CLS Timber

Building the foundation of a competitive river racer To build a vessel capable of winning a local river race without mechanical assistance, you must prioritize buoyancy and structural rigidity. This project involves transforming industrial blue barrels and raw timber into a functional flotation platform. The goal is to create a base that supports a multi-person crew while remaining streamlined enough to navigate current and obstacles. By focusing on a modular timber frame secured to high-capacity plastic drums, you achieve a balance of weight distribution and durability that basic makeshift rafts often lack. Essential tools and hardware for the build Successful construction requires a specific set of materials that can withstand the tension of water resistance and the weight of a seven-person crew. You cannot rely on scavenged scraps if you intend to win. * **Buoyancy Units:** Six to eight 220-liter blue plastic barrels. These are preferred over metal drums due to their weight and resistance to corrosion. * **Structural Timber:** Twelve lengths of CLS timber or 2x4 beams. You will need roughly 3-meter lengths to ensure the raft is long enough to track straight in the water. * **Decking:** 9mm or 11mm Sterling board (OSB). Avoid heavy 18mm boards as they add unnecessary weight above the waterline. * **Fasteners:** A large quantity of heavy-duty wood screws and potentially pilot-hole drill bits to prevent splitting the timber. * **Cutting Tools:** A cross-cut saw or a powered skill saw for rapid framing. * **Safety Equipment:** Life jackets are non-negotiable, particularly if members of your construction or racing team cannot swim. Step-by-step instructions for raft assembly 1. **Acquire and Seal the Barrels:** Secure your 220-liter drums and ensure the lids are tightly sealed. These barrels provide the displacement necessary to keep the timber frame above water. Even a small leak in one barrel can lead to a catastrophic tilt mid-race. 2. **Measure and Cut the Main Joists:** Determine the width of your raft based on the number of barrels. For a six-barrel configuration (three per side), cut your main timber beams to roughly 3 meters. This allows for a streamlined profile that reduces water drag. 3. **Construct the Timber Chassis:** Lay out your main beams and connect them using cross-braces. You are essentially building a ladder-style frame that sits atop the barrels. Use pilot holes before driving screws to ensure the structural integrity of the joints remains intact under stress. 4. **Dry-Fit the Barrels:** Place the timber frame over the barrels to check the alignment. The frame should sit squarely on the "shoulders" of the barrels. Adjust the spacing so that you can still access the barrel lids if necessary for future modifications. 5. **Secure the Flotation Units:** Use braces or heavy-duty straps to lock the barrels into the frame. The barrels must be unable to shift laterally or rotate, as movement during the race will disrupt your center of gravity. 6. **Install the Decking:** Screw the Sterling board to the top of the timber frame. This creates a flat surface for the crew to sit or stand on. If you are planning for a specific seating arrangement, like using garden chairs, ensure they are bolted directly through the decking into the joists. 7. **Reinforce the Center Line:** If you plan on adding advanced propulsion, such as a human-powered paddle wheel, reinforce the center of the frame with double-timber joists to handle the torque of the mechanism. Advanced propulsion and hydrodynamics While most entrants in a village race rely on standard oars, a high-performance build considers the strength of the human body. Mashtag Brady and his team, the Splash Tag Navy, are exploring the implementation of a "hamster wheel" paddle system. Legs are significantly stronger than arms, and a geared system that translates leg power into a large rear-mounted paddle can provide a massive speed advantage. When designing your frame, consider the "cross-draft" between the two lines of barrels. If the barrels are too close, they create turbulent water in the center of the craft, which increases drag. By spacing the barrels further apart—creating a catamaran-style hull—you improve stability and allow for more efficient water flow. However, keep the total width within the limits of the river you are racing on; a raft that is too wide may get stuck in narrow canal sections or bridge arches. Troubleshooting common construction failures One of the most frequent issues in amateur raft building is the "banana effect," where the weight of the crew causes the center of the raft to sag, creating a curve that catches water. To prevent this, use diagonal bracing across your timber frame. This turns your squares into triangles, which are significantly harder to deform. Another common failure is timber splitting. Because the raft will be vibrating and flexing in the water, a split joist will quickly fail. Always use pilot holes and avoid over-tightening screws into the end-grain of the wood. Buoyancy calculation is also critical. A 220-liter barrel provides roughly 220kg of lift. Six barrels provide 1,320kg of total lift. You must subtract the weight of the raft itself (the timber and decking) from this total to find your "useful load." If your crew of seven weighs an average of 90kg each, that is 630kg of human weight. Ensure your raft has at least a 2:1 buoyancy ratio to keep the deck comfortably above the waterline. The competitive outcome of a solid build By the end of the initial construction phase, you should have a rigid, floating platform that sits high on the water. This is the difference between a "lady boy of boats" and a genuine contender. A well-built raft provides the confidence needed for a crew to row—or pedal—at maximum exertion without fear of the vessel breaking apart. With the Splash Tag Navy base complete, the focus shifts to aesthetics and secret weapons. Whether you decorate your craft as a Fiat Panda or a naval warship, the underlying engineering determines whether you cross the finish line or end up in the drink.