Peter Wiebe's hand-written notes from MOCNESS ship log book regarding tapes, etc.
transcribed Mar. 1, 2004 NJC
Ship speed ~2 knots for all tows
Both Œ" and 9-track tape-recorded most tows.
Mesh opening of nets = 333 microns
CH125 Aug. 1975
M1 Sargasso Sea to 200m, night. Station 2. Aug. 4, 1975. Tow ok. All angles are high by 8
degrees and volumes could be low by 15%. Net 1 sampled between 100 and 195m a bit extra
due to level wind problem on GEOSECS winch: 2035 wire paid out to get level wind fixed: 191m
down to 194m coming in slowly: only paid out for 1 minute or so. 2037: stopped again at 194-
195m. 2037: coming in again. Net 2 fired ok. Net 3 fired ok. 2055: wire coming in at 10m/min.
For most of tow, wire in at 10m/min. Note: net 8 fill of radiolarian colonies.
M2 Sargasso Sea to 800m, night. Station 2. Aug. 4, 1975. Tow ok. All angles are high by 8
degrees and volumes could be low by 15%. Net 0 sent down to 955 (1600 meters wire out) then
held there until angle and depth stabilized. Tape recorder #9984 turned on at 2323 with net 2
open. We forgot to turn it on at bottom of tow. Note: every time we push net command, angle
changes dramatically by increasing also net response is not working and hasn't since beginning
of tow (as net 4 opens).
Tow was successful all 9 nets were successfully opened and closed at the right depths.
The net response indicator was tripped 8 times while shooting the net at ~50m/min while
steaming between 1.2-1.6 knots. During shooting, MOCNESS angle was ~18 deg. We paid out
1600 m wire and then speeded ship up to 1.9-2.0 kts and then let net which sank to 950+ m fly up
to 800m. At 800m, net 1 was opened.
Net response failed to work for entire hauling sequence. However, we could see when a
net was tripped by a radical momentary increase in the frame angle. Flow far each net will have
to be calculated by difference but estimates should be as good as if the net response had worked
properly.
On this tow, we had planned to start the tape recorder at the time when net 1 was
opened but we forgot and Polloni discovered our mistake during the time net 2 was opened. This
set of samples was beautiful.
M3 Sargasso Sea to 200m, day. Station 2. Aug. 5, 1975. All angles are high by 8 degrees
and volumes could be low by 15%. We got net responses while shooting the net wire angle
dropped off to 30 before I had ship speed up to 2.0 kts. Start haul coming n at 10m/min. Net 1
response: net 2 response: net 3 response got good net response until net 8 (top net no
response). Also got spurious responses (13, 14, 15) between nets 7 & 8 (angle dropped to 38
deg about this time). Note: snap hook holding bottom of net 6 and top of net 5 broke off. Nets
had reasonable collections but catches shouldn't be considered quantitative. No apparent reason
for snap hook failure. [see M4 note]
M4 Sargasso Sea to 800m, day. Station 2. Aug. 5, 1975. All angles are high by 8 degrees
and volumes could be low by 15%. Net 5 response in shooting net right at surface. Ship's speed
too slow! 2 more responses at 175m. We had a hard time getting the net at depth of 800m.
Note: the angle of the CTD sensor was corrected after this tow. It was 53 deg. rather than 45
deg.
1700: This is probably the best MOCNESS haul to date. Wire was brought in at 35m/min
and nets fished each depth interval very uniformly. There were no major screw ups except that
the net response indicator still is being tripped by the nets' sides in shooting and right at the
surface at the end of the haul.
In shooting, the problem appears to be that the net is moving through the water too
slowly. I.e. at 1.5 to 2.0 kts and 50m/min pay-out. The net is moving forward about 46.5-
41=5.5m/min or 62-41=21 m/min whish is œ to 1 kt far too slow. The solution is to shoot the net
with the ship moving ahead at 3 kts at 50m/min to give a net speed of 1.5 kts.
2100: Must now way that this was not best tow. Net 4 was ripped almost all the way
across the top and the snap hook holding bottom of net 4 and top of net 3 on net release indicator
side broke off. Snap hook was caught between nets. Did it happen at the surface?? Catch for
both nets 3 and 4 looked ok. We modified the net response indicator.
M5 Ring station to 800m, night. Station 3. Aug. 7, 1975. First start at 1956 but flow meter
hung up. Brought net up and fixed flowmeter. Second start down at 2010. On this tow we
started net going down ~15m/min and ship speed ~2.5 kts. When net was at 70m depth, sped
ship up to 3.0 kts and paid out at 50m/min. Once wire was at
.(angle probably off by 8 deg).
Tape change at 2149. No net response on nets 6 or 7.
[Did not get data transferred from 9-track tapes: njc 3/1/04]
M6 Ring station to 200m, night. Station 3. Aug. 7, 1975. Good set. No net responses.
Down at 35m/min, in at 15m/min.
M7 Ring station to 200m, day. Station 3. Aug. 8, 1975. We got two net responses when we
first started net down, so we brought net back up to the surface to check it. Net responses were
spurious, no bars released, so we sent the nets back down (500 mwo).
M8 Ring station to 800m, night. Station 3. Aug. 8, 1975. From 540-640 meters, angle
dropped off to ~18 deg. for no apparent reason. Flow also dropped. (Bad tow.) All nets closed
before got to surface. Net response also did not work. Not sure can get much out of samples.
Morning after examination showed that the top of net 0 had broken loose (another snap
ring failed). This probably explains why sudden angle change to 18 deg. occurred while shooting
the net. Check of net response indicator showed nothing wrong with reed switch and apparently
nothing wrong with the wire and connectors. One of the male EO plugs was corroded and this
may possibly have caused a bad connection in the pressure case bulk head connector.
