A gunwale, pronounced guhn-l and rhymes with tunnel, is the term used to describe the top edge of the sides of a boat. The term derives from wooden sailing ships of war. Generally, gunwales were designed to provide protection to a boat from the stresses of artillery fire. In modern times, boat gunwales are used to strengthen smaller craft, hold various pieces of equipment, and serve as an anchor for oars.

The word gunwale comes from a combination of the words gun and wale. Gun refers to the cannons used on the sailing warships. One definition of wale is a narrow raised surface or a ridge. Therefore, a gunwale is a narrow raised ridge for guns.

Canoe gunwales typically are a widened band around the edge of the top of the craft. They provide structural reinforcement and offer a place to grasp the canoe when lifting or moving it, as well as serving as a barrier to hinder water from splashing into the boat. Generally, canoe gunwales are made with aluminum, fiberglass, or wood. They are also sometimes called guards or rails.

Hobbyists who build handmade wooden canoes typically recognize the importance of a properly built gunwale. A gunwale needs to be correctly built and installed or the canoe may not last long. Because of the durability, strength, and beauty of these woods, favorite woods to use for canoe gunwales include white ash, cherry, and mahogany.

Fishing boats sometimes have equipment attached to their gunwales — outriggers and downriggers can be bolted to the gunwales. Both items use a system of wires, pulleys, and clips to control the depth and position of bait on a fishing line while trolling. Trolling refers to slowly pulling live or artificial bait on a fishing line behind a boat.

A small rowboat will usually have its oarlocks mounted on its gunwale. In competitive rowing — the type of boat racing with multiple oarsmen in a long, thin boat called a shell — the gunwale sometimes is referred to as the saxboard. The hardware, or riggers, for the oars is bolted onto the saxboard. Each rigger holds a gate, which is where the oar sits.