Bumpy edges could be key to record-breaking oars | Science News for Students

Bumpy edges could be key to record-breaking oars

Innovative design was inspired by a whale’s flippers
May 20, 2019 — 1:01 pm EST
Lucy Lake holds her bumpy rower's oar design at Intel ISEF 2019

Lucy Lake, an 18-year-old 12th-grader from Sydney, Australia, shows off her design for a better rower’s oar. Its scalloped edges were inspired by the bumpy flippers of humpback whales.

C. Ayers Photography/SSP

PHOENIX, Ariz. — World-class rowers could someday shatter records for speed using oars whose design is based in part on a whale’s flippers.

Just ask athletes from any sport: World records aren’t easy to break. Sometimes a new way of training helps athletes gain an edge. But other times, new technology lends a hand, notes Lucy Lake. This 18-year-old rower attends Barker College in Sydney, Australia. And she knows more than a little about the history of her sport. Technology really helped rowers break speed records decades ago, she explains. Now she’s come up with an advance that she hopes may propel future rowers to shatter today’s records.

Rowing races typically cover a distance of 2 kilometers (1.24 miles). In 1952, says Lucy, the world record for rowing that distance was 8 minutes, 12 seconds. Back then, rowers used oars made of wood. But in the decades that followed, rowers started using oars made from lighter materials, including plastics. By 1988, the world-record time for rowing 2 kilometers had dropped to 6 minutes, 49 seconds. And since then, Lucy notes, not much progress has been made. The current record, set in 2016, is only 8 seconds faster than the record set 31 years ago.

It’s time for a new phase of oar evolution, Lucy says. To come up with a new oar design, she used computer software that analyzed the flow of water around objects. The sizeable bumps, or tubercles, along the front edges of a humpback whale’s flippers served as her inspiration.

On an oar blade, those bumps help a rower in several ways, Lucy’s science-fair research now shows.

a photo of a humpback whale fin sticking out of the water
A humpback whale shows off the bumps, or tubercles, on the front edge of its flippers. Those bumps may give it better thrust as it moves through the water.
davidhoffmannphotography/iStock/Getty Images Plus

First, those bumps help keep water that flows around the oar’s blade from breaking away from the blade as quickly as it would if the edges had been smooth. (That sort of breakaway is the same thing that happens when an aircraft wing stalls. A stall, in turn, causes a loss of the lift needed to keep a plane aloft.) So, in the first part of a rower’s stroke, bumpy-edged oar blades provide more power.

During the middle part of a rower’s stroke, an oar blade with bumpy edges creates less turbulence than a smooth-edged oar. Less turbulence means less drag — and thus more forward thrust, explains Lucy.

The final benefit comes when the rower removes oars from the water and brings them forward to begin the next stroke. During this phase, a bumpy-edged oar blade reduces how much drag the blade encounters as it moves through the air. Because air resistance is typically low, this provides only a small benefit, Lucy admits. But when a world record is on the line, she adds, every little bit helps.

Lucy showcased her new oar design here, last week, at the Intel International Science and Engineering Fair. This competition was created in 1950 by Society for Science & the Public. The 2019 event, sponsored by Intel, brought together more than 1,800 finalists from 80 countries. (The Society also publishes Science News for Students.)

Besides using computer software, Lucy field-tested her design. First, she made prototypes of smooth-edged and bumpy-edged oar blades. Then, she came up with oar handles that would fit both types of blades. This let her swap them out and test each type of blade without changing the length of the oar or the weight and feel of its handle.

On several days, she tested one type of oar blade, and then the other, over a distance of 500 meters (or almost 550 yards). During each test, she rowed, rowed, rowed her boat at 20 strokes per minute. That’s a common rate, she points out.

On average, Lucy finished the course 3.6 seconds faster when she used the bumpy-edged oar blades. If a world-class rower were able to do the same — and keep up the pace for a full 2 kilometers — they might be able to break the world record by as much as 14.4 seconds, she estimates.

Power Words

(more about Power Words)

average     (in science) A term for the arithmetic mean, which is the sum of a group of numbers that is then divided by the size of the group.

current     A fluid — such as of water or air — that moves in a recognizable direction. (in electricity) The flow of electricity or the amount of charge moving through some material over a particular period of time.

drag     A slowing force exerted by air or other fluid surrounding a moving object.

engineering     The field of research that uses math and science to solve practical problems.

evolution     (v. to evolve) A process by which species undergo changes over time, usually through genetic variation and natural selection. These changes usually result in a new type of organism better suited for its environment than the earlier type. The newer type is not necessarily more “advanced,” just better adapted to the particular conditions in which it developed. Or the term can refer to changes that occur as some natural progression within the non-living world (such as computer chips evolving to smaller devices which operate at an ever faster speed).

field     A term to describe a real-world environment in which some research is conducted, such as at sea, in a forest, on a mountaintop or on a city street. It is the opposite of an artificial setting, such as a research laboratory.

humpback     A species of baleen whale (Megaptera novaeangliae), perhaps best known for its novel “songs” that travel great distances underwater. Huge animals, they can grow up to more than 15 meters (or around 50 feet) long and weigh more than 35 metric tons.

Intel International Science and Engineering Fair (Intel ISEF)     Initially launched in 1950, this competition is one of three created (and still run) by the Society for Science & the Public. Each year now, approximately 1,800 high school students from more than 80 countries, regions, and territories are awarded the opportunity to showcase their independent research at Intel ISEF and compete for an average of almost $5 million in prizes. 

lift     An upward force on an object. It may occur when an object (such as a balloon) is filled with a gas that weighs less than air; it can also result when a low-pressure area occurs above an object (such as an airplane wing).

prototype     A first or early model of some device, system or product that still needs to be perfected.

resistance     (in physics) Something that keeps a physical material (such as a block of wood, flow of water or air) from moving freely, usually because it provides friction to impede its motion.

software     The mathematical instructions that direct a computer’s hardware, including its processor, to perform certain operations.

technology     The application of scientific knowledge for practical purposes, especially in industry — or the devices, processes and systems that result from those efforts.

thrust     A force that makes an object move forward.

tubercle     A tiny knobby projection — a prominent bump — that occurs naturally on some part of a plant or animal. It might be a protruding nodule on a bone or the surface of the skin, for instance.

turbulence     The chaotic, swirling flow of air. Airplanes that run into turbulence high above ground can give passengers a bumpy ride.

whale     A common, but fairly imprecise, term for a class of large mammals that lives in the ocean. This group includes dolphins and porpoises.