U.S. GEOLOGICAL SURVEY BRANCH OF ATLANTIC MARINE GEOLOGY MEMORANDUM MARCH 22, 1988 To: Cruise-Report Distribution (see p. 2) From: Jim Robb, Peter Popenoe, Co-Chief scientists Subject: Administrative Cruise Report: Farnella 87-4, East Coast GLORIA survey-leg 4 1. Ship: R/V Farnella 2. Cruise: 87-4 (leg 4 East Coast GLORIA Survey) 3. Parent Project: East Coast GLORIA Survey 4. Funding Agency: USGS SIR 5. Area of Operations: offshore parts of U.S. EEZ between 34 N and 37 N 6. Cruise start and end dates, ports: April 27, 1987, Woods Hole, MA - May 8, 1987, Norfolk, VA 7. Co-Chief Scientists: James Robb, Peter Popenoe-USGS AMG 8. Cruise Data Curator: Nancy Soderberg-USGS AMG 9. Scientific Party: IOS Coordinator Derek Bishop IOS (UK) Geologist Quentin Huggett IOS (UK) GLORIA engr. Chris Flewellen IOS (UK) ABC Computer Doriel Jones RVS (UK) Mech. tech. Graham Lake IOS (UK) Photographer Emma Woodward IOS (UK) Watchkeeper Linda Sheetz USGS PMG Watchkeeper Andrew Tizard Marconi (UK) Watchkeeper Bill Wright USGS staff 10. Ship's Captian: Mike Patterson 11. Purpose of Cruise: GLORIA (long-range sidescan-sonar) mapping of East Coast U.S. Mid-Atlantic region via contract with IOS (Institute of Oceanographic Science, United Kingdom). This was a "gap filling" period to adjust for time lost and survey area not covered because of bad weather during Legs 1 and 2 of the effort to map the East Coast U.S. Exclusive Economic Zone (EEZ). 12. Navigation Techniques: Primarily Loran-C, using an MNS 2000. Auxiliary and backup systems included 2 Loran-C units, a Northstar 7000 system which was also used to provide steering direction on line, and a Megapulse Accufix 500, used primarily for backup. Transit satellite fixes were acquired using an MNS 2000. MNS data, both Loran-C and satellite, were recorded on the IOS ABC data system as lat-lon. Loran-C time differences from the Northstar 7000 were also recorded on the ABC system. The Megapulse Loran-C data, TD's and lat-lons calculated using a nominal ASF correction, were recorded on 5-1/4" floppy discs using a USGS Loran-C processing and recording program on an IBM PC. 13. Scientific Equipment: IOS GLORIA system (Geologic LOng Range Inclined Asdic) near-surface towed (~50m deep) 6-kHz sidescan sonar system, 6-11 nmile range (each side) depending on water column sound- velocity profile. IOS 2-channel seismic-reflection profiling system using a 160 cu. in. airgun, Geomechanique streamer, signal digitized and displayed on a CRT in wiggly-trace profile using a Masscomp computer (USGS), and recorded on 9-T tape. Towed proton-precession magnetometer (USGS Geometrics gradiometer w/one sensor) IOS 3.5 kHz high resolution profiler (external fish) IOS 10 kHz precision echo-sounder (external fish) Seas III XBT system (NOAA) 14. Tabulated Information: a. Days at Sea: 12 b. Data acquired: GLORIA images about 1750 nmiles SRP profiles on line 3.5 kHz profiles about 3240 km (1.5 days lost, 1590 nm., 2950 km) 10 kHz prof. soundings about 19 xbt profiles, 0700 and 1900 daily Magnetometer 3240 km Appended: Track chart Report by Derek Bishop, IOS Coordinator Distribution: BC Halley ABC Knebel GC Booth AC Dillon OCo Aldrich DL Soderberg ADMIN Gail Folger OCR O'Brien Contents: page no. 1.) Itinerary 3 2.) Cruise participants 3 3.) Cruise objectives 3 4.) Narrative 4 5.) Equipment reports 7 6.) Results 8 1.) Itinerary Sailed Woods Hole 1100 27 April 1987 Started Survey 1100 28 April 1987 Completed survey 1430 7 May 1987 Arrived Norfolk Virgina 1600 8 May 1987 2.) Cruise participants USGS personel: Kooker, Larry Technician Popenoe, Peter Co-Chief scientist Robb, Jim Co-Chief scientist Sheetz, Linda Geologist Soderberg, Nancy Archivist Tizard, Andrew Technician Wright, Bill Geologist IOS personel: Bishop, Derek GLORIA Flewellen, Chris GLORIA Hugget, Quentin Co-Chief scientist Jones, Doriel Computing Lake, Graham Technician Woodward, Emma Geologist 3.) Cruise Objectives This cruise was part of a joint United States Geological Survey (USGS)/Institute of Geological Sciences (IOS) program to survey the United States Exclusive Econmic Zone (EEZ). In this, the fourth year of the program, the survey has concentrated upon the U.S. East Coast. For this cruise, the area to be surveyed was in the region of the Hatteras Canyon off Carolina. The activites of this cruise hinged around the Gloria sidescan system and the production of a sono- graphic mosaic. Supplementary data were collected using 10kHz and 3.5kHz echo sounders, seismic reflection profiler (SRP), magnetometer and XBT. 4.) Cruise Narrative 27 April 1987 (117) Monday We sailed at 11:00 this morning and by 14:00 had got out of the bay and into the open sea. Before sailing Chris Flewellen discovered that both the 3.5 kHz fish needed servicing. He discovered that one of the fish had a broken Canon connector and could not be repaired through lack of spares. By 15:00 the weather had worsened and most of our company had retired with mal de mer. 28 April 1987 (118) Tuesday By morning the weather had moderated and we started launching the gear at 11:00. By 13:00 all the gear was launched and we turned onto the first line. At 15:00 we suddenly encountered the Gulf Stream