Gunwale (pronounced 'gunnel') is a compound of gun and wale (a thick plank running along the side of a ship). The word dates to the fifteenth century, when it literally described the wale — the reinforced horizontal plank — at the top of a vessel's side where guns were mounted. Warships of the late medieval and early modern period carried their cannons along the upper sides of the hull, and the plank that bore these weapons needed to be especially strong. This functional description became the word's permanent name.
The pronunciation of gunwale as /ˈɡʌnəl/ — dropping the w entirely — is one of English's most dramatic examples of spoken shortening diverging from written form. Similar nautical pronunciations include forecastle ('fo'c'sle'), boatswain ('bosun'), and coxswain ('coxun'). In each case, centuries of daily spoken use by sailors compressed the word into a more efficient form while written English preserved the original spelling. The gap between
The wale element deserves attention. In shipbuilding, a wale is a horizontal plank thicker than the surrounding planking, used for structural reinforcement. Wales run along the ship's sides at various heights — the gunwale is simply the topmost one. The word wale itself comes from Old English walu (a ridge, a raised stripe), related to the welt on the sole of a shoe and the weal left by a whip. All these words describe raised linear features
The phrase 'packed to the gunwales' (or 'loaded to the gunwales') means filled to the absolute brim — as full as something can possibly be. The image is of a vessel loaded until the water line reaches the gunwale, the highest point of the hull. At this loading, any additional weight risks swamping the vessel. The phrase thus carries a connotation of dangerous excess — not just full, but dangerously
Modern recreational boats retain the term gunwale even though they carry no guns. A canoe's gunwale is the upper edge where the sides meet the trim; a kayak's gunwale serves the same function. The word has been completely severed from its military origin and now simply means 'the top edge of a boat' — a peaceful retirement for a term that once named the most dangerous part of a warship: the plank from which cannons fired.