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Author Topic:   GPS Antenna Location On 17-footer
SpeedBump posted 01-06-2006 11:49 AM ET (US)   Profile for SpeedBump   Send Email to SpeedBump  
I'll be installing a Standard Horizon CP150C GPS Chart Plotter on my Nauset and have a few questions for those with experience with this type of installation.

Where is the preferred location for the antenna?

Boat has rail mounted VHF antenna on Starboard side rail at the stern and original stern light on port side transom.

I do have a Mills Sun Top with steel rails but I do not think that would interfere as it never adversely affected my Garmnin 76s with internal antenna.

I can't mount on top rail of windshield frame as I use a full mooring cover and consol cover that may damage the antenna when snapped tight, or the antenna may damage the covers when pullled tight.

I have been thinking somewhere on the top edge of transom on a low bracket or top of console deck by removing the plastic dome extension that accepts the 1" 14-tpi mounting bracket and flush mounting through the consol top but I would prefer not to drill the mahogany top and have yet another hole.

Is it OK to coil the extra antenna cable in the console? Will it affect GPS receiver performance? Cable is 30-feet long.

If the GPS antenna cable is run through the rigging tunnel can it be run next to the VHF antenna transmission line without one interfering with the other? I recall reading some where here that this may pose problems if the cables are to close to each other.

Suggestions are appreciated.

where2 posted 01-06-2006 12:57 PM ET (US)     Profile for where2  Send Email to where2

Never understood why the factory didn't have an internal antenna option. Under the bimini is not a problem... photos of my 15' Sport...

SpeedBump posted 01-06-2006 01:29 PM ET (US)     Profile for SpeedBump  Send Email to SpeedBump     
Where2 - that looks like a great arrangement, what did you use for the antenna bracket and how is it attached to the unit? Clearly coiling the antenna wire does not affect the function.

ALso, where did you get the dual unit mounting bracket

Jerry Townsend posted 01-06-2006 07:55 PM ET (US)     Profile for Jerry Townsend  Send Email to Jerry Townsend     
Speedbump - I have an 17 Outrage and planned on mounting the antenna of the Standard Horizon 160 or 170 1GPS chartplotter on the windshield frame this spring. I will make a special bracket - semi-circular (1/2 of a 1"dia ss tube) which is clamped (two ss radiator hose) to the center vertical windshield frame member, a 1" dia tube about 5 - 6 inches long welded at a 90 deg angle to the semi-circular piece, and a ss threaded vertical tube/pipe welded to the end of the 5 - 6 inch long section. This last piece is threaded (1" X 14tpi) to accept the antenna. A hole would have to be drilled in the 5 - 6 inch long piece to allow the cable to be fed through. I can e-mail you a sketch of this bracket if desired. I do my own welding - but a welding shop might charge $30 or so to make this thing.

The cable can be coiled up without problems. The cable must not be cut - the 30 foot length cable is effectively a part of the antenna and required for proper operation of the GPS system.

This mounting arrangement allows one to have the top of the antenna at the same elevation as the top member of the windshield frame - which does not put any metal above it which would(could) degrade the performance - yet lets me put on a reasonably tight cover without any problems. Then - the only modications to the boat is the holes in the console required for the cable penetrations. ---- Jerry/Idaho

where2 posted 01-07-2006 11:54 AM ET (US)     Profile for where2  Send Email to where2     
The pipe that the antenna is screwed on to is a piece of sprinkler riser (check your favorite home improvement store). The majority of the riser has been cut away to allow you to access the back side of the pipe. It attaches to the back of the GPS unit using the threaded brass inserts designed for surface mounting the GPS unit on a large boat. Use an additional nut as a spacer and to lock your miniature threaded rod (find a 1" screw of the appropriate diameter & thread pitch and cut the screw head off, instant miniature all-thread). Dress the end of the screw you cut with a file and run a nut completely off the cut end to be sure the threads are straight after cutting.

The double unit mount is a piece of 3/8"-1/2" black Starboard mounted to a "Johnny Ray" quick disconnect mount. Note my discussion on where to find these, and some additional photos toward the bottom of this thread: Having the mount able to swivel is a big plus. Disconnect the wires and depress one button and both pieces of electronics remove for security.

As a point of interest, the antenna only works if you mount it to the left side (the side with the card slot). The shuttle point side (right side) of the unit is emitting too much EMI/RFI to work consistently. It took some time to figure that out. Some times it worked, some times it didn't. It randomly lost all satellites, just completely erratic if you mount the antenna on the shuttle point side. My father and I have been using this unit for four or five years now on various boats. I still love it. (Dad's got a Standard Horizon CP160 now).

jimh posted 01-07-2006 03:54 PM ET (US)     Profile for jimh  Send Email to jimh     
I have a Standard Horizon CP-150 with external antenna. The extra cable may be coiled without affecting the GPS receiver performance.

I would not anticipate a problem if the GPS receiver feed line and the VHF Marine Band transmitter feed line were both run in the rigging tunnel. If your VHF radio installation is properly done, there will be no radiation from the feed line, and it will not affect the GPS receiver feed line nearby. If you do notice interference, inspect your VHF transmitter antenna and feed line.

The only problem with mounting the GPS receiver antenna near the engine is the potential for interference from ignition sparking in the engine. Some outboard engines generate very strong electrical noise interference which could affect your GPS reception. I recommend you mount the antenna temporarily in a particular location and test it, before committing to drilling holes and running the feed line there on a permanent basis.

SpeedBump posted 01-07-2006 08:12 PM ET (US)     Profile for SpeedBump  Send Email to SpeedBump     
Thanks to all for your feedback, it will make the install much easier.

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