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Turning Maggie ON:




Call the Bridge (200) and ECR (290) and tell them you are deploying the maggie

Get the OK to before proceeding

Connect cable to towfish

Towfish is connected in a secure place on the fantail

Turn on power to isolation transceiver

Blue light flickers and goes off then solid green light

Launch SeaLINK software on the opposite computer that the Winfrog software is running

Ignore Repeat Functionality Disabled error for now. Okay through any Sync messages.

Power up (Ctrl-O) (May turn off if already on)

Command window will read:

Power ON

  1. Test by pressing 2 x spacebar to acquire time

Command window will read: ‘Towfish not synced’ in first line followed by ‘Setting Towfish time’ and finally ‘Towfish time was set’

  1. Enter ‘d’ command in command window to confirm parameters

This will display your output parameters in the command window and should read close to these values. (Between 013-015mA, and 00.6-00.8W is acceptable).

Output 47.6V, 014mA, 00.6W ‘

S:006 B:+47.9V T:+022.3C D:+000.4m

  1. Make sure Data Logging is set to OFF while setting up Towfish parameters


Data logging status will now be OFF  

Stop magnetometer cycling by clicking ‘Stop cycling of Mag’ icon

Command window will read: Cycling off

Check NMEA GPS data is coming in from Winfrog

NMEA Window is on bottom left just below command window

Window will be scrolling as new GPS info is being received from Winfrog software. If not receiving GPS continuously, refer to the Winfrog User Guide on either (1) Adding and Editing I/O devices through COM ports,  (2) Adding NMEA Output Device, or (3) ask the LO/Underway Tech to help connect). The NMEA to SeaSpy or Magnetometer device should be through COM11.

Get the towfish in the water, just below the water line

Towfish is just far enough out to be stable in the water.

  1. After 15 minutes to equilibrate pressure and temp, zero pressure sensor

 or ‘p’ in command window

Command window will ask ‘zero pressure Y/N’. Press Y and command window will read: ‘Zero pressure is * mV’

  1. Spool out the cable

Towfish is now at its full towed length. Refer to Maggie User Guide if unsure where to stop the spool.

  1. Sync time source

 or F7

Command window will read: ‘Time set - *current date and time* followed by ‘Setting towfish Time…’

Enter layback length (0m)

True layback offset is set in WinFrog, the GPS data coming into SeaLINK will already have this offset applied.

Command window will read: ‘Layback length changes from *.* to 0.0 (m)’

Sync GPS with towfish

  or F8

Be patient until you receive ‘Synchronization failed’ error. Click ‘Okay’  (Unsure if this step is necessary)

Click ‘Appending GPS position to Fish output’ icon


GPS Tagging status should now be ON

Turn on Auto tuning

 or ‘x’ in command window

Command window will read: ‘Auto tuning on’

Create a new logging file with ‘Start logging on a new SeaLINK file’ icon.

New file will be created automatically in C:\Exp Mag Data\EXP#

Cycle at 0.3Hz by selecting 0.3Hz icon

Command window will read: ‘Cycling at 0.3Hz’

Start logging data with ‘Toggle SeaLINK File Logging’ icon

Data Logging status will now be ON

Check signal status indicators

Status readouts located above command window

Should have NO RED indicators, YELLOW is acceptable, GREY is good

Call the Bridge (200) and tell them maggie is deployed

Open Windows File Explorer and make sure that the files are being written/updated

Go to LO office and connect monitor to the Winfrog computer running SeaLINK software

Maggie can now be monitored from LO office.


Turning Maggie OFF:

  1. Stop data cycling (STOP icon)
  2. Stop data logging (press LOG icon)
  3. Turn off power to towfish (CTRL-O letter, not number)
  4. Disconnect power to isolation transceiver (on/off switch next to blue box)
  5. Retrieve towfish being careful to spool the line neatly
  6. Spray incoming cable with fresh water and rinse towfish with fresh water on deck.
  7. Dry the brass cable and towfish connector (nose) with air. Lightly coat the brass connectors with WD-40.
  8. Remember to spray pressure sensor port with air.
  9. Let bridge (200) and ECR (290) know the magnetometer has been retrieved.

Archive Versions

SeaLINKCheatsheet.pdf - Feb. 24, 2020

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