How to Measure Boat Fenders and Buoys for Covers
A clean, well-fitting cover can help limit rubbing between a fender and the boat. Measure the fender in the inflated condition recommended by its manufacturer, without squeezing it with the tape.
What to measure
- For a cylindrical fender, measure the widest circular body circumference, body length and overall length, noting the rope eyes.
- For a round buoy fender, measure the widest horizontal circumference and total height, including the eyelet where relevant.
- Record the actual taper, shape and attachment positions; two fenders with a similar diameter can need different covers.
Use circumference only for circular sections
For a circular cross-section, diameter = circumference ÷ π. A 50.3 cm circumference is about 16.0 cm diameter; 91.1 cm is about 29.0 cm. These are calculation examples, not confirmation of a particular manufacturer’s model or cover size.
Match your measurements to the cover
Use the selected cover’s own size chart. Fabric stretch, closure position and the amount of body coverage vary by design. Check clearance at the rope eyes and keep the covers clean: trapped grit can still mark the hull. A sleeve does not replace a correctly sized and inflated fender.
