OETG address

POL technology history

The Proudman Oceanographic Laboratory and its predecessors have always exploited technology to provide answers to questions relating to 'the real sea'. The transit telescope and accurate clocks used at Bidston Observatory, together with the one o'clock gun, were all used to calibrate chronometers used by sea-captains during their voyages across the Atlantic. Accurate weather records, using barometers, thermometers and rain-gauges, were obtained from 1867 to about the year 2000 when the instruments were vandalised. During the 1930s, attempts were made by Dr Arthur Doodson to measure tides and currents using early mechanical instruments (see pictures below).

Favé Tide Gauge
Picture 1 shows a Favé tide gauge. The car inner-tube is compressed by the water-level above it and this changes with the tide. The resulting changes in air-pressure in the tube are monitored by the recorder in the watertight container in the centre. The whole instrument is contained within a freely-flooding drum which is the size of a dustbin.

Data Logger
Picture 2 shows the data logger for the Favé Tide Gauge. A bellows-system at the back is actuated by the changes in air-pressure within the car inner-tube. This system moves a stylus which leaves a trace on a central cylinder (not fitted): the cylinder is turned by a small electric motor driven by the Ever Ready battery and the toggle-switch in the foreground. The instrument is kept dry within a watertight case.

Picture 1 - Favé Tide Gauge	Picture 2 - Data logger	Picture 3 - Arthur Doodson with an early current meter

Picture 3 shows Arthur Doodson with an early Current Meter. The water-movements turn the large fan at the front, and the vane at the back orientates the meter with the direction of the current-flow. The picture was taken on the Zephyr (see below).

Picture 4 an early Current Meter Record. Picture 4 shows a current meter record which was probably written by a mechanical stylus onto a smoked glass slide. It is about two minutes long: note the white timing-rectangles along the bottom, showing half-minute intervals. The average current is about 0.7kt (0.36m per second): this will be due to a steady tidal current. The average current is modulated by a signal of about 15 cycles per minute: this will be caused by small surface waves with a four-second period. The record was probably obtained from just below the surface of the water and there is no indication of the direction of current-flow.

Picture 5 shows The Zephyr. This motorised ketch was about 40ft (12m) long and was owned by the University of Liverpool. It was fitted with special deck-gear and a winch below decks which were used to lift instruments into and out of the water. Arthur Doodson is seen standing near the bow.

Picture 6 shows the winch on the Zephyr. It was mounted in the hold and was turned by hand. The wire is about 8mm in diameter, but there was no scrolling mechanism to wind the wire evenly onto the winch drum. The gear-driven winch would have had a working capacity of about 100kg (220lbs).

Picture 4 - An early Current Meter Record	Picture 5 - shows The Zephyr
Picture 6 - The Winch on the Zephyr.

Picture 7 shows the Zephyr deploying a Favé Tide Gauge. The heavy gauge is the size of a dustbin, and its weight is being taken by the two men operating the large wheel at the bottom left of the picture. The wire leads back to the lifting boom on the foremast and thence to the winch in the hold which is operated by a man turning a large cranked handle. Arthur Doodson is seen at the right of the picture.

During the 1930s, tidal-prediction machines were also developed by Arthur Doodson. These became large and impressive instruments, and, with careful setting-up, could predict high and low water for years ahead (or behind). They were essentially analogue mechanical computers, and during World War II, were used to provide tidal predictions for the D-day landings. The illustration shows a Doodson-Légé tidal-prediction machine in the foyer at Bidston Observatory in about the year 2000, close to the time when the last operator who had used the machine "for real" retired. Légé was the company in London that built the machine

Picture 7 shows the Zephyr deploying a Favé Tide Gauge	Picture 8 shows a Doodson-Légé tidal-prediction machine working at Bidson Observatory

Picture 8 shows a Doodson-Légé tidal-prediction machine working at Bidson Observatory. The operator (usually a young lady, and known as a "computer") sat at the controls at the left-hand end. The tidal prediction-trace was produced on the white chart-roll at eye-level, also at the left-hand end of the machine.

Electronic computers were used to produce tidal predictions during the late 1960s, and these days predictions for the years 1066 or 3000 can be made with almost any laptop. POL has received requests for tidal predictions for many events in history.

Modern instrument-systems for use in the sea tend to contain a sensor, processing-electronics, a data recorder and a battery. Instruments of this type started to appear in the 1950s, and by the 1970s were in regular use. Thus, POL Technology used many Aanderaa current meters to measure ocean currents around the UK, and started to use sea-bed tide recorders at about the same time. Most instruments used reel-to-reel magnetic tape recorders as the data-logging medium.

During the late 1990s, POL's technical effort was spread over scientific projects - there was no formal Technology Group. This led to a degree of insularity and inflexibility - ideas did not flow freely between groups. During 2003, scientists and engineers were canvassed on the idea of a re-formation of a formal technology group. A model was devised which provided effort in the four main areas of POL engineering activity - TGI and the three sub-groups within the OETG (see the POL Technology Home page). The Technology grouping (i.e., OETG and TGI) came into formal operation when POL moved from Bidston to its present site on the campus of the University of Liverpool in December, 2004.

Eighteen engineers and technicians now serve in the OETG and the TGI. They design, produce and use cutting-edge instruments and techniques which recover marine data from many parts of the world. The need to provide warnings of tsumami and extreme surges in some parts of the world means that it is becoming necessary to get data back to POL almost as soon as they are collected. POL engineers are using and improving through-water and satellite telemetry systems to return data from many places: data co-ordination centres are then informed quickly and can issue warnings to the populations in those relevant areas.

POL Technology is also at the forefront of research into the movement of seabed sediments by currents, both tidal currents and wave-induced currents. Seabed frames, designed to interfere as little as possible with the parameters being measured, record near-bed turbulent currents and resulting sediment-resuspension. STABLE III (see picture 9) is the latest and largest of these instruments and will help to maintain POL's world-class position in these studies for many years. Picture 10 shows how clouds of seabed sediment (red and yellow colours) are pulled up off the bottom as a series of large waves passes over the instrument.

Picture 9 shows STABLE III was fully assembled for the first time in March, 2007, and here, it awaits its first deployment. It is designed so that the instrument-suite can be changed as dictated by evolving scientific requirements.	Picture 10 shows clouds of sand are lifted from the seabed by surface-waves passing overhead. Blue colours represent clear water and yellows , reds and browns represent increasing suspended sediment concentrations.