which reduced our ground speed to 5 kts. There was nothing we could do about it but press on. 29 April 1987 (120) Thursday Data of the 3.5 kHz system became very poor during the night, and by the morning were almost absent. Line 1 progress was still being retarded by the Gulf Stream and our ground speed was down to 4 kts. It was decided to circle the ship to remove the 3.5 kHz from the water and replace internal bits that had failed. Data acquisition on line ceased 12:31. Course change and fish retrival took place 13:00. The fish was back in the water by 14:35; however, the problem was not fixed. We reoccupied the line at 15:00 to check whether weather would allow fish work while on line. We were back on line at 15:10 and continued to work on the 3.5 kHz problem to no avail. During the day the weather steadily worsened. With increased headwinds we steadily ground to a halt, and the ship was beginning to pitch badly. 30 April 1987 (120) Thursday By 01:00 the ship was only making .95 kts over the ground and using full power; the main engines could only just cope with the 30+ kts headwinds. We therefore abandoned line 1 and turned south to start line 2. The weather improved hereon, and when we turned at the end of line 2 to come back southwest for line 3 we could make >7 kts. over the ground. Unfort- unately GLORIA data had become progressively degraded by incipient cable failure starting about 2300. 1 May 1987 (121) Friday The GLORIA data worsened through the morning until finally it was decided to undertake a cable change. At 07:15 we discontinued line 3, changed course in order to run an intermediate returning line with 10 kHz. while working on the gear. At 1026 airgun shut down to pull streamer in prep. for GLORIA recovery and cable change. At 10:36 the magnetometer was retrieved, the the GLORIA vehicle at 10:50, and 3.5 kHz. fish at 11:15. Following a small roundabout we proceeded northeast between line 2 and 3 by 12:50, so line 3 can be reoccupied near 23:00 (local) last night position. Both the GLORIA cable change and the 3.5 kHz. were worked on during the day; once again nothing could be found wrong with the 3.5 kHz system so it was prepared for launching with the GLORIA. The GLORIA cable change was completed by 16:55 and the launch point reached at 18:20. Both the GLORIA and the 3.5 kHz fish were launched and working 19:00. The 3.5 kHz continues to baffle us, however, because it will not work on all four transducers. If we only use two of the transducers the system appears to work well, we will obviously be hearing more of this later! By 20:24 we had restarted line 3 at the same point we had passed it at 23:30 (121), and the continuation of that line has been called line 5 (note that lines 3 and 5 are on the same track and line 4 is 10 kHz P.E.S. only). Sound propogation is better now (reaching at least 8NM), and we are making good groundspeed (8 kts). One of the GLORIA PPA circuits (port s/c) keeps tripping out so the watchkeepers have to keep on their toes. 2 May 1987 (122) Saturday Survey going well today in fine weather. A small bonfire on the accommodation deck caused people to wake with a start! When we turned north to run line 6 some odd 'line dropout' type artifacts appeared on the GLORIA records. At first it appeared that the 'zero yaw' software became confused when faced with a heading of 000deg. When the automatic yaw corrections were switched off (ie. zero yaw switched to on position), the artifacts ceased appearing. This was later shown not to be the case as the 'line dropouts' appeared on courses other than 000deg. We don't know what causes them; it appears as though some of the data from the port side is deleted and added to the star- board side. The weather stayed calm all day and the survey went well. 3 May 1987 (123) Sunday Early this morning an irate chinaman had to stop his ship when informed by the bridge that the 'ball diamond ball' signal meant that he risked fouling his prop if he passed our stern within 2 NM. "Oh bloody hek, you British impeliarist lotters." 4 May 1987 (124) Monday A fairly uneventful day, except for a routine gun change just before mid- night. The weather is still really good. 5 May 1987 (125) Tuesday Irregularities with Loran-C navigation led to wiggles in line 10. Both Northstar and Megapulse systems jumped during the day. The ships track is south on the planned line. At about 12:00 the heading was as much as 12 deg. northeast of the track to be made good (44 deg. vs. 56 deg.) Consider- able discussion of Megapulse asf corrections and unknown Northstar lat-lon alogorithms was pursued. 6 May 1987 (126) Wednesday Loran-C plots for days 125-1130 to 126-1200 show Megapulse to jump off (southeast) at about 11:30 and jump back on at 12:40 day 125 in addition to a Northstar jump at 1610 day 125. Transit satellite fixes from the bridge MNS unit showed that Megapulse gave gave correct navigation after the jump back. A Yankee naval vessel to starboard insists on ownership of the ocean... "Christ on a crutch, the socialist laborite scientist brits." Any system poltergeists today were attributed to the Farnella being swept by "smart, high-tech, anti-Soviet radiation." The airgun failed at about 22:00 and was found to be in need of considerable attention. The SRP LSR (a Raytheon) died at about 18:00 and Larry had to modify one of the circuits as replacements were not available. He had it fixed and running by midnight. 