Check their progress against Howard's plan here, (UTC is +6hrs)

Subject: N4
Date: Fri, 13 Nov 1998 15:36:18 -0600 (CST)
From: Desmond Rolf <gyre@ocean>
To: ann@portia, howie
CC: fjk1776@gergl1, norman@gergl1, wnowlin@tamu.edu

RV GYRE -- NEGOM N4 98G15 left Gulfport at 04:30 UTC 11/13/98 (22:30 Local 11/12/98).

Norman was met by Weisenburg and Albers at airport at 9:30pm and was conveyed to the dock before the ship sailed.

Finished test station. Weather cloudy fair seas 3 ft. Everything working reasonably well. Skeefum well. ADCP 38khz is working with nominal depth range of 200m at 9.2 knots, lost bottom track at 625 meters. Have lowered 38khz transducer 1 meter with no significant improvement.

Walpert reports that 38khz shows no significant improvement from test cruise. We are going to increase the number of BT pings and the number of water pings(now set at 1 each) to see if we get any improvement. Frank should ask RDI for advice on this. ADCP 150khz is performing within acceptable parameters but with slightly less penetration from previous cruises.

Norman and Steve
Steve wishes Matt and Ann were here.

Subject: ADCP
Date: Mon, 16 Nov 1998 09:51:12 -0600 (CST)
From: Desmond Rolf <gyre@ocean>
To: ann@portia, wnowlin@tamu.edu
CC: fjk1776@gergl1, howie

The 150khz ADCP is not working. Although we thought at the begining of the cruise it was giving good data, we noticed that the vertical velocities were consistantly high. Self Diagnostics indicated that it failed PT3 with a $4444 or $6666 or $6464 error message. We decided to replace it with the narrow band unit while underway. We raised the instrument about 1 foot when jammed. We stopped the vessel about 9:30 local last night and tried for about 2.5 hours to raise the ADCP. Although it would turn freely after being raised off the pins, it repeatedly jammed on something after being raised about 1 foot. We feel that either something is jammed on the transducer heads or that the bottom of the fairing around the bottom of the moon pool has been bent is such a way as to obstruct the transducers.

The captain has indicated that, although nobody felt anything, the ship may have struck the bottom off the Chandelieur Islands. The island was heavily modified by Hurricane Georges which might have formed a submerged sandbar. Evidence includes mud and shell hash in the toilets and mud in the piping leading to the watermakers. Plan is to continue on without ADCP. Our only alternative would be to hire a diver to come out and inspect the bottom of the vessel and see if they could free the ADCP. We feel that might take up to a day with no guarantee of success.

We will modifiy the output of the 38k ADCP to give better vertical resolution and better accuracy in the shallower waters. Steve, I and John Walpert are looking at this closely. The 38kh ADCP seems to be giving data down to about 200m with a hole in the data between 200 and 400 meter. Data indicated as good by the machine appears at deeper depths, but we have no way to verify its accuracy and we remain sceptical. We have also seen the that the machine indicated good bottom track at 350m when we were in 1000m of water. We are currently running it at 3 water and 3 water pings per ensemble with 32m depth bins. We will shorten bin size to 16 as we get into shallower water.

Any advice or suggestions would be welcome.
Norman and Steve

Subject: Cruise report Tues 17 Nov
Date: Tue, 17 Nov 1998 09:31:27 -0600 (CST)
From: Desmond Rolf <gyre@ocean>
To: ann@portia
CC: BASVENMD@AOL.COM, howie, wnowlin@tamu.edu

Cruise report: Tuesday AM local time should see us midway through line 09. 150kHz ADCP still down, 38kHz running but data is still considered suspect. We suspect not enough scatterers for 38kHz to pickup scattered signal. Scales analysis of SAIL and XBT (@10m) show spatial scales of 22 and 27 km in agreement with N3. Other scales are about 20 km for lines 10/11 and run from Gulfport to test stn. Doing preliminary processing of CTD data to get BTL files for merging with nutrient/bottle data. Works well. Two sperm whale sightings and night bioluminescence. Weather: fair, winds gusty to 15 kts.

report by dimarco

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Subject: report
Date: Thu, 19 Nov 1998 08:34:57 -0600 (CST)
From: Desmond Rolf <gyre@ocean>
To: ann@portia, wnowlin@tamu.edu
CC: basvenmd@aol.com, fjk1776@gergl1, howie

Weather has been good, light winds. At 0010L Thursday we are in the middle N4L08S17C. Because of the importance of 38khz ADCP to this and future deep water programs, we will try 2 RDI-recommended experiments. First after this CTD cast, we will decouple the ships engines and record data for 2 to 3 averaging periods. We will then completely shut down the two propulsion engines and record data for 2-3 averaging periods. This will attempt to assess the importance of ship noise in limiting the observed data returned thus far. Second, we will switch the 38khz to narrowband mode and run the line between here and line 7 in narrowband mode. RDI feels that this will improve penetration and data quality, but has also warned they have not extensively tested the instrument in this mode. They are anxious to see this data.

