An Unthinkable Ship

In the film Titanic, there is a scene where the ship’s designer, Thomas Andrews, confronts the grim reality of the claims that his ship is unsinkable. “She’s made of iron, sir! I assure you, she can [sink]... and she will. It is a mathematical certainty,” he says. It begs the question of why we build things that float from materials that don’t?

At Ohio Northern University, the answer to that question is simple: Because we can. In fact, ONU has an entire team of students who work all year devising new ways of doing just that. And this spring, the ONU Concrete Canoe team got to show off its skill at doing the unthinkable against other colleges and universities at the 2016 American Society of Civil Engineers (ASCE) North Central Student Conference.

You read that correctly. A canoe. Made of concrete. It might sound like an absurd premise, but it’s actually not impossible. In fact, engineers have figured out how to make a rather decent boat out of pretty much the last thing you would ever want to cling to to stay afloat.

The secret is that concrete is a very versatile material. It’s created with a formula, or recipe, of ingredients. Depending on those ingredients, it can be made strong or made weak. It can flex, or it can be brittle. It can be heavy, or it can be relatively lightweight. Use the proper recipe and apply some basic boatbuilding principles, and concrete can float.

Anyone who has ever bought a bag of concrete from a home improvement store knows what it looks like. There is a fine powdery component (cement) and a bunch of small rocks (aggregate.) When mixed with water, the cement undergoes a chemical reaction that causes it to harden around the aggregate, which makes the resulting material strong. Since commonly available concrete is used mostly for construction applications, strength is more important than weight, but it doesn’t have to be heavy. By replacing the rocks with a lightweight aggregate like foam pellets or polyester fibers, and by reducing water weight, concrete can be light enough and yet still strong enough to build a canoe that will float.

ASCE concrete canoe competitions are really excellent teaching tools because they push engineers to apply the sum of their engineering prowess toward gaining a competitive edge. The focus isn’t on just building a canoe out of concrete, it’s about trying to build the best canoe out of concrete. Every single aspect of the building process is analyzed and refined, from the hull design, to the concrete formula, to the canoe construction itself.

Building a canoe like this does not happen quickly, and it cannot be done alone. The ONU team was 27 students strong, with each one contributing considerable time to the project from the very start of the school year. As project manager, Emily Puleo, BSCE '16, had to first build a team that could tackle each aspect of the endeavor before she could ever build a boat. Leadership roles existed on the team for experienced students in the form of team officers. There was a hull design officer, a mix design officer, a construction officer and an aesthetics officer. The team also had a paddling coach and a fundraising and recruitment chairperson.


“Voting is usually pretty unanimous,” says Puleo. “We don’t think to nominate someone new when someone has experience doing that job. I always try to get someone underneath every officer so they know what they are doing and can take over the next year.”

With the officers in place, the team began to build their canoe. The first step was hull design. A 170-pound canoe requires a lot of energy to paddle, and the last thing the team needs is to fight to keep it going in a straight line. That’s why hull design officer Victoria Smith, BSCE '16, incorporated a keel, or shallow “v” shape, to the bottom of the boat to help them paddle true. The hull was designed on a computer, and the file was sent to a company that built a mold from Styrofoam, which the team has traditionally built its canoe around. However, the team built the canoe inside the mold this year, as for the first time ever, the team had a female mold made. Puleo hoped that it will save the team from sanding the canoe, which is a necessary yet time-consuming step to help reduce drag on the canoe as it moved through the water.

With the hull designed and sent to the mold-maker, a group of team members searched for the perfect balance of the best ingredients for the concrete mix. In all, ONU’s team tested a dozen different mixes before settling on one to use in the construction of their canoe. The third step was the mixing and bagging process. This allowed the team to make small batches of the concrete on “pour day” so that they could work with them in an efficient manner and ensure consistent curing. Pour day is a bit of a misnomer, as there’s no actual pouring of wet concrete like you might for a sidewalk. Instead, part of the team mixed small batches of concrete and shaped them into flat sheets of uniform thickness that another group of students then applied to the mold’s inner surface like tiles, blending the edges together as they went. After the entire canoe is covered, a layer of plastic mesh reinforcement was placed on top of the concrete. The team completed this process a total of three times over a very long day.

Then it was a month before anyone touched the canoe again, as the concrete needed all of that time to cure properly. This was the perfect time for the team to work on its paddling, and so that’s what they did every Sunday night right in the ONU natatorium in a big red fiberglass canoe.

“The pool’s not that big, so we are really good at turning. It’s going straight that is more difficult,” says Puleo.

On Saturday, April 7, the ONU Concrete Canoe traveled to the campus of Michigan State University, the site of the very first ASCE national intercollegiate concrete canoe competition in 1988, to compete with their canoe in and out of the water. The North Central Student Conference was more than just a rock regatta, especially this year when weather led to the cancelation of the actual races. Still, each team presented a technical paper that explains how they made the canoe and answered questions about the choices they made throughout the process. The ONU team finished second overall and christened their boat "Lionheart" on Neiheiser Lake at a victory celebration on campus.