Familiarisation — Free Mode

Busy-traffic familiarisation on an INTEGRATED BRIDGE display AIS targets overlaid on a radar-style PPI. This mirrors a modern ECDIS/radar where the two data sources are fused on one screen: the PPI geometry comes from radar, while vessel identity, type, COG, SOG and name come from AIS.

WHAT YOU ARE LOOKING AT
The circle and range rings are the RADAR PPI (own ship at centre, or moving across, depending on mode).
The green / yellow / red triangles are AIS symbols for each tracked vessel (radar would give blips; AIS gives identity and exact vector). The triangle points along that target's COG.
CPA/TCPA is computed from the tracked velocity vectors with an ARPA-style filter ( 25 sec), so after any course change it takes time for CPA to settle on the new value same as the real ARPA/ECDIS.

DISPLAY MODES (radar heritage)
RM (Relative Motion) your ship is PINNED to the centre of the PPI. Targets move with their RELATIVE vector (motion as seen from your deck). Channels, TSS zones and coastlines slide past you. Classic radar picture.
TM (True Motion) the world is fixed. Your ship moves across the PPI on its true ground track; target triangles follow their OWN true courses. Useful for close-quarters geometry and traffic patterns.
The RM/TM button shows the mode you will switch TO tap it to toggle.

HELM (bottom strip)
COG 10° / 1° / +1° / +10° autopilot heading setpoint (ship slews toward it at a realistic rate per vessel type).
REV / + REV engine order, ±5% of full revolutions per click (fine adjustment; hold to ramp).
DEAD SLOW commands 2 kn ahead (useful for Rule 19(e) / restricted visibility).
N engine stop (0%).
EMERG ASTERN crash-astern bell, commands 100%; once stopping, tap + REV to ease the astern bell.
The value boxes show the COMMANDED settings (autopilot heading, telegraph position). The HUD in the top-left shows the ACTUAL COG/SOG the ship has reached they lag the command because of turning inertia and engine response, exactly like real life.

PPI / SIM CONTROLS
RNG + / PPI range 3 / 6 / 12 / 24 NM.
PAUSE freezes the simulation.
×1 / ×10 / ×30 time compression.
RM / TM see above.
FULL fullscreen.

TARGET DETAIL
Click any triangle to select it. The overlay panel shows MMSI, NAME, TYPE, COG, SOG, BRG, RNG, CPA, TCPA, relative bearing and aspect the AIS payload plus derived geometry. The CPA line has a trend arrow: green = opening, red = closing, grey = steady.