GROSS NAV ERROR.

Narrative

COURSE DEV DUE TO DEGRADED NAV AND HDG SYS. ON A NBOUND COURSE FROM PANAMA TO MIAMI; WE DEVIATED L OF COURSE FOR WX FROM HAVANA CTR OVER CUBA BTWN UVR (VARDER) AND TADPO. KINGSTON CTR/HAVANA AND MIAMI ARTCC WERE ADVISED OF OUR NAV AND HDG PROBS. APPROX 100 MI N OF TADPO; MIAMI ARTCC CALLED AND ADVISED 'YOU ARE ENTERING A WARNING AREA. SQUAWK 7700; AND TURN R.' I ADVISED MIAMI AGAIN THAT OUR NAV (OMEGA) SYSTEMS WERE INACCURATE AND A HDG SYS ALSO. MIAMI INITIATED NO-GYRO VECTORS BACK TOWARDS MIAMI. AFTER A CTLR FREQ SWITCH; IT WAS ESTABLISHED THAT WE STILL HAD HDG AND AT LEAST 1 VOR CAPABILITY. THE #1 VOR WAS APPROX 180 DEGS IN ERROR PASSING OVER GRAND CAYMAN. THE #2 VOR NEEDLE APPEARED NORMAL. WE ALSO HAD THE MAGNETIC COMPASS. AFTER ESTABLISHING WE HAD HDG REF AGAIN; CHANGED SQUAWK BACK TO WXYZ AND GAVE VECTORS TO MIAMI WITHOUT FURTHER INCIDENT. (NOTE: FORWARD LAVATORY FLOOR WAS FLOODED IN PANAMA REQUIRING MAINT. FLOODING FROM EITHER THE FORWARD LAVATORY OR THE FORWARD GALLEY CAUSED WATER TO RUN FROM THE BOTTOM OF THE ACFT.) WE COULD HAVE COMMUNICATED OUR HDG SYS MALFUNCTION BETTER TO MIAMI SO THEY KNEW WE STILL HAD HDG REF FOR VECTORS.