new message every 10 minutes with the user's updated location, which can also be displayed on Google Maps, offering real-time tracking. The unit will transmit these updates for 24 hours.

The final function is "Ask For Help." This is used to contact the user's team in the event of a non-life threatening situation. It will notify the contacts set up in the user's profile, alerting them that help is needed. That call can also be routed to a cell phone or to Google Maps to show a current location. In the event the Spot unit cannot "see" enough satellites to determine an exact location, it will still send the help message.

When it comes to hardware, Spot only has one model in its lineup, the Sport Satellite Messenger. This unit is about four inches high and almost three inches wide, and weighs about seven ounces. It comes with a one-year warranty and the unit floats. The MRSP is $169 for the basic unit but can be found discounted to $149. Some retailers, West Marine for example, also offer rebate coupons for various subscription services.

This is an area where Spot pricing differs for the typical PLB. Spot services require a yearly subscription. The basic fee is $99 a year and includes the Alert 911, Help and Check In features. Additional services for tracking, product replacement and a roadside assistance program cost extra. There is also a GEOS Search & Rescue insurance package available. Priced at $7.95 a year, this provides up to $100,000 for additional search and rescue resources each year. Those funds could be used for expensive items like helicopters and ground search teams.

MCMURDO'S FAST FIND

McMurdo's new Fast Find 210 won an Innovation Award in the safety gear category at this year's Marine Aftermarket Accessories Trade Show in Orlando. This unit is the size of a small cell phone, about four inches high, almost two inches wide and weighing just five ounces.

Amazingly, this compact unit contains an integral 50-channel GPS unit, ensuring quick and accurate fixes. The unit is rated waterproof to 33 feet for 30 minutes and battery life is rated for five years. One down side – it doesn't float, so you want to consider the optional flotation pouch.

One feature unique to the Fast Find 210 is a built-in LED strobe light. When activated, it flashes the Morse Code signal SOS. For an in-depth test and review, check out the Panbo Marine Electronics Blog; it comes very highly rated. The manufacturer's suggested retail on this unit is $299.

MCMURDOThe McMurdo Fast Find 210 is a small as a cell phone and is highly rated. It has an internal 50-channel GPS unit.ACR OFFERINGS

Among the offerings from ACR is the AquaFix GPS I. This basic unit is about six inches high and three inches wide and weighs about 12 ounces without its carrying holster. The holster provides a convenient way to attach it to a PFD, jacket or belt. Its lithium battery has a five-year replacement life and an 11-year storage life (let's face it – with the rapid development of marine electronics, most units will be replaced before needing a new battery.) It is waterproof to 18 feet for an hour and to 33 feet for 10 minutes. It also floats.

This unit has a GPS interface, meaning that GPS location information will need to be provided from an external handheld GPS unit. The manufacturers suggested retail price is $540 but it is available for about $360.

The ACR AquaFix GPS I/O is the same as the AquaFix GPS I, except that this model has an onboard GPS unit, as well as an interface for an external GPS. The unit can be purchased, with discounts, for about $499.

Another ACR unit is the ResQFix. This is the smallest and lightest of the ACR PLBs. It is about six inches high, two inches wide and weighs a mere 10 ounces with its lanyard. Like the other ACR units, it has a lithium battery with the same specs and its waterproof ratings are roughly the same, though it requires a floatation pouch to remain above water. The onboard GPS unit is capable of 16 channel parallel operation, resulting in quick and accurate fixes. The unit can be purchased, with discounts, for about $520.

CHOOSING A UNIT

While PLBs are great, you probably don't want to consider one of these units as your sole device for offshore voyaging.

For that application, select a full size EPIRB with their larger battery capacity and longer transmit times. PLBs are more suitable for inshore cruising along with on-land uses such as hiking and river travel – and there they make a cost-effective addition to your bag of safety items.

If the ability to post your location and trip information to a Google Maps page intrigues you, pick the Spot Satellite messenger. Spot has received a lot of attention, and the Spot website is full of information on the unit, the service and the community that surrounds it.

As far as the best all-around choice, the McMurdo Fast Find 210 offers a great deal in a small unit, and it does so at a reasonable price. As Ben Ellison, senior electronics editor for Bonnier Marine Group, editor of the Panbo blog and a judge at the Innovation Awards, put it, "McMurdo puts a high-performance PLB within the budget of even the casual boater."

At that price, there is no reason not to equip everyone aboard with one"”then add a Spot for those neat Google Maps.

MIKE WAGNERThis is an actual screen shot of a Spot CHECK IN message posted to a Google Maps page.