What type of hitch provides mechanical advantage when tightened and is considered a compound knot?

The trucker's hitch is designed specifically to provide mechanical advantage when tightened, making it an effective compound knot. This knot utilizes a combination of a loop and friction to create tension on a rope, allowing for the secure hauling or anchoring of loads. The mechanical advantage comes from the use of a pulley-like effect, which helps to effectively tighten the rope with less effort.

In contrast, while the bowline forms a secure loop, it does not provide a mechanical advantage, as it is primarily used for creating a fixed loop at the end of a line without tensioning capabilities. The half hitch is a simple knot that is commonly used to secure a rope but does not offer any mechanical advantage. The round turn serves as a method for wrapping a rope around an object but similarly lacks the mechanism for creating tension and leverage in the same way that a trucker's hitch does. Thus, the trucker's hitch stands out for its functionality in providing both security and the ability to pull with greater force, making it unique among the options presented.