A fender is a cushioned device—usually made of inflatable vinyl, rubber, or foam—hung over a vessel's side to act as a shock absorber. It protects the hull from damage when docking, anchoring, or rafting against another boat. While sometimes informally called "bumpers," true fenders are portable, protective items.

Key Aspects of Boat Fenders:
Purpose: To prevent damage, such as scratches, dents, or structural harm, caused by contact with docks, pilings, or other boats.

Materials: Typically manufactured from durable materials like rotationally molded vinyl, rubber, or soft foam, often with air filled inside to absorb impact.

Types: Available in various shapes and sizes, including cylindrical (best for general docking), spherical (often used for bow protection or high-impact areas), and center-hole options.

Placement: They are suspended vertically or horizontally along the hull's rub rail or at the widest points of the boat.