Steve has plotted and contoured all analyzed bottle data and they look good. We are prepared to throw the first drifters tomorrow on Line 7. Dana Dyer has arranged for a diver to meet the ship in Destin in Friday to assess the cause of the hangup in the ADCP well.

Steve with Norman and Doug

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Subject: cruise report 11/20 3:30z Date: Fri, 20 Nov 1998 13:30:18 -0600 (CST) From: Desmond Rolf <gyre@ocean> To: ann@portia, wnowlin@tamu.edu CC: basvenmd@aol.com, fjk1776@gergl1, howie

We learned 2 things from the 38kHz experiments last night: 1) narrowband mode marginally improves the penetration of the acoustic signal (by 1 depth bin =32m), but RDI cautions that the NB mode is still under development so data may be useless. 2) Ship engine noise has no effect on data quality. We are out of ideas for the 38 Khz and will let RDI engineers process the data post-cruise. An ex-Navy Seal is lined up to inspect the 150 kHz moonpool at stn. L05S01C on Saturday. The purpose of this is twofold. One is to assess the damage so that we are prepared to take the adcp out when we get in. The second is to fix it if possible or remove it so we can install the narrowband unit. Our best guess at this point is that something is wrapped around one of the transducers.

Other news: Since changing a diaphram on the ship's engine a few days ago, the ship is making excellent time and average's 9.3 kts between stations. Hydro data collection and processing continue with no problems. 2 drifters thrown today. 1 small whale sighting today. 2 net tows planned for tomorrow. Weather continues to be wonderful. Catfish for dinner... Fire and boat drill today. All going well and all in good spirits. Steve Doug and Norman send

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Date: Mon, 23 Nov 1998 16:18:39 -0600 (CST) From: Desmond Rolf <gyre@ocean.tamu.edu> Message-Id: <199811232218.QAA27790@ocean.tamu.edu> To: ann@portia.tamu.edu, fjk1776@gergl1.tamu.edu, tamu.edu@ocean.tamu.edu, wnowlin@tamu.edu Subject: Recovery of ADCP Cc: eshaar@ocean.tamu.edu, pam@gergl1.tamu.edu

11/21/98 We left Station N4l05S00C about 1645L. Arrive at jetty off Destin about 1710L. Divers aboard about 1730L. Divers shown top of moon pool and briefed. Divers in the water about 1740L.

Divers found that starboardside fairing was bent and that ADCP appeared to have been pushed back about 1 inch in its mount. This caused the transducer to hit the retaining ring as it was being raised in the moon pool.

Divers loosened 3 of the 4 mounting bolts in the bottom circular plate and were able to pry instrument back to clear hole. The BB ADCP hoisted aboard about 1840L. Started to installed narrowband transducer in well about 1850. Anchor up at 1900L.

The ADCP outwardly appeared ok. Considerable amounts of brown mud were found on top of the bottom bottom circular mounting plate indicating that the heads had been dragged through the mud. Mike Fredericks believes that the scratches on rear facing transducer housing occurred when we were tring to raise the transducer through the moonpool. The Captain Dana Dyer believes the damage to the moon pool fairing occurred when the vessel was drydocked.

The most likely cause of the damage was hitting a muddy bottom which pushed the instrument aft in its housing.

We will return the instrument to RDI for evaluation. The divers were paid $400. I have agreed to pay half of this cost from NEGOM funds.

We will modify the housing to prevent slippage in similar situations.

Norman 11/23/98 NB adcp is working. We will probably have to pay the department for day use for 3 days--- Saturday, Sunday and today. We will secure the adcp after the last NEGOM station. Norman

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Subject: NEGOM-4 work is complete Date: Tue, 24 Nov 1998 17:24:36 -0600 (CST) From: Desmond Rolf <gyre@ocean> To: ann@portia, mkhoward@tamu.edu, wnowlin@tamu.edu CC: eshaar@ocean

We completed Line 1 and our last NEGOM CTD (#98) at 06:30 AM local today 24 November. We logged 150 kHz narrowband ADCP data on all of the last four lines 4 to 1, concurrently with 38kHz data. All drifters have been deployed. We're enroute now to Miss Canyon to do CTD profile there and then recover mooring for Cheryl Burden. At 08:53 local time, we were at 28 57.1, 89 06.4. If all goes quickly with recovery, we should arrive Galveston sometime late afternoon tomorrow 25 November. doug sends