Every year, we cast our canoe on ‘casting day’ with 20-30 members working at the same time. This day usually takes place on the first weekend in January after school starts. However, the entire development of the canoe is a time-consuming process that stretches over many months.
In this phase, we do research to optimize our designs for concrete mix and hull structure. See those respective sections for more details.
After the hull design has been finalized, a male mould is constructed from styrofoam using CNC machinery. This mould, made in pieces, is then assembled, sanded, and shrink wrapped to prepare for casting.
After our mix has been decided on, all its dry components are separated into 5L batches and put in plastic bags so they are ready for casting day.
On casting day, concrete is mixed and hand-cast onto the surface of the canoe. Care is taken to ensure layers are thin and uniform in thickness. After each layer of concrete (except the outermost layer), we add a layer of carbon fibre weaving, and care is taken to make sure the weaving is incorporated into the concrete. This all-day event is the most important day of the year for the team.
A humidity tent is built for the canoe on casting day, and the canoe is left to cure for 28 days. During this time, the canoe hardens and strengthens.
After the canoe has cured, the mould is removed from the interior of the canoe.
The cured canoe often has a rough, uneven surface that can be sanded down. We use a combination of belt-sanders, sandpaper, and grinders to achieve a smooth finish. This is a time-consuming process. During the sanding process, sealer is also applied to the canoe.
After the final layer of sealer, letters (either painted or decals) are placed on the canoe showing the name of the school and the canoe.
Concrete Canoe
