Beowulf has a five year old Litton 406mHz EPIRB. Even though the theoretical life of the lithium battery is ten years, regulations require that they be replaced every five. We’ve been told that these are no longer being made and the batteries are not available – so, we’ve been checking out replacement units.

Does one even need a 406mHz EPIRB? This is a question of where you sail, your thinking on self-sufficiency, and of course budget. The 406 units are such an improvement over pervious technology that for us, we feel the $800 or so investment is worthwhile. We can see two scenarios where an EPIRB might be needed. The first is if there is a major security problem (there was an incident a couple of years ago where a yacht was boarded in a European port – the crew triggered their EPIRB – and the local police were at the dock within 20 minutes). The second issue is fire. That’s the one situation where we could see ourselves getting into the liferaft.

The equation has been muddied somewhat by an even better mousetrap – an EPIRB with a built in GPS (GPIRB). Where the standard 406 EPIRB is accurate to 3km (28 square km of area) the GPIRB is accurate to 100 meters! Of course this comes at a price – about double the plain vanilla version.

There have been some attempts at a semi-GPIRB – where the GPS is external and wired to the EPIRB. This will give you a GPS position input (if everything goes right) on the first cycle. But thereafter you have a normal un-GPS’d EPIRB.

GPIRB accuracy chart.

Two companies are currently offering the GPIRBs. Paines and Wessex, an English company, and Northern Airborn Technology. We asked John Lindstrom (electronics guru at Baytronics South) if he favored one over the other. John’s answer was the National units were the best at present. Baytronics sells the standard 406 EPIRBs for about $800. The GPIRBs go for around $1600. Is it worth the extra $800? The way to answer that is to ask yourself what you would pay for the extra accuracy or time savings it theoretically engenders in a rescue situation – as you are stepping into the life-raft. (You can reach Baytronics at www.baytronics.com .)

While we’re on the subject of EPIRBs a couple of other issues need to be mentioned. One is that EPIRB registration must be updated every two years. (For more on this, see our Tech Talk article on EPIRB registration.) Second, your EPIRB should be tested monthly or before every long passage.

The third issue deals with the radio “ground plane”. For 406mHz signals a ground is not required. However, these units also broadcast on 121.5mHz which is used as a homing signal by rescuing ships and aircraft. The 121.5 works much better if the EPIRB is in water. Is this enough of an issue to leave the EPIRB floating on its tether outside the raft, or alongside the boat? That depends on sea state and the risks of losing the EPIRB. If you have a VHF radio and are in contact, then it is probably best to keep the EPIRB where it is safest.

Is there a middle ground between the two systems? Assuming you have a portable GPS (with extra batteries) and a portable GPS (also with extra batteries) you have the potential to talk to your would-be rescuers and give them your coordinates. Is this as good as a fully automatic system? Of course not. But since the odds are you already have the portable GPS and VHF, and the odds of using the GPIRB are low, it may be a worthwhile tradeoff (note-keep lots of extra high quality batteries vacuum packed or zipped in baggies – packaged in sets of four – in your emergency grab bag).

What sort of a unit are we going to get to replace our old EPIRB? We’ll let you know when we decide. We need to think about the price/performance issue a bit more.

Posted by Steve Dashew  (March 2, 2001)