Kristian Tonder

Seismograph Service Ltd.
Holwood, Keston, Kent, England

North Sea - 1969

Seismic source: Propane-Oxygen Sleeve Exploders

Data acquisition system: Texas Instruments DFS-III

Navigation system: Decca Navigator Mk-12


Cable Drum holding the wound-up hydrophone (streamer) cable & lead-in cable with it's "dead-sections".
The Tail-buoy has a radar reflector so that the "feathering angle" of the streamer cable can be measured
on the radar set at night. It was also measured visually in daylight using a horizontal Theodolite.


Another type of tail buoy - which incorporated a flashing light for night-time visual location.


The bank of cylinders of compressed propane


Another view of the bank of cylinders of compressed propane.
A sleeve exploder can be seen on the deck.

Enlarged view of the Propane-Oxygen Sleeve Exploder.


Helicopter arriving to collect a box of recorded magnetic data tapes -
for urgent transport to the computer processing centre.


The helicopter lowers a cable (while trying to avoid colliding with the ship's masts) -
and the box of magnetic tapes is attached.


The helicopter moves away quickly out of danger - still dangling the tapes.


The Instrument Room. The Texas Instruments DFS-III digital data acquisition & recording system can be seen
mounted on the walls for convenient operation, calibration & servicing.


Supplies of spare parts, streamer-cable sections (to replace damaged sections) and food
are brought alongside & the hard job of getting them on board (up and over the side) begins.


Coming into port.


Rough seas as the ship enters the shelter of the harbour.

Decca Navigator Mk-12

(Received 3 signals or lanes from shore stations - Red, Green, Purple)


(Photos - Robert J. Horne)