VHF range problems

[Jsmfun]

So I have come to the conclusion that I only have about a 20km range with my VHF garmin radio should this be more as I thought having a VHF would give me around 100km rang.

out from musgrave I could not here any chatter or raise anybody until we got about 20 km from 1770 and she said we were very distorted what would cause this as I fish 45km offshore on my own and if I need help well you get the picture I did get a response about 30km from 1770 on channel 16 but I don't ever want to use this channel unless boat is sinking.

any help would be appreciated
cheers scott

[Noelm]

I guess to start at the beginning, is the equipment new? If not, did it ever work properly? What sort of antenna do you have, any radio is only as good as the antenna, it needs to be as long as possible, and be mounted as high as possible, and be a VHF antenna of course.

[Jsmfun]

Hi noelm yea mate 7 months old and a 1.8m VHF ariel sitting on top of a stainless steel rocket launcher top of ariel is about 4.2m above water level. Don't know what brand ariel sorry

[scottar]

VHF range is regarded as "line of sight". As such a typical range for a trailer boat without using a repeater maxes out at about 20Nm with a standard antenna. There are "high performance" antennas that are available that promote an increase in range (of up to 50%) but their effectiveness apart from the manufacturers claims I am unable to confirm. What Noel has posted about height is correct - the higher the better but there reaches a point where practicality has to win out. The other thing to be careful of in a small boat is using extremely high gain antennas. Due to the pitching/rolling motion of small craft and the compressed radiation pattern of high gain antennas a break up in signal can be experienced.

To provide an increase in range, various bodies have installed repeaters at various locations around the country which are typically mounted in high altitude locations. The way these repeaters work is to effectively re-transmit a received signal on a different frequency. On a repeater channel, even if the boat/VMR you are trying to talk to is only 100 metres away, the signal is still going all the way to the repeater and then all the way back again on the receive frequency. The repeaters are channel specific and your radio must be set to international so as to be using the correct frequencies to work with them properly. If your radio is set to US or Canada, they will not work. VMR Round Hill monitors channel 81 and 82 which are repeater channels

Things to check - Good power supply with no voltage drop when you transmit, Radio is set to high power and International, all connections are clean and tight. From this point forward you will need specialist equipment - RF Power and SWR meters and the knowledge to use them if you wish to fault find further short of simply attempting repair by replacement

[Jsmfun]

Thanks Scott so much more than just turning it on .and picking up vmr.
I will check for power loss .
I though if I was on the 50's of the Gold Coast I should be able to reach the seaway tower but I can not until I get back to the 36's and then it's distorted and patchy . Now I did my first trip to 1770 how do people get in contact with round hill if they need them that far out in a trailer boat as I'm going back in March and want to know I can call somebody in a emergency that does not require a Epirb

cheers scott

[scottar]

I've not fished up that way myself but I would assume people are either using the VHF repeaters or, if they are really safety conscious taking a handheld sat phone. Your radio system certainly doesn't sound like it is as good as it could be. It would probably be worth getting the boat to a marine comms specialist if you wish to fault find. The other option would be to just outlay the dollars and put a second unit in - possibly with a high performance antenna. A couple of other things I forgot - do you have a splitter in the system for AM/FM - if you do - get rid of it. Also, next time you are on the water and try to call someone, shut down your engine and all the other electronic items (GPS/sounders etc) just to make sure you don't have an interference issue.

[myusernam]

higher gain antenna wont do dick - you are limited by curvature of earth. two line of sights at sea level plus a bit isn't far. but the coast guard will have an elevated antenna. Go to coast guard and see what sort of range you should reliably get at your local areas. then try them from there. also get repeater info as this will increase your range greatly. that said most problems are power. voltage drop - poor cabling. Bare the wires at the radio. put a voltmeter across it. transmit and talk into it. make sure you are still getting over twelve volts.

[QF3 MROCP]

Not interested if you haven't the MROCVP to operate it, but go to one of the courses run by Coast Guard or VMR and learn about the operational aspects of VHF Marine radio.

What has been said by scottar is spot on. Never have a fear about using channel 16 to make contact with anyone in the area. 16 is a calling and distress channel. All commercial vessels should be maintaining a practical listing watch on 16. Crusie Shps, military, trawler boats, commercial charter, so the coverage for 16 is not just land based.

Just a note to everyone else... if you are going into a new area off the coast, check with the locals first about the radio coverage. There is a wide spectrum of channels used that may not be published. Also the comment about the international setting has caught people out over time. If you have USA / Int setting, make sure it is on Int for Australia and give a working channel 73 call to a land based station eg VMR just to make sure it is correct.

As a footnote, the assigned frequency which you don't need to remember, is programmed into the radio's channel settings at the place of manufacture. This problem occurs a lot when buying marine radios from overseas.

Finally, never assume every land based VMR (Volunteer Marine RADIO) is 24x7x365 operational. Check with the locals again for their respective operational times as they all different around the country.

[QF3 MROCP]

Thanks Scott so much more than just turning it on .and picking up vmr.
I will check for power loss .
I though if I was on the 50's of the Gold Coast I should be able to reach the seaway tower but I can not until I get back to the 36's and then it's distorted and patchy . Now I did my first trip to 1770 how do people get in contact with round hill if they need them that far out in a trailer boat as I'm going back in March and want to know I can call somebody in a emergency that does not require a Epirb

cheers scott

Scott.. If you believe you have an emergency i.e. "the vessel is in grave and imminent danger", activate the EPIRB if you are out far as you may not have time to muck around getting out a MAYDAY Call... speaking of which, have you practiced one or your crew know how to use the radio?

Send me a PM and I'll get you some more info...

[Jsmfun]

so it works i have called my local vmr on channel 73 many times to log on/off and I knew round hill vmr was on 81 and 82 we logged on by phone and called them on the radio as we were setting of to musgrave.
i picked them up coming back in when i got 20km from land i did not know i had a problem my decki thought it was strange as he works on boats of the GC every day around the 50f line and can reach the seaway tower i might do a course though

[tropicrows]

Weather plays a big part. I have found if you are down wind you can here others but they can't here you. We often get better mobile phone coverage offshore than with VHF.

[QF3 MROCP]

so it works i have called my local vmr on channel 73 many times to log on/off and I knew round hill vmr was on 81 and 82 we logged on by phone and called them on the radio as we were setting of to musgrave.
i picked them up coming back in when i got 20km from land i did not know i had a problem my decki thought it was strange as he works on boats of the GC every day around the 50f line and can reach the seaway tower i might do a course though

You may find it is also the power output of the respective VMR's transmission and height / location of their antennas. The higher both receiving and sending antennas are the greater the "direct line of sight" coverage.

Check out this link to the VHF Handbook... https://www.amc.edu.au/handbooks

Ausfish VHF Range.JPG

P.S. Disclosure: I promote the sale of the handbook at www.vhfradiocourse.com

[Jsmfun]

thanks very much for all the info. i have got some reading to do by the looks of that.


thank you guys for the assistance

[Assasin]

Hi Jsmfun
I fish this area regularly and find that this area can be a bit of a black hole. I fish also off Moreton Is and have no problems talking on 21 to the sunshine coast and Noosa and to the GC on 73 but up at Musgrave we have Dramas. Have spoken to alot of guys that have the same issue.

Assasin

[honda900]

Round hill in particular has issues with their radio range, even in the creek there are certain places it will not work.

REgards
Honda.