Which knot is most suitable for joining two ropes of unequal size?

The sheet bend is the most suitable knot for joining two ropes of unequal size due to its design and functionality. This knot has a simple structure that allows it to securely connect ropes of different diameters while maintaining their strength and stability. The way the knot is formed enables it to grip the different thicknesses effectively, minimizing slippage and ensuring a secure hold between the two ropes.

In contrast, the bowline creates a fixed loop at the end of the rope and is not intended for joining two ropes together; it is primarily used for creating a loop for various applications, such as securing lines or hoisting equipment. The water knot is specifically designed for joining two ends of webbing together and is not well-suited for ropes, particularly of differing sizes. The figure-eight bend, while it can connect two ropes, generally performs best when the ropes are of similar size, as it relies on even distribution of tension to prevent slippage. This makes the sheet bend the superior choice in scenarios involving ropes of unequal diameters.