Gunnels are the upper edges of a boat's sides, and there are a number of synonyms that can be used to describe them. One common synonym is "gunwale," which is a more traditional spelling of the word. Another is "gunnel rail," which emphasizes the rail-like structure that runs along the gunnels. Other synonyms include "gunnel lip," which refers to the "lip" or edge of the gunnel, and "gunnel cap," which describes the covering or cap that can be placed over the gunnel to protect it or provide additional grip. Regardless of the specific term used, the gunnels of a boat are an important part of its structure and stability.