Dock Fender Sizing Calculator
Determine proper fender size and quantity for safe docking
Fender Recommendations
Recommended Fender Size
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Minimum Quantity
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Fender Diameter
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Fender Length
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Energy Absorption
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Spacing (approximate)
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Fender Board Recommended
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Coverage per Side
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Standard Fender Sizing Guide
| Boat Length | Diameter | Length | Quantity |
|---|---|---|---|
| Up to 20' | 4-5" | 15-18" | 3-4 |
| 20-25' | 5-6" | 18-22" | 4 |
| 25-35' | 6-8" | 22-27" | 4-5 |
| 35-45' | 8-10" | 27-32" | 5-6 |
| 45-55' | 10-12" | 32-42" | 6-8 |
| 55'+ | 12"+ | 42"+ | 8+ |
Fender Placement Guidelines
Positioning
Place fenders at widest point of hull (maximum beam) and at any hard points that could contact the dock.
For sailboats, position a fender at the chainplate/shroud area to protect the hull.
Fenders should hang so the center is at dock level, covering from waterline to rubrail.
Fender Boards
Use fender boards when docking against pilings to spread the load across multiple fenders.
Board should be hardwood or HDPE, 6-8" wide and long enough to span 2-3 fenders.
Essential for uneven surfaces, rough pilings, or when leaving boat unattended.