Spent day of 9 Aug. refitting net bars and upgrading electrical cables. Main wires from
CTD to conductivity cable were not up to par, too much resistance. This was probably
responsible for varying strength of signal received at computer.
*Note Sept. 4, 1975: We found that net 1 closed and net 2 opened at about 755m depth without a
command from the surface. This explains problem with nets all being closed at the surface.
Samples probably all ok except 100m to surface was not sampled on this tow.
M9 Ring station, night. Station 3. Aug. 9, 1975. Tow no good. I turned computer on for
this one (first time). Motor drive did not work. Aborted tow after trying 2 nets. Reset on deck,
tested, and sent down attain for MOC#10. Single oblique sample prescued (sic?).
M10 Ring station to 200m, night. Station 3. Aug. 9, 1975. Note time on print out is 1100
instead of 2300. Beautiful tow. No failures apparent at end. [Very little data recovered from 9-
track tape: njc, 3/1/04]
M11 Ring station to 800m, day. Station 3. Aug. 10, 1975. Started Œ" tape at 8362-8, then
turn off. 0932: start tape again. Had some trouble with computer print out. Lost net volume for
net 4. Tow excellent in all other respects. Pressure offset = 4.0m on surface coming up.
Usually 6.0 going down. Sample from net #1 lost bucket fell off.
[poor retrieval from 9-track, very little data: njc, 3/1/2004]
M12 Sargasso Sea to 200m, day. Station 4. Aug. 11, 1975. 11 August. Tape on at 905,48,
reading 0000), Down to 240 m with net 0 let it stabilize, then hauled in at 8m/min and opened
net 1 at 200m. Beautiful.
[poor retrieval from 9-track, very little data: njc, 3/1/2004]
M13 Sargasso Sea to 800m, day. Station 4. Aug. 11, 1975. Net put in water but Ortner
forgot to pull flow meter string so had to bring it back to surface. Ortner then pulled string in air so
got 16 flow counts or 84 m^3 in air. Stop recorder at 1216 (260m) will restart on upswing. Angle
of net dropped to 20's once net was below 300m so I had ship speed up to 2.5 kts. During tow,
sky clouded up and by end of tow rain pouring. Sea still calm.
[poor retrieval from 9-track, data seems to be from 50m above sea level to 400m below: njc,
3/1/2004]
M14 Sargasso Sea to 800m, night. Station 4. Aug. 12, 1975. Had a hard time getting nets
down. Paid out 2300m wire rather than usual 1900. Came in at 25 m/min. Calculations indicate
that net was moving about 3 kts at 200-600m depth, ship's speed ~1.9kts. Net 6 cod end bucket
broke under water, sample lost.
M15 Sargasso Sea to 800m, night. Station 4. Aug. 13, 1975. Tow to replace net 6 from
MOC-14, 300-200m. One net response going into the water before it hit the water. Only 1 net to
be fished. No net responses. Tow no good net opened and closed together. No sample.
M16 Slope Water to 200m, night. Station 5. Aug. 14, 1975. Turned on Œ" tape t 2005-43 at
75m depth going down. This tow went well. Had small problem with NR not clearing NC and flow
but it was decided that it had to do with signal fading in and out rather than malfunction down in
underwater unit. Pressure offset formula in CTD acquisition program appears to be incorrect and
we have 2.75m error in the corrected depths on the computer tapes and printouts. All data
collected to date have error is MOC 1 to 16.
M17 Slope Water to 200m, day. Station 5. Aug. 15, 1975. Œ" tape started at 1012-15, 154m
depth. Had problems with data acquisition 9-track tape. Didn't get header on or 1st 12 to 15
records. This will mean some data processing problems with CTD3 program. We came up twice
as fast on th8is haul as on previous 0-200m hauls to reduce amount of catch somewhat. Looks
like a very nice haul. Pressure offset wrong as noted in M16. Two files on mag. Tape 1st file is
data, 2nd file is header.
M18 Slope Water to 800m, day. Station 5. Aug. 15, 1975. Œ" tape on at 1231 for up trace.
Had hard time flying this net to depth and getting it to stabilize. Ship was slowed down too much
and when we started hauling the net in, it rose very slowly. Except for deep fishing, this tow went
well. Pressure offset wrong as noted in M16.
M19 Slope Water (edge of Gulf Stream) to 800m, night. Station 5. Aug. 15, 1975. Œ" tape on
2037 when net 0 started to be hauled in. Plot of temp and salinity versus depth: black=down
trace and blue = up trace. Very nice tow.
M20 Slope Water to 800m, night. Station 5. Aug. 16, 1975. Two deep nets fished in 150m
intervals so that we could sample upper 100m in 2 steps: 100-50 and 50-0 where there is a
pronounced thermal break and start of thermocline. 10.55C @ 50m. Looks like a good tow. Net
moving through water at ~3 kts for most of tow.
M21 Slope Water to 800m, day. Station 6. Aug. 17, 1975. Œ" tape started at bottom of tow.
Black=down trace; green=up trace. Very nice tow; no problems.
M22 Slope Water horizontal tow at 350m, day. Station 6. Aug. 17, 1975. Œ" tape started on
1227. Had a problem with frame synch which coincided with net command on net 1. As a result,
lost 2 min. of recording and in process of getting synch back we dropped net 1 and opened net 2.
Beautiful tow after initial problem. Net frame stayed within 350 +/- 1 meter.
BCO-DMO Blog
©2024 Biological and Chemical Oceanography Data Management Office.
