Six per­sonal AIS res­cue bea­cons com­pared

six man-over­board AIS lo­ca­tor bea­cons to see how they per­form against each other

Motorboat & Yachting - - Contents -

Emer­gency Po­si­tion In­di­cat­ing Res­cue Bea­cons (EPIRBS) and Per­sonal Lo­ca­tion Bea­cons (PLBS) are vi­tal pieces of equip­ment for cruis­ing off­shore, but if you fall off a coastal­based mo­tor boat, they lack one key func­tion – they don’t com­mu­ni­cate your po­si­tion to the boat you’ve just fallen from. A Search and Res­cue Transpon­der (AIS SART) shows your po­si­tion, speed and course over the ground on the chart­plot­ter in front of your re­main­ing crew, and any other ves­sel or sta­tion able to re­ceive AIS within the SART’S range.

HOW DOES AN AIS SART WORK?

In­stead of send­ing a world­wide dis­tress alert via the GMDSS satel­lite con­stel­la­tion like an EPIRB or PLB, an AIS SART is sim­ply an AIS trans­mit­ter that sends out an MOB alert mes­sage on the stan­dard AIS VHF fre­quen­cies (161.975/162.025MHZ). This will be dis­played by any Class-a or Class-b AIS re­ceiver within range, usu­ally as an X in­side a cir­cle. Owing to the prox­im­ity of the SART’S an­tenna to the water, in an MOB sit­u­a­tion, its range will be around 4-6nm, less than the 8-24nm ex­pected from a ship’s AIS transpon­der. An AIS SART does not need to be reg­is­tered to the owner or a ves­sel but does come with its own unique MMSI num­ber pro­grammed in so that the res­cue ser­vices can iden­tify it more eas­ily.

Some AIS SARTS also in­clude a DSC func­tion that will send out an MOB Dis­tress Alert mes­sage to your ra­dio (pro­vided you’ve pro­grammed in the MMSI of your boat’s DSC/VHF ra­dio). With some SARTS, this is done si­mul­ta­ne­ously with the AIS trans­mis­sion. Oth­ers send the DSC mes­sage ini­tially, only fol­low­ing on with an AIS alert if it isn’t can­celled within a cer­tain time pe­riod. This handy func­tion al­lows the crew to res­cue the MOB and can­cel the alert be­fore all nearby Ais-car­ry­ing ves­sels re­ceive an MOB alert mes­sage.

HOW WE TESTED THEM

We took six of the most pop­u­lar AIS SARTS into the So­lent on a quiet week­day to try them out. Clearly we couldn’t ac­ti­vate them fully with­out caus­ing may­hem in the busy So­lent but, with the full knowl­edge and per­mis­sion of the lo­cal Coast­guard, we were able to put each one through its full test pro­ce­dure to see if they func­tioned prop­erly and to see if we could re­ceive the ‘Test’ AIS mes­sage on our Garmin AIS re­ceiver and mul­ti­func­tion dis­play.

We also as­sessed how easy they would be to arm and ac­ti­vate man­u­ally, as even the sim­plest pro­ce­dure can be­come a chal­lenge when you’re cold, wet and fright­ened.

All the AIS SARTS had a test func­tion al­low­ing us to see how they worked

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