VHF distance

fishwhenican · 05-11-2003, 07:17 PM

I recently installed a new Icom M402s VHF and a Shakspere Galaxy 8' antenna. I understood that a VHF would likely only transmit and receive up to apprx 25 miles depending on height of sending antenna.

Fishing from Port Orford for Halibut I received USCG transmissions from the Umpqua station and the Chetco station, both apprx 50-55 miles from my location. The Umpqua station was an answer to a bar report question so I'm sure it wasn't relayed from Coos Bay or anywhere closer. The Chetco was a Mayday help request, which may have been relayed up the coast to Gold Beach? If I can receive these transmissions, would they be able to hear me at 35 miles out at 25 watts, or does the Coast Guard exceed the max watts? The answer may make me feel better about someone hearing me when I am out after TUNA.

Lepper · 05-11-2003, 08:35 PM

I don't know about the watts ect... But I do know that conditions outside have a lot to do on radio waves.. Solar flares ect... If the skip is right you could technically talk a heck of a long ways away...

Pilar · 05-11-2003, 08:49 PM

Lepper, VHF is line of sight. That means that you typically cannot transmit to or recieve from any station more than about 15 miles away. Power is somewhat irrelevant, even 5 watts can go that far.

The CG put their antennas on high points along the coast. This extends the apparent horizon to 50 + miles. The phenomena of 'Horizon' results is such strange things as you can hear the CG talking to someone but you can't hear the someone. The CG is farther away but you can hear them and not the boat that is closer. Your antenna can 'see' the CG antenna that is hundreds of feet above sea level but not the boat antenna that is 10 feet above sea level.

If you mayday on a TUNA! trip they will most likely hear you. But the distance will make the response time pretty long.

Rely on friends and run in wolf packs for best results.