How many fenders do I need to protect my boat when docking?

For most cruising boats between 25 and 40 feet, carry four to six properly sized fenders, with at least three rigged on the docking side and one spare within reach. Hull shape, displacement and berth exposure determine the final number: a heavy boat against a rough wall needs more protection than a light boat beside a sheltered pontoon.

Choose fender numbers and sizes

Start by checking where your hull touches the berth. Fenders must sit between the hull and the pontoon, wall or neighbouring boat; six hanging above the contact point offer little protection.

Use these figures as starting points for conventional cylindrical fenders, not fixed requirements:

• Boats under 25 feet: carry four, usually around 150 to 200 mm diameter, with three available for the docking side.
• Boats 25 to 35 feet: carry five or six, usually around 200 to 250 mm diameter.
• Boats 35 to 45 feet: carry six, usually around 250 to 300 mm diameter.
• Boats 45 to 50 feet: start with six substantial fenders and add extras for exposed berths or rafting.

Choose the larger diameter in each range for heavy displacement, pronounced topside flare or regular swell. Check the manufacturer's sizing guide against your boat's weight as well as its length. For comparison, the Hallberg-Rassy 48 Mk I equipment specification lists six fenders: two 10 × 25 inch and four 12 × 30 inch.

Cover the contact points

For a normal alongside approach, place one fender near the hull's widest point, one forward and one aft of it. Concentrate them along the section likely to touch, rather than spacing them evenly from bow to stern without regard to hull shape.

1. Before entering the berth, lower the fenders and secure their lines to suitable strong points.
2. Set their height so the thick body covers the pontoon's rubbing edge throughout the boat's expected movement.
3. Keep one spare within reach, with its line attached, for a crew member to move to an unexpected contact point.
4. Once moored, check from the pontoon and reposition any fender being squeezed upwards or missing the edge.

Hang cylindrical fenders vertically for most floating pontoons. A horizontal fender can help at a low edge, but secure both ends so it cannot swing away. Tie to cleats, substantial stanchion bases or other suitable attachment points; avoid loading unsupported guardwires. Never put a hand or foot between the boat and the berth.