Gps with internal antenna - does it work?

[tmr7s]

I'm looking at a Raymarine A-50 GPS - it had an internal antenna - will it really work in an electronics box under a hardtop? - thanks - tom

 

[bruceb58]

Re: Gps with internal antenna - does it work?

Fiberglass hardtops are fine. It is metal framework that will affect it the most. Most of the newer GPS units are very sensitive these days. For example, most GPS handhelds work fine indoors even....including the GPS in my IPhone.

 

[Boatist]

Re: Gps with internal antenna - does it work?

I agree with Bruce58.
If your have a metal roof then may be a good idea to get a unit with a external antenna. External is slightly better but also seem to have more failures than internal.
Most of the Satellites are very strong and in low earth orbits so easy to pick up. The exception is the WAAS satellites which are in GeoStationary orbits over the equator about 22,000 miles high. So the farther North you go the lower on the horzion they are and the farther away they are and the weaker they are.
The WAAS satellites are use for error correction of the normal GPS birds. With good error correction the gps is good to about 10 feet. Without the error correction it is about 30 feet.
I few year back they added more WAAS birds in the south of the USA and reposition them to have better coverage so pretty easy to pick up now. Still the farther north you go the lower on the horizon they are and the more likely that they will be blocked from view by something on the boat. If your way up north or have a lot of metal or heavy structure that may block the WAAS bird signal and you need 10 accuracy then the extra cost of the external antenna may be worth it. Other wise the internal antenna today work very well.