lw395
Well-Known Member
Fundamentally, you need to decide whether you are in the game of actually going to sea out of comms range or not.
If you don't want to be out of range ever, we have some little lakes with pedalos.
Radio range
- Thread starter The Professional
- Start date
If you don't want to be out of range ever, we have some little lakes with pedalos.
elton
Well-Known Member
It's not only line of sight range you have to worry about. When my boat went down at the foot of high cliffs. I was well within normal transmission range to the marina, but my signal was blocked by high cliffs and outcrops. I was only saved because drilling rigs, well out to sea, picked up my signal, and relayed it to the coastguard. Make sure your antenna is as high as possible (top of mast), and although I've often argued against relying on mobile phones, there's always a chance you'll get a signal, enabling a call to 999.
st599
Well-Known Member
Only if the transmit power and sensitivity of the receiver are the same.
Bilgediver
Well-Known Member
No this is not correct under normal conditions and you should consider yourself lucky to get 20 miles range as an extreme and maybe only 10 miles yacht to yacht. There are exceptions but do not count on these conditions being around when you need them. I can hear Rogoland radio in Norway from my home in Edinburgh on occasion . This is with the help of a couple of factors. Rogoland mast is at a height of 3000ft and I live at 750 ft . However it is not until certain atmospheric conditions develope in the summer that Rogoland and other marine and ham VHF stations can beard.
As others have said VHF is more or less a line of sight transmission so two VHF stations on the peaks of two mountains may reach hundreds of miles . Some coastguard transmitters are mounted on TV masts so this can extend the range. However be aware that many coastguard stations operate through a number of linked transmitters which means that you can be many miles from the actual station but working it through a repeater close to you. This also means you may hear the coastguard working a vessel but not hear the vessel which could be hundreds of miles away.
When on longer passages there are various options with differing advantages and disadvantages.
1. Satcoms. This can either be the low level system Iridium where it operates in a similar manner to a mobile phone but more expensive. Iridium can also be used as a link for various email systems but it is a slow data system to no good for web browsing .
2. Satcoms Inmarsat etc. There are various systems but expensive and can provide data plus voice
3 HF radio. This is a relatively low cost method of long distance communication and there are two distinct methods of achieving this each with their own rules.
3A.
Ham Radio . This requires a ham radio installation and the appropriate operators licence . There are various Radio Nets and other systems around the world which can be used for voice and email when at sea by using short wave radio also if in some coastal waters there is also a VHF. Ham to Ham system that covers the world .
3B.
Marine SSB Radio. This requires a marine SSB radio installation which needs to be added to your Ofcom Radio licence for the boat and you require to obtain the necessary licence. This can be used for ship to ship and ship to shore communications however there are now very few Iynternational Shore SSB Stations any more . However some UK Coastguard Stations still monitor MF 2182 which gives a range of hundreds of miles depending on conditions. Not many ships now carry HF and MF SSB Radio as they can comply with regulations using satcoms redundancy. This means that a GMDSS Mayday call could be a bit of hit or miss though the hit could be with a vessel thousands of miles away. You have to understand propagation in order to make the most of SSB Radio
I have on occasion utilised the help of a ship or an oil rig in order to make contact with family ashore where the communication at sea was VHF with the link vessel and onward communicating by satphone . Just need the cooperation of some one and pick a time at night when the operator might have time on his hands. I would certainly use this method if needing to communicate with family back home from a mid ocean location as all ships have dial tone so just have to sweet talk someone on board. I find that making initial contact in the wee small hours works best but if a vessel comes storming past in daylight then try anyway . A IS will give you the call sign and MMSI number so that either a voice call or GMDSS ship to ship call be made using VHF.
vas
Well-Known Member
fwiw (not much) over winter I had just refitted my LOCATA NAVTEX and from it's dedicated antenna (don't remember exact band but iirc close to vhf) I picked up messages from Italy, Crete and Istanbul which is 300nm way from me. That's on a mobo with the antenna 4m from sea level.
Good weather, will get just the "local" one at 80nm or so (behind a big mountain) and that not always it seems
Good weather, will get just the "local" one at 80nm or so (behind a big mountain) and that not always it seems
lw395
Well-Known Member
Navtex is close to 500kHz. Not VHF.
PilotWolf
Well-Known Member
VHF is traditionally considered line of sight but I have had conversations in marine channels of well over 200 miles.
Radio is a strange medium
Ask any ham operator!
W.
Radio is a strange medium
Ask any ham operator!W.
vas
Well-Known Member
sorry, you're ofcourse right, I stupidly confused that with AIS out of which I'm not getting any great distance..
differentroads
Well-Known Member
What do you want from communications 60km+ from land?
