What type of knot is used for joining ropes of slightly different diameters?

The sheet bend is specifically designed for joining two ropes of different diameters, making it the ideal choice for this scenario. Its structure allows it to accommodate varying sizes effectively. The knot features a bight in one rope and uses the other rope to form a secure connection, which allows for a firm hold despite differences in thickness. This characteristic ensures that the knot remains tight under load, reducing the likelihood of slippage.

Other knots such as the overhand knot are more suitable for securing the end of a rope rather than joining two ropes, and may not hold securely if the ropes are of different thicknesses. The sailor's knot, or square knot, is intended for tying two ropes of similar diameter and can come undone if subjected to uneven tension. The bowline is a strong knot used to form a fixed loop at the end of a rope, not for banding two ropes together. Therefore, the sheet bend is the most effective option for joining ropes of differing diameters.