Predicted tides were applied to the data in real time: at Tutuila, Muli, Tulago, Vailulu'u and the Manu'a Islands, Pago Pago (170000) predicted tides were used with no corrections; at Rose Atoll, Pago Pago tides were used with +0.1 hr time correction and a range ratio of 0.92; and at Swains Island, Pago Pago predicted tides were used with a -0.5 hr time correction and a 1.12 range ratio.
Horizontal accuracy is 20m (no differential GPS correctors applied), vertical accuracy is depth dependent (~1% of water depth). WGS84 datum. These data are not to be used for navigation. Depths mapped range from 20 - 4800 m. Concurrent mapping was done by the R/V AHI in water depths ranging from 10-250 m with the data set being AHI-06-02; metadata for AHI-06-02 are submitted separately.
The Hi'ialakai's equipment serial numbers, software versions and sensor configuration settings are as follows:
SIMRAD EM300 multibeam echosounder Serial #: 303 PU Software Versions: 1.1.3 040427,2.0.0 040614,2.3.2 040615,2.0.1 040629 SIS Software Version: 1.0, build 117, July 2, 2004
SIMRAD EM3002D multibeam echosounders Serial #: 357 and 353 PU Software Versions: HCT: 2.0.7 040906 BSP67 Master: 1.2.7 040830 BSP67 Slave: 1.2.7 040830 PU: 1.6.8 050118 DDS: 3.17 2004/06/11 SIS Software Version: 2.5, build 47, April 1, 2005
HI'IALAKAI POS/MV Model 320, version 3 PCS serial #: 817, 474 and 295* IMU serial #: 1333 PCS Firmware: 2.16, Sep 15, 2004 and 2.21, Feb 02, 2006* Controller software: v 2.1
Seabird SBE 9/11 plus CTD: Serial #: 09P35130-0737
*Two problems were encountered with the POS/MV during this cruise. On the evening of Feb 17th (local time) the ship's POS/MV started continually rebooting. With assistance from Applanix we determined that the problem was isolated to the PCS, the rack-mounted controller box. The failed PCS has serial number 817. We moved the PCS(SN 474) from the R/V AHI to the ship after replacing the amplifier that provides power to the IMU (normally the PCS is equipped with a 24VDC supply by the ship's PCS has a 28VDC supply to drive the 50 m cable to the IMU) and were able to continue to survey. Because the IMU was not moved no recalibration was required. The PCS was moved between the ship and the AHI daily, allowing the ship to survey at night and the AHI to survey during the day. The settings for each configuration were saved to disk and reloaded at the beginning of each session. This continued until Feb 24th when a replacement unit arrived; this is SN 295. A second problem was that at some times the POS/MV would provide two different date stamps for the data, one time would be reported out the serial data stream and a different one reported out the Ethernet data stream. When this occurred the sonar data would have different time tags than the data recorded by the ISS2000 and data logging would fail. If the POS/MV was powered off and restarted the erroneous date stamp would usually disappear. Appalanix provided new firmware (v 2.21) to fix this problem, which was caused by GPS and UTC times diverging from each other by an additional second. This new firmware was installed on Feb 25th.
Hi'ialakai Lever Arm Distances and Alignment Offsets: The Hi'ialakai's Reference Point (RP) is a granite block situated 1.222 m starboard of the ship's centerline, 1.23 m above the ship's baseline/datum on the keel. The RP is located under the forward deck, in the ship's laundry room. The ship's sensors, the sonar systems and permanent benchmarks are measured with respect to the RP. Positive X means the point is forward of the RP, positive Y means the point is to starboard of the RP, positive Z means the point is below the RP. The survey waterline is defined to be at the 15' draft mark on the vessel's starboard side.
POS/MV Settings: X Y Z RP to IMU, m 0.434 0.000 -0.117 RP to Primary GPS(port),m -18.101 -2.011 -23.545 RP to Vessel, m 0.00 0.00 0.00 IMU w.r.t. Ref. Frame, deg 0.00 0.00 0.00 RP to Heave lever arm, m -14.532 -1.179 -5.234 Sensor 1 & 2 lever arms & angles: 0 0 0 Antenna Baseline Distance: 1.779
EM300 Settings: X Y Z Pos sensors 1 2 & 3, m 0 0 0 TX Transducer, m -04.091 -2.217 1.727 RX Transducer, m -06.065 -1.222 1.727 Attitude sensors 1 & 2, m 0 0 0 Waterline, m -3.26 Roll Pitch Heading TX Transducer, deg 0.00 0.00 359.96 RX Transducer, deg 0.00 0.00 0.05 Attitude 1, deg -0.20 0.00 0.00 Attitude 2, deg 0 0 0 Stand-alone heading, deg 0
EM3002D Settings: Pos sensors 1 2 & 3, m 0 0 0 Sonar head 1 (port), m 04.439 -1.479 1.560 Sonar head 2 (stbd), m 04.441 -0.963 1.559 Attitude sensors 1 & 2, m 0 0 0 Waterline, m -3.26 Depth sensor, m 0 0 0 Roll Pitch Heading Sonar head 1 (port), deg 40.153 0.00 0.27 Sonar head 2 (stbd), deg -39.918 0.00 358.18 Attitude 1, deg -1.25 1.1 0.00 Attitude 2, deg 0 0 0 Stand-alone heading, deg 0
Resource Description: EM300 and EM3002D Multibeam Sonar Data from Cruise Hi'ialakai HI-06-02
These data are also archived through NOAA's National Geophysical Data Center at <http://www.ngdc.noaa.gov/mgg/bathymetry/multibeam.html>
Data Format - Generic Sensor Format, as described in <http://www.ldeo.columbia.edu/res/pi/MB-System/formatdoc/gsf_spec.pdf>