Is it communicate with coastguard in an emergency? An EPIRB is your answer. Possibly with a satphone for conversation. Marine SSB is a poor third option (the vagaries of radio propogation make it unreliable in emergencies and you can't chuck it into the liferaft).
Is it to keep in touch with family? A satphone is your only option.
Is it to receive weather forecasts when offshore? Satphone again (or just stand to your judgement, luck and preperations for bad weather).
Is it just to chat with other people while at sea ? Ham radio SSB or possibly marine SSB. But you'll spend time learning and then fiddling with the technology. And theres not that much chat going on out there.
If you want a comfort blanket of being within 2 way radio range while offshore, sail within 20 miles of shipping lanes. Its surprisingly hard to do otherwise until you get into crossing oceans or sailing to very remote places. Even crossing Biscay 2 years ago, as far as 500km from land, I was never more than 30 or 40km from the nearest ship. Have a look at the Marine Traffic website, particularly their traffic density section.
More important than any of this, make sure that your self confidence and self reliance are such that you don't feel the need to be in contact with other people while offshore except in the most dire circumstances.
Is it communicate with coastguard in an emergency? An EPIRB is your answer. Possibly with a satphone for conversation. Marine SSB is a poor third option (the vagaries of radio propogation make it unreliable in emergencies and you can't chuck it into the liferaft).
Is it to keep in touch with family? A satphone is your only option.
Is it to receive weather forecasts when offshore? Satphone again (or just stand to your judgement, luck and preperations for bad weather).
Is it just to chat with other people while at sea ? Ham radio SSB or possibly marine SSB. But you'll spend time learning and then fiddling with the technology. And theres not that much chat going on out there.
If you want a comfort blanket of being within 2 way radio range while offshore, sail within 20 miles of shipping lanes. Its surprisingly hard to do otherwise until you get into crossing oceans or sailing to very remote places. Even crossing Biscay 2 years ago, as far as 500km from land, I was never more than 30 or 40km from the nearest ship. Have a look at the Marine Traffic website, particularly their traffic density section.
More important than any of this, make sure that your self confidence and self reliance are such that you don't feel the need to be in contact with other people while offshore except in the most dire circumstances.
rotrax
Well-Known Member
After some research we purchased the - at the time - latest floating handheld Icom at a SIBS.
The unit is superb, the unit rarely requires charging and is tested once or twice every season. Last time we were returning from Weymouth heading for Poole Harbour. I called up the NCI at Swanage on the handheld from 5 NM's away, and on the wrong side of Old Harry. Got a response, not good at 4 NM's, conversation at 3 NM'S. NCI at Gosport have answered me from Cowes entrance.
All in all, for a portable pocket bit of kit, well happy.
PS - For those interested, I only test/check our comms with marina's and the NCI, I like to think the NCI volunteers enjoy the contact and a moment to chat. Being based in the Solent at the start and finish of most sailing seasons I am embarrassed at the amount of CG " Radio Check Please " requests my fellow yachtsmen make. Often it is the same yachts, week after week, making the same request.
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Salty John
Well-Known Member
It's best to view radio range as the combination of your radio horizon and that of the station you're communicating with. Your radio horizon is a circle around your boat equal to 1.4 x square root of height in feet, answer is nautical miles. Thus, 49' mast height = 1.4 x 7 = 9.8nm. To this you add "his" radio horizon. If that was also a 49' mast your range would be 19.6nm. The radio horizon of a coastguard station would be very large, as could that of a big ship. So, 60 or 70 mile range is possible, but depends on the other radio horizon.
The only thing you can control is your own radio horizon by having good, fully functional radio and antenna systems, with the antenna located as high as possible.
You can't control atmospheric conditions, of course, and these can lead to increased range, but not predictably.
The only thing you can control is your own radio horizon by having good, fully functional radio and antenna systems, with the antenna located as high as possible.
You can't control atmospheric conditions, of course, and these can lead to increased range, but not predictably.
run_sk
New Member
I am plagued by the complete opposite. My setup is too sensitive. All along the south coast of England I get Cherbourg and sometimes Guernsey on 16 and also find frequent interruptions from distant marinas on 80 when trying to organise a berth.
Speaking to local friends they are not similarly afflicted.
it may be because the cable inside the boat is a fat, commercial grade one, joining the normal vhf at the mast.
Am now trying to find some form of signal reduction.
Speaking to local friends they are not similarly afflicted.
it may be because the cable inside the boat is a fat, commercial grade one, joining the normal vhf at the mast.