7 May 1987 (127) Thursday Some strange artifacts started appearing on the 3.5 LSR just after midnight; they consisted of streaks across the record similar to event marks. They didn't appear to have a regular time base, and some of them 'wrapped' around the record. There are at least three U.S. Navy ships roaring around with streamers out (3 mile clearance requested) and we think that these are responsible for the 3.5 kHz noise. At 02:06 and 30 seconds there was a total power loss of the clean 220 v. power supply. GLORIA, 10 kHz, 3.5 kHz, SRP and the ABC computer shut down. At 02:24 we broke the line as too much data had been lost, and the gap was too great. At 02:43 power was restored and the laborious task of resetting all of the instruments began. By 03:30 all the systems had been restarted and we had begun the final turn to rejoin the survey line (line 12). At 03:49 we were back on line and had rejoined it at the position we were in at approxi- mently 01:55. The cause of the power failure was narrowed down to the paper processor in the photo lab. It had already tripped out the photo lab power once before (at about midnight). Emma was working with the machine, and it appeared to leak. The 02:06 power failure occurred after Emma had cleaned (checked for leaks) and refilled the processor. She heard a bang come from the processor plug as the power failed, the ergo and the processor caused the failure. At 14:30 we stopped logging to bring this leg to a close. The survey was finished halfway down line 12 at 34deg 06.3' N 72deg 12.6' W (Northstar position). All gear was onboard by 15:30 and we were underway for Norfolk, ETA 16:00 tomrrow. 5.) Equitment Reports GLORIA - GLORIA was in the water for a total of nine days and three hours. In that time 24,100 sq. NM. of seafloor were insonified. At first, data quality suf- fered due to a faulty cable. This resulted in 11 hours of down time for a cable change (see narrative). Apart from the cable, the main problems experienced were occasional PPA trips (port side) and hitherto unexplained artifacts which resulted in what appears to be line dropouts (see day 122 in the narrative). Propogation was variable and depended upon the Gulf Stream. At the start of the survey we were only getting 7 miles range. Once out of the Gulf Stream however, we could rely on 9 miles range, and we could space our lines accordingly. We had selected the lines so that they were parallel to the Stream in order to reduce vehicle set and yaw. As a result we were being pushed of headed by the Stream so that our ground speed varied from 4 to 12 kts. P.E.S. - The echo sounder worked without fail throughout. 3.5 kHz - Considerable problems were experienced with the 3.5 kHz echo sounder which resulted in approx. 1.5 day of lost data. The problem has not been solved, so the reader will have to wait until the next cruise report for the conclusion of this mystery! S.R.P. This was comprised of a single airgun (160 cu.in.) and two channel streamers. It was run at a ten second firing rate and filtered into two records, from 15 Hz and 75 Hz to 150 Hz The system ran well with only 3 hours down time caused by a gun failure (see day 126). Magnetometer - The magnetometer worked without fail throughout. Navigation - Our navigation was obtained from a combination of four systems: dead reckoning, transit satellites and two Loran-C receivers. We relied mostly on the Loran-C systems, only resorting to others when necessary. The local Loran-C network was received by two systems on board, these were Megapulse and Northstar. The different systems calculated our position using different algorithms and so the calculated position varied slightly. As we were at the limits of the network, both systems occasionally jumped where the receivers missed transmitted pulses. XBT - Nine 760 meter depth XBT were launched on different days at approx. 18:00. This was done to build a record of temperature profiles for the study of GLORIA sound propogation problems. The data were also sent to NOAA for inclusion in their data bank. 6.) Results We surveyed approximently 18,000 sq.miles of the seafloor. The mosiac and profile data collected on board showed the main sediment pathways of the continental rise where they were being forced to the south and west by the Hatteras Transverse Canyon. The eastern end of the Hatteras Canyon (where it meets the Transverse Canyon) has developed an impressive erosional escarpment which on the 3.5 kHz record appears to have cut into hard rock. In the northwest of our area, sediment from the Albermarle-Currituck slide could be seen spilling down towards the Transverse Canyon. We were unable to complete the survey planned for this leg because of a combination of bad weather, propogation and cable problems. It is planned that the survey will be completed on the next leg (Farnella 5/87) where the fate of the sediments in the Transverse Canyon may be revealed.