[70521]
Well-Known Member
Interesting, we often hear Guernsey CG on the Exe and Falmouth CG in Roscoff. Quite sure they can't hear us
Handheld vhf: range when transmitting from water level
- Thread starter JimC
- Start date
fisherman
Well-Known Member
Interesting, we often hear Guernsey CG on the Exe and Falmouth CG in Roscoff. Quite sure they can't hear us
I have heard Dover CG in Helford, high pressure conditions, and I regularly hear Ushant via a slimjim on an icom handheld, but these are good aerials and high up.
Eygthene
Well-Known Member
Quite apart from the matter of line of sight, surely signal strength would come into the transmission range of a handheld. Mine has 1 watt on low power and 5 watts on high power, compared to the fixed VHF with 25watts maximum. The OP was enquiring about range in relation to its use as a means of calling for help from water level.
bedouin
Well-Known Member
Theoretically it doesn't make that much difference - range is proportional to the square root of power so if 25W has a range of 20miles say, 5W would have a range of 14 miles (it is not quite that simple as antenna design is also involved).
That said I am not sure how many 5W hand helds can actually transmit at 5W - that must place a large demand on the battery
lpdsn
Well-Known Member
I gave up using the HH to contact Belfast VTS from beacon No. 12. It worked more often then it didn't, but it didn't more often than I liked.
On the other hand, a few years ago I did pick up a HH VHF transmission from a survivor in the water in the W Solent, as did the coastguard, another yacht, a coaster, both Yarmouth-Lymington ferries and the Yarmouth water taxi.
On the other hand, a few years ago I did pick up a HH VHF transmission from a survivor in the water in the W Solent, as did the coastguard, another yacht, a coaster, both Yarmouth-Lymington ferries and the Yarmouth water taxi.
Daydream believer
Well-Known Member
Cg aberdeen picked me up in an emergency situation at about 30 miles
They asked me to go from 16 to 67 but then could not get me so we went back to 16
I was laying on cockpit floor so height about 600mm for my hand held
Lifeboat could not get me at 10 miles so cg relayed messages.
Cg aerial must have been very high
They asked me to go from 16 to 67 but then could not get me so we went back to 16
I was laying on cockpit floor so height about 600mm for my hand held
Lifeboat could not get me at 10 miles so cg relayed messages.
Cg aerial must have been very high
chrishelen
N/A
I sometimes get a coastguard station over 40 miles away on my hh, depends on weather conditions I believe.
rbmatthews
Well-Known Member
As noted in #14, it is not so much the distance to the CG station itself that matters, but the distance to its nearest transmitter.
For example, this year we could pick up Stornoway CG loud and clear with our HH (a SH HX851e) on the south side of Soay Island, a distance of 65NM to Stornoway as the crow flies with the Cuillin mountains in between, so not much line of sight, but their nearest transmitter was in Arisaig, just 17 NM away. That's what we were hearing. Earlier, we could both send and receive perfectly to them with the HH when we were just off the Ascrib Islands, a distance of about 16 NM to the transmitter at Rodel.
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chrishelen
N/A
That would explain it then... Thanks.
JimC
Well-Known Member
OK, but (in the context of my original question) can one rely on achieving this sort of range in an emergency situation especially from water level. General consensus seems to be no - get a PLB.
maby
Well-Known Member
Never assume any better than line of sight. At VHF frequencies, you can get unusual propagation conditions - usually linked to weather - which can result in vastly increased range, but they are unpredictable and infrequent and certainly should not be relied upon to save your life! I'm a radio amateur and sometimes carry a 5w SSB hand-held with multi-band coverage. Some years ago, I was on holiday in SW France, near Bordeaux, and had a chat with a group of radio amateurs camped on the island of Rockall. By my reckoning, that was a range of over 1000 miles done with 5w into a rubber duck antenna while I was standing on the beach... I certainly would not want to rely on it to summon assistance, though!
rbmatthews
Well-Known Member
In our case, the antenna was probably about 2m above sea level in each case - the first in very smooth conditions, the latter in somewhat choppy conditions described as moderate. Both transmitters would have been more-or-less line-of-sight, even if the CG station wasn't. We established contact with the CG using DSC (they volunteered to help us do checks on both our radios), but even so, the subsequent voice transmission quality was still pretty good. In an emergency though, the DSC does seem to have a greater range and reliability than voice transmission - the CG themselves told us that - and it has the advantage that it sends your position automatically.
I wasn't really advocating relying on the HH in such a situation, just making the point that the distance to the CG station itself is not as relevant as the distance to its nearest transmitter. I would agree that it is not advisable to rely on the HH only in an emergency situation - things never work just when you need them!
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rbmatthews
Well-Known Member
I wouldn't either - it would take a while for it to arrive from Rockall! Better to find the beach lifeguard.
jac
Well-Known Member
THink that needs to be tempered by WHERE & WHEN you sail.
we are Solent based - our range is bordered by West country and Channel Islands. Work full time so apart from 2 weeks in August we sail at weekend. WHat that means is that even crossing from say Studland to Guernsey or across Lyme Bay there are highly likely to be multiple other vessels within a realistic range of the HH DSC even if we are temporarily outside the range of Solent / Portland / Brixham CG or CROSS Jobourg
Sailing somewhere more remote where there are not busy shipping lanes or other yachts on fairly standard passages then the contingency of a HH DSC reaching another vessel may not be realistic so a PLB / EPIRB would move up the priority list
Twister_Ken
Well-Known Member
The way I read the OP, the query was what's the range of a h/h VHF when you're in the water. If it's twice bugger-all, which is my expectation, then it's not going to get you rescued in you fall in somewhere off the South Coast, whereas a PLB will, sooner or later.
maby
Well-Known Member
PLBs are so cheap these days that they really should be considered standard safety items. My wife and I each have one - and we do not limit them to the boat - if we were out hill walking, we would be carrying one - I'm reaching that age where a heart attack is an increasing risk - I would have no hesitation setting off the PLB if I were feeling seriously ill and away from rapid help. My wife was travelling in the remote parts of northern Canada last year on roads that often see one car per day - again the PLB was an important item.
jac
Well-Known Member
True for MOB. Personally I suspect that if the boat you were on doesn't see you & raise alarm / rescue then you're dead anyway - maybe with the exception of the solent in a sunny summer Saturday. I was thinking more of the scenario of abandoning ship and being able to trigger the DSC Mayday whilst in a liferaft or whilst still on the yacht.
Key point though was that it is all about the risk and that other closer boats can reduce the risk of not being heard but do of course add other risks
maby
Well-Known Member
With a good lifejacket and decent oilies, you can stay alive in the water for several hours unless it is very cold - plenty of time for a PLB to summon help provided you are within helicopter range.