Am now trying to find some form of signal reduction.
jbweston
Well-Known Member
Others may well know better than me, but I don't think signal reduction is going to solve the problem. It's unlikely that it's the power of the signal that's causing the difficulty, but the height of your antenna, and of the transmitting antennas. In the Solent and central channel area you have got a bus load of marinas and boats in the 40-60 mile circle around you, many of them chattering away like parakeets.
If you do something to reduce signal strength, unless it's switchable, you're throwing out your emergency baby with the Sunday afternoon bathwater.
You could just turn the thing off until you need it, although I appreciate we all should be keeping a listening watch on ch 16 while at sea. But in crowded waters near the coast why not leave that to the hundreds of other listening stations, including the coastguard and commercial vessels.
I find it refreshing that even in quite busy areas of the Baltic, Kattetgat and Skagerrak sometimes I can go an hour or more with my VHF on ch 16 and only hear one or two calls. Danish, Finnish and Swedish yachts seem only to use the VHF to call port control, for bridge opening or in an emergency.
TernVI
Well-Known Member
I suspect this might be an antenna problem.
If the antenna is mounted wrongly, you can get an effect where it is 'blind' in certain directions but is strongly directed towards e.g. reflected signals from the sky.
Possibly the earthing of the coax outer to the mast is faulty.
Or the AGC in your radio is broken.
Normally the strong local signal should cause the radio to completely ignore the weak distant signal. Could be the local signal is much weaker than it should be.
Does the radio have any RSSI (receive signal strength indicataion) perhaps accessible via a menu sequence?
Can the distant station hear you?
What happens if you turn up the squelch to lose the distant station?
For the normal user, the easiest tests are trying different transceivers and aerials.
You could try a 3dB attenuator between the cable sections, but it needs to be rated to 25Watts and > 170MHz.And obviously compatible with the connectors you have. But it's a band aid not a cure.
And check the thing isn't on 'Dual Watch', that's not an original mistake.....
Uricanejack
Well-Known Member
I haven’t wandered out of sight of land or VHF earshot in several decades with no plans to any time soon. So I haven’t being paying attention.
Somewhere at the back of a drawer or cupboard I do actually have a Radiotelephony licence From the GPO.
Does the GPO still exist?
My DOT certificate is in the same drawer, DOT doesn’t exist anymore.
I was under the impression, No body is listening many more, Portishead Radio and the rest of the shore stations having closed down years ago.
The requirement to carry no longer force. Superseded by GMDSS.
Somewhere at the back of a drawer or cupboard I do actually have a Radiotelephony licence From the GPO.
Does the GPO still exist?
My DOT certificate is in the same drawer, DOT doesn’t exist anymore.
I was under the impression, No body is listening many more, Portishead Radio and the rest of the shore stations having closed down years ago.
The requirement to carry no longer force. Superseded by GMDSS.
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Plymsea
Member
May I encourage the use of Coastwatch stations for radio checks, especially at a distance to find out what the reliable range of your setup is.
If you have line of sight to an NCI lookout of over 10nm this would be a great way to find out what your kit is capable of, they will happily take your call on VHF Ch65. I often do this first on high power and then switch down to see if they can still get a readable signal on low.
Its a good way to reassure yourself that it is possible to stay in contact at moderate distances offshore, without having to go far.
If you have line of sight to an NCI lookout of over 10nm this would be a great way to find out what your kit is capable of, they will happily take your call on VHF Ch65. I often do this first on high power and then switch down to see if they can still get a readable signal on low.
Its a good way to reassure yourself that it is possible to stay in contact at moderate distances offshore, without having to go far.
zoidberg
Well-Known Member
you could try telephoning them, too. And then telephoning the next one along the coast to inquire about the wind and weather there....
"Its a good way to reassure yourself that it is possible to stay in contact at moderate distances offshore, without having to go far. "
run_sk
New Member
thanks for the pointers. I’ll start exploring my options with them.
[70521]
Well-Known Member
A second vote for NCI and radio, AIS checks, but be aware that their antenna will be at different heights above sea level and the effect that has on their transmitting/receiving distances, e.g. Rame Head at about 70 meters and Exmouth at about 15 meters.
Buck Turgidson
Well-Known Member
It's a funny old world. I recently had cell phone signal 22nm from the closest land.
If you are going off shore I would recommend an EPIRB for the boat and a Garmin in reach for yourself. That's what i use and it covers all the bases except long range voice but who needs that? txt is fine.
If you are going off shore I would recommend an EPIRB for the boat and a Garmin in reach for yourself. That's what i use and it covers all the bases except long range voice but who needs that? txt is fine.
