RV "KRONPRINS HAAKON": MAGNETOMETER <back to main page>

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INTRODUCTION

A magnetometer comprises towfish body where the sensor is installed, a towing system most likely assisted by a winch, and deck or instrument room based instrumentation for display and distribution of data for immediate time and position tagging.

Magnetometer towfish. This is the instrument currently in use: Model G882 manufactured by Geometrics.

Link to our magnetometer web page.

MAG WINCH CURRENTLY IN USE

Current (2015) magnetometer winch. Manufacturer: Karmøy Winch AS. Click photo to see larger version.

We have two identical magnetometer winches. The oldest was delivered in 1996, and the newest in 2009. Each winch is furnished with slip-ring box and hydraulic motor.

Specifications:

Manufacturer: Karmøy Winch AS
- Ref. Karmøy Winch drawing no. 262039. Winch has name plate with the same number on (262039).
Drum size: Dia. inner/outer: 508 / 1100 mm x drum width 600 mm.
Drum capacity: 3000 meter w/ Ø=31mm dia. cable.
Hydraulic pressure: 160 bar.
Hydraulic oil flowrate: 10 liter/minute (yields 30 meter/minute).
Force: 300 kg on inner layer.
Brake: Yes (Norwegian: "Pal bremse påmontert vinsjen".)
Winch adapted for slipring ("Vinsjen tilpasses for slepering i lager ende.")
Winch delivered sandblasted, primed and painted ("Sandblåste, metalliserte og malte.")

Winch foundation, measured on RV "G.O. SARS"

Click to open drawing (PDF format) made of "as-built" magwinch foundation on RV "G.O. SARS":

Magwinch foundation, as measured on RV "G.O. SARS". Click to open PDF document.

Mag winch foundation on RV "G.O. SARS", facing aft - click to enlarge:

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Mag winch foundation, on R/V "G.O SARS" (click to enlarge).

Winch foundation, manufacturer's drawing

Detail from Karmøy Winch drawing no.: M361804.DWG

Winch photos, 22 March 2010

Click to see large images.

Mag winch slipring box

The Geometrics G-882 has a 5-conductor tow cable with layout as shown below (excerpt from page 108 of G-882 Manual).

Power lines have max 32 Vdc, 0.75 Amp at start-up and 0.5 Amp thereafter. RX/TX are low voltage/current signal lines.

Geometrics G-882 Magnetometer tow cable layout (excerpt from page 108 of G-882 Manual)

FUTURE GRADIOMETER

Background

Ref:

New vector gradient magnetometer used successfully for the first time, by Federal Institute for Geosciences and Natural Resources, Germany

Report, R/V "Sonne", Cruise no.: SO-180

Quoting from ...file: EGU06-J-02680.pdf:

The development of towed marine magnetometers has led to point where few wishes remain open as far as total field measurements are concerned. Equipped with state-ofthe-art Overhauser sensors these magnetometers are relatively inexpensive, reliable, easy to handle and they can be combined to work as gradiometers. However, in many cases it is desirable not only to know the scalar value of the total field but also to have access to the magnetic field’s vector components. This opens a wealth of possibilities in analysis and modelling, especially in regions where the total field anomalies have low amplitudes. These facts led to the development of a new towed marine vector magnetometer using three orthogonally oriented Fluxgate sensors in our group at the Federal Institute for Geosciences and Natural Resources (BGR).

The new magnetometer was successfully tested during cruise SONNE-180 ....

Manufacturers

Geometrics (G-882 Marine Mag in gradiometer config)
Marine Magnetics