Working in physics: Of time and tide

For Stephen Taylor, running a marine-software company means plenty of chances to apply familiar physics to unusual real-world problems – and being your own boss is nice too.

Steering his own course

We often hear of physicists trying to understand, map and explore objects in outer space, but there are also big opportunities for physicists where inner space is concerned. This is particularly the case with the world's oceans. For example, while the study of tides dates back thousands of years and was regarded as a dead subject for most of the last century, we now realize that tidal physics has an unexpected environmental dimension. Applications of this revitalized science range from the siting of tidal power generators and the optimization of fuel-saving shipping routes, to the effects of tidal height on flood defences and satellite-based measurements of sea level.

This is where firms like mine, Geomatix, come in. Recent Geomatix projects include improving the accuracy of tidal predictions in the Thames Estuary for the Port of London Authority, estimating the mean sea level for surveyors in the Persian Gulf, and providing electronic charts of the sea bed for the fishing industry. The work extends across the related fields of cartography, hydrography, oceanography and geodesy – all areas where physicists are ideally suited for tasks ranging from instrumentation to surveys and mathematical modelling.

A long road to the sea
My career would not have been the same without my first physics teacher, the Reverend Brother Egbert. A rather eccentric individual, he would often announce things like "the whole of physics is oscillatory" at seemingly random intervals. On one occasion he sprayed his students with a Bunsen burner connected to a water tap. This may seem like an unlikely inspiration to study physics, yet I credit him, and my father, an early radio ham, for setting me on a career path that led – after many twists and turns – to me becoming my own boss at Geomatix.

I graduated with a physics degree from Nottingham University in 1975 and then worked for the UK's Water Research Centre for some years before the tedium of government research drove me to back to academia. In 1984 I obtained a PhD in applied physics from the University of Hull, specializing in laser remote sensing. My experience with infrared-laser radar systems then took me to the US, where I joined RCA Astro Electronics, which is now part of the defence giant Lockheed Martin.

At RCA I was expected to work on military space projects involving optical communications. But when I attended a meeting where some military guys dispassionately discussed how using infrared optical communications, rather than radio, could be a great benefit during a nuclear war in CONUS (military speak for the continental US), I was disgusted by their callous attitude. I realized that a career in military research was not for me. I therefore left RCA and returned to the UK to become a senior lecturer at Humberside Polytechnic's department of maritime operations, specializing in navigation and radar-simulation training.

Unfortunately, the department closed shortly after I joined it, and in the ensuing chaos I was asked to work as a consultant. At Humberside I had been involved in the design of marine-radar training simulators, and one of our research sponsors asked me to design a similar system for them. This was my lucky break. Before then, the people who paid me were my bosses; now they were magically transformed into my clients. I was able to use my skills in electronics, computing and design to rapidly produce a system that fitted the bill. I was also able to set my own direction and targets. Within a year I had produced AutoTide, the world's first tidal-prediction system compatible with the then-new Microsoft Windows operating system. I was enjoying being my own boss.

Branching out
I started the company now known as Geomatix in 1992 as a one-man operation with the goal of selling AutoTide in the marine market, but I soon moved into other areas – notably marine mapping – via a contract with the UK's Sea Fish Authority in Hull. The growth of oil and gas production in the North Sea had caused problems for the local fishing industry, as trawl gear would sometimes get caught on sub-sea installations. This led to some nasty accidents and even fatalities, so I became involved in converting sea-bed data about oil and gas installations into electronic marine charts for fishing vessels, so that they can avoid hazards while trawling.

As part of this work, I spent one summer frantically driving around harbours and intercepting fishing vessels so I could test the then comparatively new GPS-based electronic charts. On one occasion, I almost ended up marooned on a fishing vessel as it was forced to leave harbour by the descending tide. This could have been an embarrassing error for someone in the business of tide prediction – especially since the vessel was going to be at sea for two weeks – but fortunately I was able to persuade the skipper to drop me off as we passed the outer pier in Scarborough harbour.

The business started to expand in the early 2000s, allowing me to hire a business administrator and a programmer with an MSc in astronomy. In 2003 we decided to concentrate on the specialist area of harmonic tidal analysis. This is like a first cousin of Fourier analysis, and it enables you to work out the transfer function between the tidal potential and the instantaneous tidal height. It also provides highly accurate figures for mean sea level. So far, our systems for tidal harmonic analysis have been used in more than 30 hydrographic offices for tidal prediction and by numerous hydrographic surveyors to determine sea level. Given the threat of climate change and its associated predicted rise in sea level, systems like ours are a useful tool for examining recent trends. The good news is that even with our advanced analysis software, any rise in sea level is almost entirely masked by noise on the tide gauge data from storms and surges – so far.

Real-world physics
In this industry, it is not unusual to find physicists (many with their own businesses) working amongst hydrographers, mariners and oceanographers. Hydrographic topics like map projections, navigation and data analysis figure high on the list of requirements, and all use very similar mathematical skills to those required in physics.

For example, the physics problems associated with tidal prediction are actually quite similar to those of infrared spectroscopy. Both techniques deal with issues like resolution, line width and modulation – it is just a matter of changing the frequency band from infrared spectral lines at about 1013 Hz to tidal "spectral lines", or constituents, of about 10–7 Hz. The strongest tidal constituent comes from the semidiurnal (twice-daily) tide and has a frequency of 2×10–5 Hz. In long-duration datasets of tidal height, in contrast, significant tidal components can be resolved down to events that occur about once every 18 years, or 10–9 Hz – a frequency in line with theoretical models based on the known orbital parameters of the Sun-Moon-Earth system.

Just as in the field of non-linear optics, non-linear effects generate additional frequency components, producing for example the phenomenon of standing tides that are found on parts of the UK's south coast. In this field, at least, Reverend Brother Egbert's phrase about all physics being oscillatory is pretty much spot-on.

On a day-to-day basis, my job as head of a small-marine software firm involves some programming and some sales work, as well as speaking to mariners, port hydrographers and representatives from the oil and fishing industries. Recently I have also presented a few papers at hydrographic and oceanography conferences, but I am not obliged to churn out publications to meet some bureaucratic university target, and am unfettered by internal politics. Instead, I have the freedom to use the skills I gained as a physicist to benefit clients in the wider world, where I have found there is a great need for the practical application of physics and which can be outstandingly rewarding.

About the author
Stephen Taylor is managing director of Geomatix Ltd, email set@geomatix.net.


This article originally appeared in the October 2009 issue of Physics World

last edited: December 04, 2014



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Working in physics

Of time and tide