..
Geoid Model are used only if you want to do Grid Conversions referenced to Mean
Sea Level
The Geoid Model supports a *.GEO file from Geoid99
and Geoid03. It is used to calibrate your system to tide
gauge or benchmark data when you are using RTK tide
corrections. Refer to the following figure to determine
which geoid file pertains to your survey area.
http://www.hypack.com/new/Support/Do...1/Default.aspx