Emer­gency VHF an­ten­nas

In a dis­mast­ing, you’d want to be able to rely upon an emer­gency VHF an­tenna to main­tain ra­dio con­tact. Alex Bell and a PBO test team put five ex­am­ples to the test

Practical Boat Owner - - Contents -

Which one de­liv­ers the strong­est and clear­est sig­nal?

Dis­mast­ing is one night­mare sce­nario all sail boaters have to be pre­pared for. Over the years I have been sail­ing, I’ve ex­pe­ri­enced a few such sit­u­a­tions; two were in my dinghy days, close to shore, no big deal. Two more were with keel­boats: the first was a spreader fail­ure on a quar­ter ton­ner, re­sult­ing in the mast break­ing at the spreader, while the sec­ond was after be­ing T-boned at the start of a race – the whole rig came down.

In both cases my main VHF ra­dio was ren­dered use­less, but in the sec­ond in­ci­dent we made ra­dio con­tact with a hand­held and were able to com­mu­ni­cate with the start boat. They re­quested an air­lift for an in­jured crew­man. The prob­lem with hand­held ra­dios is, of course, their range. With, typ­i­cally, 5W max­i­mum trans­mis­sion power and an an­tenna fixed to the set, range is lim­ited – de­pend­ing upon the at­mo­spheric con­di­tions – to around 4 miles.

This is where an emer­gency an­tenna comes in use­ful. Firstly, it can be con­nected to your main ra­dio and de­liver 25W of power: se­condly, there is the po­ten­tial to raise the aerial as high as

pos­si­ble to ex­tend its range should help be needed. For this rea­son emer­gency VHF an­ten­nas are re­quired un­der ISAF Off­shore Special Reg­u­la­tions for cer­tain safety cat­e­gories (0,1, 2, 3) for off­shore yacht rac­ing, when the reg­u­lar an­tenna de­pends upon the mast. Un­der race con­di­tions it would be rea­son­able to ex­pect that other com­peti­tors may be close enough for ra­dio con­tact, ei­ther from a hand­held ra­dio or us­ing the main set with an emer­gency an­tenna and thus able to ren­der as­sis­tance.

Avail­able for the UK mar­ket are five makes of emer­gency VHF an­tenna: Ban­ten, Glomex, Pa­cific, Shakespeare and VTronix. We also de­cided to in­clude an AIS an­tenna which would more typ­i­cally be at­tached to the push­pit and hence sur­vive the loss of the main mast an­tenna.

How we tested them

We used our stan­dard test for VHF ra­dios and an­ten­nas, be they main sets or hand­held. We placed one boat, a Beneteau First 305 (Sym­phony), on a moor­ing buoy off Cal­shot in Southamp­ton Wa­ter and our sec­ond boat, a Nel­son 42 (Trin­ity Star), ‘steamed’ in a south-east­erly di­rec­tion, stop­ping at reg­u­lar dis­tances to test the an­tenna’s range.

One prac­ti­cal as­pect of de­ploy­ing an emer­gency an­tenna with your main ra­dio is ac­cess to the an­tenna con­nec­tion at the rear. Ideally it should be eas­ily ac­ces­si­ble, with­out hav­ing to re­move the ra­dio from its lo­ca­tion at the nav­i­ga­tion sta­tion.

The Beneteau First 305 has an air draught of 12.6m: on the Nel­son, the emer­gency an­ten­nas were at­tached at a height of 2.5m.

Sym­phony in Southamp­ton Wa­ter

Newspapers in English

Newspapers from UK

© PressReader. All rights reserved.