Humminbird gps998c si

[brantley moats]

I would like to know if there is is any gps (waypoint) accuracy increase or reduction between a 998C SI bought last year with external antennea and a new (same model) Humminbird with the internal antennea?
Thanks,
Brantley

 

[AirForce]

depending on the external antenna, but external if placed correctly can give better results. Read this for more info on dual band and differential GPS http://water.usgs.gov/osw/gps/

 

[brantley moats]

LoL, way to technical for me. I guess my question should have been more specific I.E. would an external antennea be better for finding a specific spot on or under water as opposed to an internal antennea??
Thanks,
Brantley

 

[AirForce]

again, it depends on the antenna, generally yes but lots of conditions apply, so can't say.

 

[Humminbird Greg]

Generally the external GPS Receiver will be, but mostly because it can (and should) be mounted as directly over the transducer the unit is using as you can get it. Any horizontal distance between the transducer and GPS Receiver could lead to double that distance in inaccuracy for any waypoints that are marked from the sonar. This would be in addition to the overall inaccuracy of the GPS system that we are allowed to use.