Net Tow Data Sheet

Top of Sheet - Left to Right

Cruise: The number throughout this cruise...

Ship: Use JD for the David Starr Jordan, NH for the New Horizon, etc..

Order Occupied: This will be "l" on the first station occupied and "2" on the second station occupied, etc.

Station - Line, Station: Use standard CalCOFI lines and stations.

Date: Yr (year); Mo (month); Dy (day).

Hour (PST): When the net is lowered, the time is recorded using a 24 hour clock in the block marked BEGIN TOW. The block marked END TOW is filled in after the tow. It is the total time in minutes and seconds added to the BEGIN TOW time recorded at the start of the tow.

Time:

Sinking: Applies to Bongo Tow and Pairovet Tow accordingly.

Towing: Total towing time. From the start of the stopwatch to the  stop of the stopwatch. This value should be approximately 15 minutes.

Total: This applies to all tows accordingly.

Amt. of Wire Out: Does not apply to the Manta net tow.

Total No. of Angles: Does not apply to the Manta net tow.

Mesh/Port 505: This is the column used for the Manta net tow or if you are preserving both sides of the Bongo and/or Pairovet Tows.

Mesh/STB: Does not apply to Manta net tows. Applies to Bongo and Pairovet.

Net No.: This refers to a coded number assigned to each plankton net. The code refers to the type, mesh size and year of fabrication. If a net is changed due to an irreparable tear or any other reason, this number must be changed to coincide with the replacement net.

Meter Number: This is the serial number, usually 4 digits, printed on the graph paper around the flowmeter and also etched on the nose piece of the meter. Make sure the serial number on the flowmeter mounted in each frame is recorded. Again, if the flowmeter is replaced for any reason , the serial number for the replacement meter must be recorded.

Carryover:This refers to the difference between the FINAL flowmeter reading of the previous tow and the INITIAL reading of the present tow. If the FINAL reading is within 100 revolutions of the INITIAL reading, an OK is recorded in the block. If the readings differ by more than 100 revolutions, an "*" is placed in the block, as well as in the remarks block. Generally, if the reading is not much greater than the previous FINAL reading, then the flowmeter should be reset (by spinning the impeller in the appropriate direction) to match the FINAL reading of the previous tow. If the differences are excessive and the flowmeter is not reset, then an explanation for the disagreement, such as misread previous station, started tow over, windblown between stations, etc., is noted in the remarks section.

Final: The reading of the flowmeter after the tow is completed. This then becomes the initial reading for the next tow.

Initial: This is the reading of the flowmeter at the beginning of the tow. Generally the flowmeter can be reset by rotating the impeller until the reading matches the FINAL reading of the previous tow.

Diff.: The difference between the initial and final flowmeter readings.

Error Code: This refers to a non quantitative sample or a flow meter malfunction. T he four combinations are as follows:

0/0 No sample loss/flowmeter OK

1/0 All or partial sample loss/flowmeter OK

0/9 No sample loss/flowmeter malfunction

1/9 All or partial sample loss/flowmeter malfunction

Bucket Temp. : Surface temperature measured with a bucket thermometer and recorded in degrees Celsius.

Bottom Depth: Be sure to designate whether the depth is in meters or fathoms.

Accepted Position: This is the position (latitude and longitude) at which the station was actually occupied, and should agree with the position on the Captain's Logs.

Observer: The initials of the technician responsible for recording the net tow information onto the NET TOW DATA SHEET.

Amount of Wire Out: This does not apply to a Manta net tow. Refers to how much wire out is needed to do a Bongo or Pairovet tow.

No. of Angles: This does not apply to a Manta net tow. Refers to how many angles needed to do a proper Bongo or Pairovet tow.

No. of Jars:The number of pint or quart jars used to hold the plankton collected during the tow.

Formalin or Borate Added: After this material has been added to the sample, it should be initialed by the technician placing the material into the sample.

Alcohol Added: Per special requests.

Net Clogging: This refers to the passage of the water through the net during the tow. If the net is dirty, i.e., the meshes are clogged, the degree of clogging is marked in the appropriate box with an "X". The VERY HEAVY box can be marked with multiple X's if deemed necessary. The degree of clogging has a direct effect on the number of revolutions of the flowmeter; the heavier the clogging, the fewer the number of revolutions.

Net Washing: The net is rinsed after each tow and should be so indicated by an "X" in the RINSED block. If for some reason (heavy weather for example) the net was not rinsed, the NONE block should be marked with an "X". A heavily clogged net that does not rinse clear by usual methods should be soaked in Biz and scrubbed down to clear the meshes and the WASHED block marked with an "X".

Rips and Holes in Net: Place an "X" in the appropriate box. If a large rip occurs during the tow, so indicate and repeat the tow. Small holes can be repaired by covering with the silicone sealant provided in the tool box. If a large hole or rip occurs, the net should be replaced with one of the provided spares. Small holes in the upper 20% of the net should be noted and repaired, large holes in the lower 80% of the net are significant and the tow should be repeated.

Wind: Self-explanatory.

Sky (condition): Marked as clear, partly cloudy, cloudy, overcast, or if after dark, note"Night".

Swell: Self-explanatory. After dark, indicate "Night".

Sea (condition): Marked as calm, small, moderate, mod-rough, rough, or very rough.

Remarks: This area refers to anything out of routine that happened before, during, or after the net tow that directly affects the tow or the time of the net tow.

Last modified: 12/24/2014