John Potter – IEEE Fellow, OES AdCom, Dist. Lecturer and Chair, Norway Chapter, Assoc. Ed. JOE.
So the famous children’s story goes, enticing generations of young minds to stretch their imagination to the horizon, to take on the challenges of travel, change, and excitement that comes with an uncertain leap into the wide blue ocean, where the horizon changes hour by hour, day by day. An old-fashioned romantic dream, perhaps? Overtaken by the cumbersome realities and financial burdens of big research vessels, operated by professional crews? But what if I told you that this kind of dream has now come full circle, in this age of miniaturised and low-cost oceanographic sensing systems, with all that the romantic vision offers and more?
I am talking about a game-changer in ocean scientific research. No, not about how robotics and autonomous vehicles will change the face of ocean data collection (although they have, and will continue to do so in even greater measure). I’m talking about the next wave, smaller perhaps, but with an important niche that fits between the ‘traditional’ research vessel and the un-crewed autonomous or remotely-operated platform. Sailing boats.
Why sail, you ask? Well, because in order to reach thousands of miles offshore, to remote and inhospitable places without the infrastructure to refuel a motor vessel, an engine-driven research ship has to carry enough of its own fuel for the entire trip. That needs a bigger boat. Which burns more fuel, which needs larger tanks, which needs an even bigger boat. Fortunately, this version of Zeno’s paradox converges, essentially because the mechanical power required to push a vessel’s hull through the water increases as the square of its length, whereas its capacity to carry fuel increases as the cube of its length. But it means that for offshore work, a motor vessel must be at least ~50m to be capable of operating anywhere in the world. And this is fine, if you can afford it and need to carry large equipment, with heavy winches to lift it, or need a sizeable scientific team. But you must find the $10,000 – $20,000 a day that such a vessel demands in operating expenses. A sea trial of 20 days (and remember, it can take a week to get wherever you are going and a week to get back) might then require more than a quarter of a million dollars, before you even set foot on the gangway.
But a sailboat, with solar power, a watermaker and modern navigational electronics, is quite a different proposition. A sailboat, being wind-powered, does not need to carry vast amounts of fuel. With modern wind and solar energy conversion systems, a small auxiliary generator, and a watermaker, an ~18m sailboat can be both completely seaworthy and support a scientific crew of perhaps 6 for up to 3 months without resupply.
Contrary to common thinking, a vessel does not have to be large to be seaworthy, even in the most savage storms. An empty wine bottle, well-corked, may survive the most powerful hurricane, while a super-tanker may not. OK, so it would not be a comfortable experience (even if, like Alice after eating her cake, you could fit inside) but you would survive. Even the uncertainty of heavy weather is now much reduced with affordable Iridium satellite connectivity, providing telephone, email and custom weather forecasts derived from the most sophisticated ocean-atmosphere models now available, lending considerable confidence to route planning and safety. Smaller boats also bring some advantages, being able to enter more restricted passages and navigate in shallower waters than their larger sisters.
And here is the punchline. An 18m sailboat, well founded and equipped with modern navigational aids and facilities comparable with many ‘small’ research vessels, probably costs only 10% of a ‘traditional’ research vessel. Suddenly, a sea trial that might have cost half a million dollars could perhaps be organized for $50k. So why are we not seeing many more sailboats out doing research?
Firstly, this is a niche market. It only works if the number on the research team can be kept small, if there is no need for large and heavy equipment, and if the researchers are comfortable on a small vessel. Secondly, the size, weight, cost and power requirements of sophisticated ocean research equipment, everything from side-scan sonars to rugged laptops, has only recently come down to the point where it becomes possible to economically host genuinely top-notch research efforts from a small platform. Take the watermaker, for example. The last couple of decades have seen great improvements with the advent of energy recovery systems and membrane technologies, so that reverse osmosis desalination of substantial quantities of water are now within reach of a sailboat electrical power budget. A litre of pure drinking water can now be squeezed out of seawater for < 18kJ. Thirdly, you need a compact crew that has a very broad range of skills. Once out of sight of land, the crew must be able to fix anything that goes wrong, or do without it. In addition to redundant critical systems and spares, you need good sailors first and foremost, but also a sailmaker, carpenter, electrician, plumber, mechanical engineer, diesel mechanic, electronic engineer and of course a cook, plus someone who knows how to make a mean gin and tonic for sundowners.
