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Canvas T-Top, GPS Internal Antenna

Old 10-23-2006, 06:25 PM
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Default Canvas T-Top, GPS Internal Antenna

I've seen a few old threads on thsi topic with mostly speculation about WAAS reception- anybody with real world experience, good or bad, using an internal antenna under a canvas ttop?

I'd like a unit that I could use on another small boat once in a while. Does anybody make a unit that has an internal antenna with a jack for an external antenna as well?
Old 10-23-2006, 06:36 PM
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Default Re: Canvas T-Top, GPS Internal Antenna

My fixed Garmin GPSMAP 162 (internal antenna) and handheld Lowrance iFinder H2O GPS units both work very well under my sunbrella T-Top. WAAS reception doesn't seem to be a problem.
Old 10-23-2006, 06:43 PM
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Default Re: Canvas T-Top, GPS Internal Antenna

I have a Lowrance 339i and it goes in and out way to much for my liking. So much I had to turn the alarm off because it was starting to get pretty annoying. However..I'm convinced it has nothing to do with the Top. I have a Garmin 276 that never looses a fix. Fortunately the GPS on the 339 is only for backup purposes. At one point I was able to get a fix through the Top and the boat cover. Having said all that you should be fine.
Old 10-23-2006, 07:01 PM
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Default Re: Canvas T-Top, GPS Internal Antenna

I have a Lowrance Globalmap 3600 with the internal antenna. It is horrible if you have a T-Top, took it out and used it on my friends boat without a top and it works beautiful. Actually looking to sell it and get an external.
Old 10-23-2006, 07:51 PM
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Default Re: Canvas T-Top, GPS Internal Antenna

I have both a Lowrance and a Raymarine external GPS antenna mounted inside the pilot house on my C-Dory, on a shelf. Both work just fine under a 3/8" cored fiberglass roof so I would expect them to work even better under Sunbrella.
Old 10-24-2006, 04:27 PM
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Default Re: Canvas T-Top, GPS Internal Antenna

The Lowrance 3600 and other internal GPS units will all take an external antenna (LGC2000) as part of a simple LowranceNET network as an LGC is a NMEA2000 device. You just need to disable the internal antenna via the menu system.

TT
Old 10-25-2006, 09:27 AM
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Default Re: Canvas T-Top, GPS Internal Antenna

Thanks for the feedback. The internal results sound pretty good, but after further reflection, I'll probably go with a hardwired external antenna so I can place the unit inside the lockable clear console for the main boat, with a no frills handheld for the second boat that can double as emergency back up in boat #1.
Old 10-26-2006, 02:18 AM
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Default Re: Canvas T-Top, GPS Internal Antenna

....with mostly speculation about WAAS reception- anybody with real world experience, good or bad, using an internal antenna under a canvas ttop?
With regards WAAS reception with or without any type of top this is not speculation, it is simply not totally reliable, this is in any world.

One thing you have to understand here here it has nothing to do with the canvas top but the obstruction of signal by the surrounding environment in general and this includes people and especailly in the case of geostationary WAAS signals. The lower the unit is mounted the higher the probability is of reducing performance. There is no one simple answer as all installations, environments are generally different.

If you are prepared to accept a lower integrity as a trade off then you accept this fact by going internal.

Regards, Kerry.
Old 10-26-2006, 06:11 AM
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Default Re: Canvas T-Top, GPS Internal Antenna

I am not strong on this stuff but what about de-selecting 'Require WAAS' in the GPS set up menu. If it is a WAAS issue could you not exchange some accuracy for a more consistent signal.

TT.
Old 10-26-2006, 09:42 AM
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Default Re: Canvas T-Top, GPS Internal Antenna

My LGC2000 is mounted on my console under a hardtop. When doing the initial set-up, I had to disable WAAS (or at least go to the tab that says "require WAAS" and uncheck that.) It works ok now. I use it as a backup. Sometimes the WAAS signal acquires, sometimes not. But it always works.

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