Nobody suggested turning people down, but clearly challenging your operating ideas and concepts is something you think unacceptable. Hypocrisy per chance?
no but don't dress them up as equal or better in capability when it is clear they are not.
So GMAP 1 isn't in fact a ground mapping mode, its a search mode. If they use different different pulse width and a lower PRF in GMAp2 they are just gaining range, not resolution.
The position is still derived from GPS as that is what tells your moving map display where you are (the graphic overlay if you like). AIS is too slow to update to be used and is most definitely an area weapon. GPWS uses your same GPS position.
So, in essence, you can only close to small distances from land if you have an accurate GPS position and a radar return - then you compare what the GPS tells you (via the graphics overlay which clearly needs to be very accurate) with what the real-time radar returns are telling you.
Different sea states and tide level all affect what land returns the radar sees whereas your coastline graphic (OS map display) will probably only indicate mean high water springs rather than the Lowest Astronomical Tide so there may be a massive difference when the tide is out - hence the need for a good quality, correctly processed radar picture.