Is external GPS antenna needed?

[makushin]

I'm thinking about getting the new Garmin 178C plotter/sounder which comes in either internal or external antenna models.

Has anyone had the need for an external antenna? I would prefer to go with the internal antenna as it requires less wiring.

I get great reception with a handheld in my 16CD but will soon have a 22 CD and am not sure if dash mounted electronics would be obstructed from a view of the sky.

 

[Da Nag]

My experience has been that portable GPS units work fine sitting on the dash - they don't need to have a line of site through the window, the satellite signal works through fiberglass. I never have a problem getting an excellent lock with my 76C sitting in a bean bag mount on the helm dash. Others have reported the internal antenna marine Garmin units work fine as well.

Same can be said for XM satellite radio signals - in fact, I stuck my XM antenna on top of the shelf, and it has zero line of site through a window. Works great.

 

[Sneaks]

I agree with Bill. My GPS plotter has an external antenna but I've mounted it inside on the shelf above the helm. No real difference in lock time. My handheld locks just as fast sitting on the top.

 

[Pat Anderson]

Our backup GPS is a Garmin GPSMAP 76 - it works great with no external antenna. I agree with the other responses, I really think the internal antenna will work just fine through the fiberglass roof...

Has anyone had the need for an external antenna? I would prefer to go with the internal antenna as it requires less wiring.