Building a Custom Aluminum Catamaran: Engineering a Keel Cooling System

Designing the Keel Cooling System

• 💡 The team is undertaking a new project: designing and fabricating a custom keel cooling system for their dual 25-kilowatt Combi electric motors.
• 🎯 The goal is to exchange heat from the motor's coolant loop directly with the surrounding saltwater via the boat's aluminum hull.
• 🧠 AI was consulted to estimate the required surface area for heat dissipation, with initial calculations suggesting approximately 0.125 square meters.
• 📐 The design prioritizes a long and narrow heat exchanger for efficiency, aiming to fit within existing hull frames and utilize hull contact for heat transfer.

Fabrication and Material Selection

• 🛠️ The team explored using tubing versus a flat extrusion for the heat exchanger, considering surface area contact and the hull's concave shape.
• 📏 A six-meter long aluminum extrusion was cut to 900mm to fit between frames, offering good contact with both the hull and internal stiffeners.
• 🧩 End caps were designed using angle pieces, serving a dual purpose as both closure and a doubler plate to simplify fabrication.
• ✅ The fabricated heat exchangers were pressure tested with soapy water and passed, indicating they are watertight.

Weekend Adventure and Family Visit

• 🗺️ A weekend side trip to explore Moreton Island involved climbing sand dunes and enjoying the coastal scenery, serving as a reminder of the lifestyle the boat build enables.
• 👨‍👩‍👧‍👦 The arrival of a special visitor, "Mama," is eagerly anticipated, highlighting the importance of family time amidst the demanding build schedule.
• 🦀 On Moreton Island, the team observed and filmed soldier crabs, adding a touch of nature to their exploration.

Shop Progress and Patreon Support

• 🧼 The team worked on preparing and priming the boat's bilges, a task requiring absolute silence and cleanliness to ensure proper paint adhesion.
• ⚙️ Multiple projects are ongoing, including significant sanding efforts estimated at 450 hours remaining on the hull.
• 🙏 A Patreon member, Steve, visited to assist with sanding, underscoring the valuable support from the online community.
• ✨ The completed keel coolers were pressure tested and deemed ready for installation in the engine rooms.

Finalizing Keel Cooler Installation

• 📍 The keel coolers are positioned in the engine rooms for optimal heat transfer and convenient plumbing.
• 🔗 The design allows for plumbing the coolers in series or parallel, offering flexibility based on the pump and system configuration.
• 🚢 The video concludes with a look at the progress and a preview of the next steps, including fabricating shaft brakes.