Raytheon Bidata ST 40
Thorsten - I have a similar problem with the unit and have not gotten around to making an adjustment. The precvious owner installed the unit and I have no documentation. One question: have you compensated for currents? (since the GPS measures speed over ground and the instrument measures speed through the water). My delta is approximately GPS = ST40 + 1.5 kts. But, the delta is less at low speeds.
When you figure out how to make the adjustment, I''d appreciate a note.