Navy Developing Submarine Based on Boxfish

P O R T L A N D,  M A I N E,  July 30, 2001 -- The tiny boxfish looks like a cartooncharacter with its peculiar shoebox shape and bright yellow bodywith black spots. It lives in a rigid shell, unable to bend itsbody because its scales are fused together.

It seems an unlikely candidate for military research, but thistiny wonder is the very model the U.S. Navy hopes to use to designa new miniature submarine that will scour the ocean bottom,operating efficiently even in turbulent waters.

The sub could have myriad uses, whether to comb for underwatermines, conduct scientific research or hunt for wreckage fromairplane crashes.

"Fish are phenomenally maneuverable compared to anything thatis man-made," said Jeff Walker, a biology professor at theUniversity of Southern Maine who is studying the boxfish to betterunderstand how it swims and moves its body.

"It's a lofty goal for a human-made vehicle to achieve theperformance of a fish."

Creating a Boxfish Machine

The Office of Naval Research awarded Walker a three-year $90,000grant to work with a team of engineers on the project. The NavalUndersea Warfare Center in Newport, R.I., will be in charge ofdesigning the sub, also known as an "autonomous underwatervehicle," or AUV.

The AUV should be able to remain stable while working in watersshallower than 1,000 meters, said Robert Gisiner, who is overseeingthe project at the Office of Naval Research. Existing AUVs, hesaid, are not good at handling underwater currents greater than 1knot.

"What we're interested in creating is an underwater [machine]that has the abilities of a biological organism that you can't getin standard structures now," Gisiner said.

The boxfish is related to the better-known puffer fish and livesprimarily in tropical waters around coral reefs in the PacificOcean.

Working in a cramped laboratory at the University of SouthernMaine, Walker is studying three juvenile boxfish that he has namedKing Kong, Nessie and Jaws. A high-speed digital camera recordstheir activities and downloads the images onto a computer, wherethe movements and speed can be precisely measured.

The boxfish is no bigger than a couple of matchboxes stacked oneon top the other. But it is a perfect research specimen because itis so maneuverable and can turn on a dime, almost like it isrotating on an axis.

Boxfish fins look like folding fans and act as paddles. Bypaddling one of its pectoral fins forward and the other backward,the fish can make a 360-degree turn with barely any movement — justlike a person in a stationary rowboat paddling the oars indifferent directions to turn around.

"The turning radius of this fish is essentially zero," Walkersaid.

Also Available: 'RoboTuna,' 'RoboBass'

Walker is chronicling the fish's exact turning radius and thespeed at which it turns around. Later, he will determine theusefulness of the fins on the top and bottom of its body. Afterall, there would be no need to include top and bottom fins on anunderwater vehicle if they serve no useful function.

He will also place the fish in a wave tank and determine how itacts in turbulent waters.

Walker isn't the first scientist to study fish locomotion tofurther the design of unmanned submarines. "RoboTuna" is anunderwater vehicle whose tail is designed after the tail of abluefin tuna. "RoboBass" has fins on its side that are modeledafter the fins of a small-mouthed bass.

Nobody has given a name to the machine that will be built basedon the boxfish. Whatever the result, Walker's work illustrates therelationship between biology and engineering.

"It's an odd connection between biologists and engineers,"Walker said. "But I think it's a fruitful one."