That's a lot of acronyms. VHF and GPS we all know about, but DSC is the new coastguard emergency protocol here in the US. When correctly set up, DSC allows an automatic emergency call on a dedicated frequency, which provides the coasties with boat information and position with the press of a button. In order to meet the local offshore racing requirements, I had to install a 25 watt DSC radio with a masthead antenna for last year's Single Handed Farallones race.
The radio is a Standard Horizon GX1600 and is mounted on a ply pad that I glued to the cabin side. That was the easy part! I chose this model, which is a little more expensive than the base model, because it accepts the RAM 3 powered extension microphone that I have outside in the cockpit when things get wet.
The hard part is installing the VHF antenna. I dropped the mast, and drilled a largish hole at the top and bottom of the mast. I used an electrician's fishing wire, that I bought from the Home Depot for $10, to "fish" the vhf cable through the mast. The cable is marine coaxial and is surprisingly expensive, but has proven reliable in the long term. The coax connectors had to be soldered at each end, so I also have a new soldering iron.
I left some slack coax at the bottom of the mast in case I have to adjust the cable tension, and ran the cable through a simple Sea Dog brand thru-hull into the starboard cabin. I chose not to add a connector at the mast base to maintain a single continuous cable from radio to masthead.
In order for the radio's DSC capability to work properly, it has to receive data from a GPS. I was too, um, economical to buy a vhf with internal gps, so needed to wire in my hand held GPSMAPcx GPS. This required the purchase of the Garmin accessory cable which I bought online for about $20.
Here is how I wired the VHF to the GPS accessory cable:
VHF GPSMAPcx (via the accessory cable)
Blue GPS in + Brown GPS out +
Gray DSC out + White GPS in +
Green (GPS in - ) Black -
Brown (GPS out - ) Black - (connected to both Green and Black)
Red + (power from battery)
The accessory cable comes with a dedicated ground (black) to run back to the battery. But I found that there was sufficient ground through the (green and brown) negative connections on the VHF, and that the dedicated ground was not required (saving an extra run back to the battery).
The GPSMAP is installed on the standard Garmin mount on a pad of ply that I epoxied to the hull side. One of the unforeseen benefits of wiring in the handheld is that it is powered as soon as the accessory cable is plugged in and I am not changing batteries all of the time. Also, the mount position allows me to read the GPS from the cockpit with the hatch cracked open, and it is not out in the elements.
Everything is wired to a U1 battery which seems the right size for the dimensions of the TIKI 21, and that I only charge up every few weeks. It seems to have plenty of reserve for the mild draw of the VHF + GPS. This picture also shows the temporary battery set up. I plan to mount them permanently under the bunk at a later date. A second U1 battery powers the autopilot.
It is now a year after installation and the whole system has proved very reliable with no problems. I can now sail offshore and up and down the coast with improved peace of mind having the extra range of the installed VHF. Estimated range is 20 miles vs just 5 miles with my hand held VHF. The furthest I've called so far is from Point Reyes to SF coastguard (more than 20 NM) and the transmission and reception was crystal clear.
The radio is a Standard Horizon GX1600 and is mounted on a ply pad that I glued to the cabin side. That was the easy part! I chose this model, which is a little more expensive than the base model, because it accepts the RAM 3 powered extension microphone that I have outside in the cockpit when things get wet.
 |
| VHF on cabin side. Note the coax cable through the bulkhead. |
The hard part is installing the VHF antenna. I dropped the mast, and drilled a largish hole at the top and bottom of the mast. I used an electrician's fishing wire, that I bought from the Home Depot for $10, to "fish" the vhf cable through the mast. The cable is marine coaxial and is surprisingly expensive, but has proven reliable in the long term. The coax connectors had to be soldered at each end, so I also have a new soldering iron.
 |
| Standard Shakespeare 3dB sailboat antenna |
 |
| coaxial through hole drilled in bottom of mast |
I left some slack coax at the bottom of the mast in case I have to adjust the cable tension, and ran the cable through a simple Sea Dog brand thru-hull into the starboard cabin. I chose not to add a connector at the mast base to maintain a single continuous cable from radio to masthead.
 |
| Seadog thru-hull |
In order for the radio's DSC capability to work properly, it has to receive data from a GPS. I was too, um, economical to buy a vhf with internal gps, so needed to wire in my hand held GPSMAPcx GPS. This required the purchase of the Garmin accessory cable which I bought online for about $20.
 |
| Garmin accessory cable and GPSMAPcx |
Here is how I wired the VHF to the GPS accessory cable:
VHF GPSMAPcx (via the accessory cable)
Blue GPS in + Brown GPS out +
Gray DSC out + White GPS in +
Green (GPS in - ) Black -
Brown (GPS out - ) Black - (connected to both Green and Black)
Red + (power from battery)
The accessory cable comes with a dedicated ground (black) to run back to the battery. But I found that there was sufficient ground through the (green and brown) negative connections on the VHF, and that the dedicated ground was not required (saving an extra run back to the battery).
The GPSMAP is installed on the standard Garmin mount on a pad of ply that I epoxied to the hull side. One of the unforeseen benefits of wiring in the handheld is that it is powered as soon as the accessory cable is plugged in and I am not changing batteries all of the time. Also, the mount position allows me to read the GPS from the cockpit with the hatch cracked open, and it is not out in the elements.
Everything is wired to a U1 battery which seems the right size for the dimensions of the TIKI 21, and that I only charge up every few weeks. It seems to have plenty of reserve for the mild draw of the VHF + GPS. This picture also shows the temporary battery set up. I plan to mount them permanently under the bunk at a later date. A second U1 battery powers the autopilot.
It is now a year after installation and the whole system has proved very reliable with no problems. I can now sail offshore and up and down the coast with improved peace of mind having the extra range of the installed VHF. Estimated range is 20 miles vs just 5 miles with my hand held VHF. The furthest I've called so far is from Point Reyes to SF coastguard (more than 20 NM) and the transmission and reception was crystal clear.
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