After sliding a piece of foam under her stomach, Annie Borland lies face-down on a metal frame and begins to kick a makeshift pedaling device.
“A little bit of hip elevation helps a lot,” she says, explaining the foam.
As her team designs Cal Poly’s first human-powered submarine, Borland, the project’s life support system lead, wants to make sure it’s comfortable for the person who will be operating it. At the same time, the aerospace engineering student wants it to be as efficient as possible – because the team expects this sub to break a world record during an international race next summer.
“We have to minimize the volume as much as possible to minimize the drag,” said Rylie Bryant, the project manager for the team, named BioSub.
A few months ago, Bryant had arrived early at Assistant Professor Graham Doig’s lab and discussed her interest in biomimicry – creating something that imitates what animals do in nature. Then Doig mentioned his interest in creating a submarine that captured the swimming prowess of a leopard seal.
Doig had once worked at a zoo in Australia, where he spent considerable time observing a leopard seal in action.
“I was watching it, thinking, ‘How is it producing so much thrust?’” he said.
By the end of their discussion, Bryant, another aerospace student, decided she would pursue Doig’s idea for a human-powered submarine. Once she recruited a team, she set a goal – to compete in the International Submarine Races, held in June at the Carderock Naval Warfare Center in Maryland.
“We decided to do a race because it’s a good hard deadline to motivate us to get this done,” she said. “And it’s a good benchmark: There’s a set record to beat.”
With a goal in place, Bryant researched how sea creatures swim. While the leopard seal is an amazingly adept swimmer, it uses two fins to create that speed, which would be almost impossible to mimic. So Bryant researched other fast swimmers that would have a body shape they could replicate as a sub.
“As I continued my research, the short fin mako shark had the most optimized geometry to be able to fit a person inside,” she said.
Doig, who has built solar-powered cars in the past, has been advising the team on hydrodynamic design and project management. And he has integrated the project into the Prototype Vehicles Laboratory lab he started. While Bryant built a team to fund, design and build the project, one obvious question remained: Who would actually get in it?
“We were, like, ‘Hey – does anyone have any friends who are small, good at swimming, good at biking and not afraid to be in confined spaces?’”
Mechanical engineering graduate student Cullen Goss was a perfect fit.
“It kind of sounded fake at first,” said Goss, who heard about it through a friend. “I mean, who’s ever heard of a human powered submarine? So the chance to do something that crazy appealed to me.”
A member of the triathlon team, Goss is an avid bicyclist who liked the idea of trying to set a world record.
But while the sub will be powered by pedals, the vehicle is different than a bike. The sub’s tail will be made of natural gum rubber, so it can oscillate back and forth, like a mako shark. Meanwhile, the body will be made of a carbon fiber shell, similar to material used for a lightweight aircraft. It will be enclosed, but there won’t be much body for Goss to squeeze into.
“We’re completely fitting the entire submarine to his body,” Bryant said.
The sub will be designed so oxygen tanks can fit under a prone Goss. And the 13-foot long sub will be controlled autonomously, with no inside steering mechanism, so Goss can focus on pedaling as fast as he can.
The sub won’t be airtight – water will enter the vehicle – so Goss will have to be connected to oxygen at all times. It will also be designed so Goss can make an easy exit if needed. And five other members of the team will have to be certified as scuba divers so they can be under water with him.
Testing the device might seem scary, but Goss isn’t worried.
“Safety is a huge part of the project,” Goss said. “Also, I’ve had my share of crashes, so I figure it wouldn’t be worse than those.”
Bryant said the team hopes to break the current speed record of 5.3 mph. But to get there, the team will need to fine tune their creation, which they plan to do by testing the waters locally – in the ocean.
“I think we’ll need to get testing as soon as possible because it’s going to be a bit of trial and error,” Doig said.
After all, creating a vehicle that moves like a shark is a novelty.
“It’s a bonkers thing to try,” Doig said. “And if it works, it’ll break a world record! If not, I don’t think anyone will regret being part of BioSub. It’s really out there in terms of the engineering the students are tackling, and that’s a cool place to be.”
