User manual

Table Of Contents
4 - MMP Volume (in cc)

The formula for volume calculation is: (Item A + Item D)
1 / , or,
MMP Air Weight
MMP Water Weight / Water Density. Physically,
this is the mass of the water displaced by the profiler divided by the
fluid density.
5 - MMP Compressibility Constant (in cc/db)

This is experimentally a constant of 0.3.
6 - MMP volume change @ deployment pressure

This is the compressibility constant multiplied by the pressure at
the Deployment (Neutral) Depth (Item 5 × Deployment (Neutral)
Pressure).
7 - MMP volume @ deployment pressure

This is the calculated volume change at the planned neutral depth.
In this calculation, the volume change is subtracted from the
reference volume (Item 4
Item 6).
8 - MMP volume temperature correction constant

This is the constant characterizing the dependence of MMP volume
(density) on temperature.
9 - Temperature difference

This calculation is the temperature difference between the
reference water and the temperature at the planned neutral depth
(Item 2
Deployment (Neutral) Temperature).
10 - MMP volume change @ deployment
temperature

This calculation is the temperature constant × temperature
difference (Item 8 × Item 9).
11 - MMP volume @ deployment temp & pressure

This calculation is the temperature (and pressure) of the corrected
volume of the profiler, i.e., the volume at the neutral pressure and
temperature (Item 7
Item 10).
12 - Calculated Air Weight for Neutral MMP @
Deployment Pressure (in g)

The air weight for which the MMP will be neutrally buoyant at the
planned neutral depth, neutral volume × neutral density
(Item 11
× Deployment (Neutral) Density .
13 - Weight Difference (in g)

The difference between the required air weight and the actual air
weight is the weight of lead that must be attached as ballast for the
profiler to be neutrally buoyant at the planned mid-point depth
(Item 12
(Item A + Item D).
14 - Ballast Weight (in g)

Note that Items 15 through 19 are used only if
ballast weight adjustments are necessary after
the initial deployment.
The final calculation is the empirical correction for the remaining
uncertainty in the compressibility constant (Item 13
128 g). This
weight is the quantity of lead to be added as ballast (removed if the
quantity is negative). McLane uses an external tare weight, so the
value in Item 14, (positive), is the water
weight of lead that must be
added to the profiler. If the tare weight of lead used to sink the
profiler for the water weight measurement had been placed inside
the pressure housing, Item 14 would be the air weight of lead to
add to the lead inside the pressure housing. The lead will be
added externally.
15 - Average Motor Current Difference from
Previous Deployment (in mA)

Item 15 is the average down motor current minus the average up
motor current. This difference can be used to calculate a ballast
adjustment.
Retain the sign (+ or ) that results from this calculation for Items
16-19. A positive difference (+) indicates a light MMP (add ballast);
a negative difference (
) indicates a heavy MMP (remove ballast).
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