Final answer:
The main characteristic of planing vessels is their ability to lift the hull above the waterline, reducing friction and allowing for higher speeds.
Step-by-step explanation:
The main characteristic of planing vessels is that they are designed to rise up and ride on top of the water when powered. Unlike displacement vessels, which push water aside as they move, planing vessels have the ability to lift the hull above the waterline, allowing them to operate with less friction and resistance from the water. This characteristic enables planning vessels to reach higher speeds and is particularly useful in various applications, including recreational boating, search and rescue operations, and military craft.