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Thread: Huge benefit of using an external GPS antenna

  1. #1
    Member HuntKodiak's Avatar
    Join Date
    Feb 2007

    Default Huge benefit of using an external GPS antenna

    Over the years, I've seen questions posted about the feasibility of using a chart plotter inside a boat cabin without using an external antenna. Most posts say the internal antenna will work inside a cabin, and when I installed my first Lowrance HDS-5, I used the internal antenna. It would lock onto satellites and give me a position in a few minutes, and seemed to work well while I was fishing or boating around. However, I ran into problems occasionally when it would lose GPS lock, and sometimes this happened while I was cruising and wanted to verify my position in relation to hazards. The last time this happened was when I was on a longer trip to and from a brown bear hunt in bad seas, and it happened more than once. I didn't like that!

    Well I'm here to tell you that the additional expense of buying and installing and external GPS antenna is well worth it! I recently bought an LGC-4000 for my plotters (I installed a second HDS-5 too), and after installing it and connecting it to my NEMA 2k network, the performance change is dramatic.

    For a comparison under the same conditions:
    With the boat parked on my property, getting a position lock with the internal antenna would normally take many minutes. Some days it would take 5 minutes or more. Now with the external antenna, as soon as either plotter powers up, I sequence through the menus as quickly as possible to the satellite status page, and by the time I get there (maybe 15 seconds), the plotter has already locked onto about 10 satellites! Wicked fast.

    Additionally, if you network the antenna, you CAN run multiple plotters off one antenna. I wasn't sure about this when I first thought about buying an antenna, but after a bit of google searching, I was satisfied it should work. Now I can report from personal experience, it definitely does work.

    I know this will result in a summer of more reliable and accurate chart plotter use, and I feel much more confident that I shouldn't experience a loss of fix at inopportune times. I wish I'd done this when I installed my first chart plotter!

    If you want to save a little money, be patient and watch ebay. That's how I got mine.

    Hope this helps answer any questions out there that some might I did.

  2. #2
    Member Cliffhanger's Avatar
    Join Date
    Apr 2006
    Homer, Alaska, USA


    Good info. Thanks!

  3. #3


    When I installed a HDS-8 Lowrance I went with the LCG-4000 right off the bat. In my research before buying I had read the the external antenna was at least 4 times faster than the internal one. On a drift where the boat is rocking you can actually see the rocking on the screen. Very sensitive setup.

  4. #4
    Member bkmail's Avatar
    Join Date
    Apr 2006
    Palmer, AK.


    Good point, I was thinking my wife wasted money buying one for each boat till I used it. Your right it's instantaneous now.

  5. #5


    I have a very old Garmin (1990's) with the antenna mounted on the side of the roof, well below the dinghy. I also have a new model Raymarine with the antenna mounted high atop the radar on a mast. The Raymarine loses it's fix plenty, the Garmin almost never! WHY???

    *An old-salt suggested to drive in a figure-eight to regain the GPS fix. I've done it and seems to work or it's just that amount of time is what is doing it.

  6. #6
    Charterboat Operator
    Join Date
    Jan 2007
    Anchorage AK.


    just purchased the e90, am sceptical but the dealer insists that the internal antenna will work just fine.
    keeping my old garmin on board just in case, but was having second thoughts on the external antenna.

  7. #7


    You know I want to say it's a C model? I can't remember. It has the buttons along the bottom and up the right side. Isn't the E model the larger one? It does work good, just keep in mind it's a computer and if all it does is lose a signal because of cliffs or clouds...

    **It doesn't seem to loses it's signal when I've been running for awhile and things are warmed up???


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