Draw a straight line from deck level and one from the top of the mast. Assuming a 20º angle, go out about 5 miles and see how much higher the mast line is over the deck line. This is using comparable gain antennas. Now, this may seem counter intuitive, but the broader angle of radiation from the low gain antenna on the mast will still reach the horizon, while the high gain antenna will just go out into space. Remember, line of sight, not power is king.
~Rich
Where to mount VHF
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Russ
- Admiral
- Posts: 8320
- Joined: Thu Oct 11, 2007 12:01 pm
- Sailboat: MacGregor 26M
- Location: Bozeman, Montana "Luna Azul" 2008 M 70hp Suzi
Re: Where to mount VHF
Take a walk down the dock at your marina and look up at masts, then look at the decks of sailboats. How many have mast mounted VHF and how many are at deck level? Ask yourself why this is so.
Speed of rigging is certainly a valid reason for deck mounting. But a deck mounted antenna is also a liability, another pole in the way.
This is a topic we have discussed ad nauseam in other threads. I will simply ask why do you have a VHF radio aboard? For me, it is the single, cheapest piece of safety equipment on board. If I need help, I want to communicate with those who can help. For me, saving 2 minutes of rigging time is not worth the loss of added range I get with a mast top antenna.
The times I've been out and believed we might be in trouble and need help were the times the wind and waves were wild. The boat was bouncing around and a high gain antenna would probably be shooting my signal at the sea or ISS.
I own a handheld that I use for short range communication and it works very well. But if I needed to reach someone 20 miles away, I'm going for my 25w VHF and mast antenna.
Now if I ran mast down, deck mounting would be the only decent option. Having a deck mount as backup (or any backup) isn't a bad idea either.
For me, I'm enjoying the altitude advantage of a mast antenna that my powerboat neighbors envy.
--Russ
Speed of rigging is certainly a valid reason for deck mounting. But a deck mounted antenna is also a liability, another pole in the way.
This is a topic we have discussed ad nauseam in other threads. I will simply ask why do you have a VHF radio aboard? For me, it is the single, cheapest piece of safety equipment on board. If I need help, I want to communicate with those who can help. For me, saving 2 minutes of rigging time is not worth the loss of added range I get with a mast top antenna.
The times I've been out and believed we might be in trouble and need help were the times the wind and waves were wild. The boat was bouncing around and a high gain antenna would probably be shooting my signal at the sea or ISS.
I own a handheld that I use for short range communication and it works very well. But if I needed to reach someone 20 miles away, I'm going for my 25w VHF and mast antenna.
Now if I ran mast down, deck mounting would be the only decent option. Having a deck mount as backup (or any backup) isn't a bad idea either.
For me, I'm enjoying the altitude advantage of a mast antenna that my powerboat neighbors envy.
--Russ
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Catigale
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Re: Where to mount VHF
I tried to reach the ISS but they sent me back a message saying I was very faint.
They said "Call me ISS Ham yell."
They said "Call me ISS Ham yell."
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mastreb
- Admiral
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- Location: Cardiff by the Sea, CA ETEC-60 "Luna Sea"
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Re: Where to mount VHF
In the end I decided to mount the VHF here:
This lets me grab the mike from the cockpit, it's very obvious to all where it is, and the cable runs are all a piece of cake. I did have to rotate the cabin light 90 degrees. I wanted a position where the VHF would not block its light.
I've got power, coax, and NMEA-2000 going along the liner to the stern, where he coax goes out the cable through-way to the antenna on the mast bracket. Power goes under the aft berth to my switch, and NMEA-2000 goes to my backbone segment in the battery box.
The VHF works very well. It picks up AIS tracks all over the place which automatically display on the chartplotter, and has alerted me to possible collisions every time I pull into a marina, as it picks up the 4 or 5 vessels transmitting dockside.
It also takes its GPS source from the chartplotter so automated distress calls go out with my position, no extra GPS involved. It did take me a bit to find the configuration option to use the chartplotter GPS. Now all I have to do is get an MMSI and get it programmed, but the Boatus website doesn't work on an iPad and I'm underway right now.
Very happy with this RS-35 unit.
This lets me grab the mike from the cockpit, it's very obvious to all where it is, and the cable runs are all a piece of cake. I did have to rotate the cabin light 90 degrees. I wanted a position where the VHF would not block its light.
I've got power, coax, and NMEA-2000 going along the liner to the stern, where he coax goes out the cable through-way to the antenna on the mast bracket. Power goes under the aft berth to my switch, and NMEA-2000 goes to my backbone segment in the battery box.
The VHF works very well. It picks up AIS tracks all over the place which automatically display on the chartplotter, and has alerted me to possible collisions every time I pull into a marina, as it picks up the 4 or 5 vessels transmitting dockside.
It also takes its GPS source from the chartplotter so automated distress calls go out with my position, no extra GPS involved. It did take me a bit to find the configuration option to use the chartplotter GPS. Now all I have to do is get an MMSI and get it programmed, but the Boatus website doesn't work on an iPad and I'm underway right now.
Very happy with this RS-35 unit.