For those unfamiliar with drillships, the new ones are built from super tanker hull designs with one noticeable change… they cut a large hole in the middle of the ship above which they erect a drilling derrick. This large hole is called a moonpool.
About 4 years ago I was working aboard a large exploratory drillship in the Gulf of Mexico and we ran into a problem; a hammerhead shark was found swimming around our moonpool and we had no way of getting it out alive.
We tried everything from slowly lowering bait, down in the hopes the shark would swim down and out of the moonpool, to gently prodding it that direction. Nothing worked. Then, after about a week of false hope, a new electronics technician arrived and suggested our problem was related to the ships magnetic degaussing system, a system which engulfs the ship in an electrical current to inhibit corrosion. He suggested the shark used electromagnetic signals to navigate and our system was confusing the predator. With nothing to lose we disabled the degaussing system and immediately the shark swam towards freedom.
One company, Oak Ridge Shark Lab of the Bahamas, has taken the theory of confusing sharks with the use of magnets to the next level with a new product from their subsidiary Ocean Magnetics. With the use of rare-earth materials such as neodymium and boron, and combined with iron, the company has developed a line of products from magnetic jewelry to magnetic fish hooks that repel most species of sharks.
For their work in 2007, the company was awarded the WWF’s SmartGear award, issued to product with the most potential for reducing fisherman’s bycatch of unwanted fish species.
But Ocean Magnetics didn’t stop there…
Instead they continued their research and successfully developed electrochemical shark repellents and later highly effective natural deterrents which appear to show a great deal of promise when applied to man overboard scenarios in shark infested waters.
Magnets are clearly effective at repelling sharks, however they are heavy, highly susceptible to corrosion, work at limited range, and thus impractical for use in a MOB scenario. Oak Ridge Shark Lab’s natural deterrent – a concentrated liquid sold under the name SharkDefense – is lightweight, heavily concentrated, and deployable by a wide range of methods from toy water guns to pneumatic air grenades and hydrostaticly deployed cylinders.
In developing SharkDefense the scientists first got the idea by talking to fishermen and discovered that some would tie dead shark carcases to the back of their boats to deter sharks. Using this idea the scientists distilled a concentrated perfume from rotting shark remains – creating a odiferous substance which sharks hate.
And it works! In tests, deployment of just a few ounces of the substance made all sharks in the area immediately disappear. Don’t’ believe us? Well take a look at this video produced by Mike Rowe of the Discovery Channel show Dirty Jobs:
The only question left for mariners is when will this substance be standard equipment in all lifeboats and abandon ship ditch bags.
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