And so to my example. In the last issue of the Beacon, I covered the ‘rescue’ of ‘Jocara’ from the rat-infested dungeons of a dilapidated and rapidly deteriorating marina in the south of Malaysia, where her innards had been eaten out by a team of special forces rats, intent on sinking her before she could host an expedition to the Indian Ocean. In that article I said that we were interested in discovering if ancient mariners had wrecked upon the treacherous shores of this vast archipelago of reefs and islands, but that we were not going searching for wrecks, but for rats. We found both.
Allow me to explain. It all starts with a brilliant marine archeologist by the name of Bridget Buxton, who is a Professor at University of Rhode Island. Bridget has had a dream for the past decade; to search the Chagos Archipelago for evidence of ancient wrecks. For if ancient mariners had discovered the conveyor-belt-like oscillating winds and currents of the two opposing monsoon seasons in the Indian Ocean, they could have been circumnavigating that great expanse before the invention of rigs that can sail upwind. And if, as she suspected, they did not hug the coast, but boldly struck out across the core of the Indian Ocean, then some, perhaps many, would inevitably have ‘discovered’ the Chagos Archipelago by unexpectedly wrecking on it. But these ships would have been of wood, of course, which splinters and decays and may be quickly buried in shifting sand or carried away to the waiting deep. So where to look, among the thousands of square kilometers of this massive archipelago? The place to look is not for big pieces of wood or hefty iron anchors, but for little pieces of DNA.
With the cost of DNA sequencing now so affordable, it has become possible, and very smart, to look for evidence in the descendants of the survivors of these wrecks. Not human survivors, for they often did not, but rats. As in deserting the sinking ship. Given that rats are not indigenous and cannot swim large distances, the current rat populations on the various islands will bear the indelible thumbprint of their ancestors, and hence from where they came. So what we were after was rat DNA, from as many distinct islands as we could manage to sample.
And then suddenly, with Jocara available ‘only’ 1,500 n.m. away in Malaysia (and Jocara has already visited the Chagos Archipelago, in 2005) at a fraction of the cost of a ‘regular’ research vessel, perhaps this dream could finally be realised.
But this was not all. We were also after DNA from the entire marine ecosystem, to test the diversity and health of the reefs and shallows. This was inspired by a recent Nature paper (Graham et. al., 2018) which established that where there are rats, not only are there fewer birds (impoverishing the diversity of the terrestrial biome) but that this also impacts the marine environment, which benefits from the nutrients washed into the sea from bird guano. The whole island ecosystem, on land and in the sea, is inextricably linked and interdependent. Well, there’s a surprise. Who could have known?
But how does one go about sampling the marine species diversity? Traditionally, this might be done by extensive visual sampling, identification and counting over weeks and months. Hundreds of hours on scuba and snorkel, supplemented by traps and physical sediment sampling. But now, with the advent of environmental DNA (eDNA), there is an easier way to understand some aspects of the biodiversity. ‘All’ one has to do is pump a few litres of seawater through a filter, inject a stabilizer, pop it in the fridge and, once home, sequence the DNA to reveal some of the things that swam, crawled, hopped or squirmed in and around that piece of water in the preceding days.
But there’s more. DNA takes very little space, even on a ‘small’ sailboat. So we also took an underwater metal detector. And we took a top-of-the-line Overhauser magnetometer, an order of magnitude more sensitive that traditional proton magnetometers and requiring a fraction of the energy (allowing lighter-weight batteries for portable units) with faster sampling. Just for good measure, we had a high-frequency forward-looking acoustic imaging sonar, a compact sidescan and a dipping hydrophone with portable recorder. All of these instruments were so small and required so little power, they could be mounted on a cheap plastic unsinkable kayak, complete with cables, batteries, laptop and all, and towed by our dinghy or another kayak.
So it was that our little band of five crew were able to voyage over 1,500 n.m. round-trip on a 30-day expedition from the Maldives to the farthest reaches of the Chagos Archipelago, without the need to interact with a single external soul on the entire trip, provisioned and fueled to conduct several leading-edge research programmes across a dozen island groups scattered across the archipelago. We were able to collect rat DNA from every targeted island group, and took repeat eDNA samples at eleven of the twelve sites analysed in the original Nature paper, providing an invaluable opportunity to confirm their findings and explore how the islands have evolved since the first samples were taken. We were also able to discover several actual wrecks (albeit rather recent) and re-discover an ancient anchor, which was first sighted almost 50 years ago, before GPS, and which as far as we know, has not been located and documented until now.
Of course, there was also a good deal of messing about in boats.
Graham, N.A.J., Wilson, S.K., Carr, P. et al. “Seabirds enhance coral reef productivity and functioning in the absence of invasive rats”. Nature 559, 250–253, 2018.