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
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.