Furuno FAP5002 not staying on track in nav mode

[Zephyros]

I am running NavNet3D MFDBB with 2x MFD12 plus Furuno autopilot FAP5002 etc etc. All Furuno gear.
When tracking a waypoint using the nav mode, if there is little crosstide it seems to keep the boat more or less on track.
But with a strong crosstide the XTE keeps increasing taking it way off track.
Any ideas what could be wrong? The boat is a Nordhavn 43 running at displacement speed - around 7kts.

 

[Johnny Electron]

Do you have your advanced auto set to ON? (Pg 2-4)

If your advanced auto is ON and still having problems then your pump might be under rated or have some sort of restriction. It also could be the boat not having a large enough rudder for the hull size.