Sleep engineering offshore

In the last two decades, the technological improvements in modern offshore racing craft have been astounding. These boats are lighter, faster, and stronger and carry towering rigs. About the only element of ocean racing that hasn’t been re-engineered by modern technology is the humans that race them.

Until now.

By making use of microprocessor sensors on board race boats, researchers like Dr. Claudio Stampi, director of the Chronobiology Research Institute in Newton, Mass., are able to monitor the sleep behavior of racers. Once they have gathered enough data to map an individual’s sleep profile, Stampi and his colleagues can show a racer how to fine-tune his or her sleep behavior. “Our job is to help them understand their sleep tendencies,” said Stampi. “For each person the nap patterns are different.” When racers know their pattern, they can get refreshing sleep and be more alert when they are awake.

One ocean racer who has used Dr. Stampi’s services with success is Ellen MacArthur, the recent winner of the monohull division of the singlehanded transatlantic race the Europe1 NewManStar. MacArthur, who raced aboard her Open 60 Kingfisher, wore a wristwatch-sized device called an Actiwatch throughout the race. It measured her wake time vs. sleep time and relayed the results via satellite to Dr. Stampi at CRI. MacArthur’s sleep patterns were also posted on her Kingfisher web site ( for all the world to see. The Actiwatch, manufactured by Mini Mitter Co. of Sunriver, Ore., contains a piezoelectric accelerometer that measures movement by taking advantage of something called the piezoelectric effect (squeezing certain types of crystals creates a tiny but discernible electric voltage). Inside the accelerometer unit, a lever arm rests on the crystal. Movement causes the arm to press down on the crystal and produce a voltage. A microprocessor in the Actiwatch records this voltage, translates it into movement, notes the time, and then stores the result in RAM. From this movement record it’s possible to determine when a user is awake and moving around and when he or she is asleep and lying (relatively) motionless. The Actiwatch device is used for a variety of studies when the subjects under scrutiny are land-based. In MacArthur’s case, and in any study involving sailors, there was an added factor for researchers to take into account: the motion of the boat in the waves. They solved this problem of spurious sensor motion by placing a second sensor inside the boat. This Actiwatch only measured the motion of Kingfisher. By subtracting the boat-only data from MacArthur’s combined motion data, they canceled out the boat motion effect and were left with data that revealed only MacArthur’s motion.

To get the data stored in the Actiwatch back to Dr. Stampi at CRI outside Boston, MacArthur slipped off the watch and placed it on the Actiwatch reader unit once a day. Inside the Actiwatch unit is a low-strength FM radio transmitter. In order for the reader unit to pick up the Actiwatch’s signal, the watch must be within four or five millimeters. The watch downloads the latest set of motion data, and the reader sends it on to the boat’s Inmarsat C satellite transceiver. From there the motion data file is sent via Inmarsat C and the Internet to CRI. This data-delivery method allowed Dr. Stampi to monitor MacArthur’s sleep cycles in nearly real time. During the race MacArthur slept an average of four hours and 11 minutes per day. But she never slept more than 80 minutes at a time, and some of her sleep periods lasted no more than seven minutes. Her sleep periods fell into two categories: uninterrupted naps, usually lasting less than 55 minutes, and nap clusters, in which longer sleep is broken into 15- to 30-minute blocks. MacArthur would wake up between naps, check the weather and the boat for three to eight minutes, and then go back to sleep for another nap. These nap clusters accounted for 37% of her total sleep during the race.

Clearly, the key to this approach is effective use of the catnap. “Ideally you want to take short naps, but they have to work for you,” said Stampi. “A combination of long and short naps works best.” Singlehanded racers must learn to balance the pressures of racing and keeping an eye out for other vessels on one hand with the their body’s need for sleep on the other.

MacArthur began using Dr. Stampi’s services about eight months ago. Stampi began with a basic course on sleep and alertness. “Then she went out [sailing] and paid attention to her sleep patterns,” said Stampi. “Gradually she became aware of which sleep strategy worked and what didn’t.” A big test of MacArthur’s ability to put Stampi’s teaching into practice came during her delivery of Kingfisher from its New Zealand building yard home to Britain in March. MacArthur proved to be a quick learner. “She is very determined and very eager to learn,” said Stampi. “She has done a good job.”fatigue management services to the 1998 ?’99 Around Alone racers. In that race, the whole concept of sleep takes on a new meaning when the competitors reach the Southern Ocean. In that maelstrom of howling wind and massive waves where you might be surfing at 20 knots, it requires steely nerves to leave the boat to the autopilot and go to sleep.

Stampi has circumnavigated himself and understands the issues. “It is not easy,” admits Stampi. “The boats are light, and they vibrate. It requires that the racers have confidence in the boat and in themselves.” According to Stampi, the best ocean racers develop the peculiar skill of sleeping while still keeping part of their brain listening to the sounds of the boat. If something changes, they tend to wake up immediately and deal with it.

Stampi plans to expand and eventually offer this type of service to more than racers. Voyagers headed into more extreme situations, for example, might want some sort of sleep and alertness training and input. “We could monitor each person in the crew,” said Stampi. “And we could inform the captain of those crewmembers who are getting dangerously fatigued and provide recommendations for sleep.” Likening his service to weather routing, Stampi calls it alertness routing.

Since many voyagers go offshore to escape civilization, one wonders whether they will want to be remotely monitored while on a passage. While this kind of service may be considered invasive by some, voyagers eager to have the latest technology possible will, no doubt, take full advantage of CRI’s proposed service.

By Ocean Navigator