DIY Amphibious Cardboard Boat Build & Redesign

Initial Cardboard Boat Build

• 💡 The project begins with the goal of building a miniature boat that can be sat in and powered by a gas motor, inspired by expensive commercial options.
• 🛠️ The primary material chosen is cardboard, with layers of stringers and a car-board pattern for the floor to add strength.
• 💧 Total Boat epoxy is applied to waterproof the cardboard structure, with the understanding that any water ingress would signify failure.
• 🪵 A quarter-inch plywood deck is used as a less-than-ideal but more durable alternative to cardboard for the top surface, also to be fiberglassed.

Amphibious Features and First Test

• ⚙️ A metal frame is integrated to handle engine power and provide mounting points, along with wooden runners to ensure straight tracking.
• 🚗 Wheels are added to make the boat amphibious, with a custom-designed mounting system for the wheel.
• 🚤 A 15 horsepower Mercury outboard motor is attached for initial testing on the lake.
• 📉 The first test reveals the boat is sinking, indicating the cardboard is becoming waterlogged, though it initially functions as a boat.

Redesign with Foam Core

• ♻️ Recognizing cardboard's limitations, the project pivots to a foam core for improved durability and water resistance.
• 🏗️ The steel frame is reused, and the foam is shaped with knives, making the build process easier and more confident.
• 🌊 Fiberglass and Total Boat epoxy are applied to the foam core, with a subfloor built inside for standing.
• 🚤 A new, lighter six horsepower two-stroke engine is acquired for the redesigned boat.

Amphibious Functionality and Improvements

• 🔧 Aluminum boat brackets are custom-made using PCB Way's CNC services for improved strength and foldability.
• ⚡ A hub motor is integrated for amphibious movement, though initial aggressive braking causes issues with the fork mounting.
• 🌊 The redesigned boat is tested, showing improved performance and the ability to transition from land to water smoothly.
• ⚠️ Challenges remain, including the motor's struggle on the boat ramp and the need for better traction, suggesting future improvements like fatter tires or a double-wheel setup.
• ✅ The final foam and fiberglass boat is registered and functions as a capable support vessel, with lessons learned from the initial cardboard build's failures.