1. PORT ROYAL (CG 73) GROUNDING

2. Overview
Following a 112 Day DSRA, USS Port Royal got underway for Sea Trials. While conducting a RHIB transfer of ATG Air personnel, Port Royal ran aground off the coast of Pearl Harbor.

3. Initial Data
Scaffolding removed from bridge wings until 30 minutes prior to underway
OOC equipment:
Centerline and Chart table SPA-25G
Fathometer (thought to be operational)
Underwater log (Pit Sword)

4. Sequence of Events 0730: Stationed Sea and Anchor Detail
0845: Underway from Pier B7
0856: Loss of Gyro reported (in the turning basin)
XSIT: Fathometer read a steady 11-12ft (Determined to be OOC)
XSIT: DFGMC variation was 6 degrees vice charted 10 degrees.
0856: Troubleshooting revealed that only the gyro repeater on the SCC was not indicating ships head.
Helmsman shifted to magnetic heading
Navigation shifted to relative plot

5. Sequence of Events 1141: Steering checks conducted (SAT)
1158: Shift to AUX gyro
1201: Shift VMS primary input from GVRC to FWD RLGN
1528: Start DLQ’s and SOVT’s
1805: Flight Ops complete
1923: Set modified Nav detail at 8nm
Established a 1nm by 1nm OP BOX
1201: At this point VMS Dead reckoned the ship three times and plotted to ship 1.5 nm from previous position.
PLGR was not used
1923: MOD nav detail consisted of Nav evaluator and QMOW – not in accordance with NAV bill.

6. Sequence of Events NAV Evaluator took over plotting role.
Id’ed two tugs in tow and an anchored tanker. Plotted tanker in OP BOX (erroneously) and shifted OP BOX approximately 500 yards further north.
1941: Boat Officer recognizes that magnetic bearing given does not correlate. Attempted unsuccessful communication with Bridge.

7. Sequence of Events
Lookout(U/I) reported waves breaking forward of bow. XO noted seeing silt visible.
2003(approx): Soft aground
2040: Hard aground

8. RLGN’s
LATTITUDE INFO WAS GOOD BUT THERE WAS A RAMP IN THE LONGITUDE INFORMATION THAT LED TO A LARGE POSITION ERROR IN THE AFT RLGN
THERE WAS NO EVIDENCE OF A 72-HOUR CALIBRATION.
THE 20-HOUR CALIBRATION WAS 10 DAYS PRIOR TO GETTING
UNDERWAY.
THE LAST RESET PRIOR TO GOING UNDERWAY WAS TAKEN FOUR DAYS EARLIER, SO THE SYSTEM WAS NOT GETTING GPS RESETS.
THE VELOCITY REFERENCE WAS SET TO VMAN=0 WHILE UNDERWAY.
THE SYSTEM WAS NOT SLEWED OR RESET FROM THE TIME IT LEFT UNTIL AFTER THE INCIDENT.
THEY WERE OPERATING IN AN AREA WITH HIGH GRAVITY DEFLECTIONS.
THESE FACTORS LED TO A LARGE POSITION ERROR WITH THE GPS INTERFACE NOT ENABLED.

9. Findings Loss of Gyro DFGMC 6 Degrees vs expected 10 Degrees
VMS input shifted to RLGN
Silenced/Ignored VMS alarms
MOD NAV Detail
RLGN only had a 20 hr CAL vice 72 hour CAL
RLGN not getting GPS resets
Qualified lookouts
Unscheduled RHIB transfer
CO’s first underway
No DR or set and drift on charts
Deck log entries inadequate
Relied on VMS without question
Loss of Gyro: SCC only
Alarms: 400 position discrepancy in total
Nav detail: minus a second QMOW / CIC not informed
Lookouts: Only U/I’s on station. Qualified were FSA’s.
Deck logs: incomplete course/speed/rudder info. Evolutions were not recorded.

10. Conclusions
Reconstructed track shows approximately a yard offset to the East
Labeled fixes as satellite fixes when VMS aligned to RLGN.
Ship did not remove all way when position in doubt
Total damage cost = $20,000,000

11. Questions?