Seaglider Ballasting Checklist¶

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Mission:  ________________________________   Seaglider ID:  _____________

Engineer:  ________________________________   Date:  ________________

1. Setup¶

• Trim sheet updated for every change since last ballast (sensors, batteries, VBD, fairings, wings/rudder)
• Target density for the mission written into the trim sheet — and checked if the glider just came back from service
• Lead and foam inventoried: each piece weighed, position noted, every hull face photographed
• Wings and rudder weighed; set fitted recorded
• Freshwater tank filled, deep enough to fully submerge the glider vertically (≥ ~2 m)
• Hanging scale / load cell rigged over the tank
• Suspension line ready (ties off at the rudder)
• Comms cable available and connected, with slack — no surface expression
• Antenna left disconnected and dangling free

2. Dry Weight¶

• Complete glider (wings, rudder, everything) weighed dry — record mass M
• M compared with the trim sheet's summed mass — difference: ______ g (tens of grams OK; hundreds = find the error)
• Glider soaked overnight, fully submerged and vertical, in the tank

3. Tank Density¶

• Tank temperature recorded (and salinity, if not freshwater)
• Tank water density computed

4. Weight-in-Water at Multiple VBD Positions¶

• Weighed in water at ≥ 5 VBD positions (e.g. 2000 / 2250 / 2500 / 2750 / 3000 counts)
• volmax computed at each position
• All values agree to within ~±5–10 cc (outliers re-checked)
• Average volmax recorded: __________ cc

4b. Neutral-Point Trim Test (if used)¶

• Predicted $C_VBD / $C_PITCH for tank density taken from the trim sheet
• VBD stepped to neutral mid-water, pitch to level, roll swept and centred
• Observed $C_VBD ______   $C_PITCH ______   $C_ROLL ______ recorded with tank density
• Trim sheet calibrated to the observed centers ("mystery mass")

5. Weight Adjustment¶

• Target thrust and target deployment density entered into the vis Ballast worksheet
• Lead added/removed per the worksheet's recommendation
• Maximum thrust in target water checked — aim for ~250–300 cc
• Pitch-mass stroke near nominal (~70 %) after lead changes
• $MASS, $C_VBD, $C_PITCH updated on the glider and in sg_calib_constants.m
• ±100 cc uncertainty accounted for in the deployment plan

6. Before First Water Time¶

• Spare foam, lead and tools packed for on-deck adjustment; crew briefed
• First dive planned as a tethered / on-a-line test
• First mission is shallow, enclosed, and local — not open-ocean or deep
• Post-tank weight/volmax figures logged for this glider

Notes:

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