Finding the Right Boat Fender Size for Your Vessel
Share
Protecting your boat’s hull shouldn’t be an afterthought. A fender that’s too small or incorrectly positioned can leave your boat vulnerable to damage when docking or rafting. Use this guide from Marine Outlet to choose the right fender size, number, and type for your vessel and docking conditions.
Why the right fender size matters
When you tie up your boat — especially in a marina or alongside a jetty — your hull comes into contact with fixed structures, pontoons, or other boats. Fenders act as a protective buffer, absorbing shock and preventing scrapes, dents, and gelcoat damage. Choosing the right size and number of fenders helps preserve your boat’s finish, performance, and long-term value.
Key factors to consider
Before purchasing your boat fenders, think about:
● Boat length (or waterline length)
● Freeboard height (distance from waterline to deck)
● Docking environment (calm marina vs open or tidal mooring)
● Hull shape and beam width
These details help determine the most suitable fender size and shape for maximum protection.
Fender size guide
There’s no one-size-fits-all rule, but a good guideline is:
● For cylindrical (or “sausage”) fenders, allow roughly 25–30 mm of fender diameter for every 1.2–1.5 m of boat length.
● For round (or “ball”) fenders, go slightly larger — around 50–60 mm per 1.2–1.5 m of boat length.
Example guide:
| Boat Length | Recommended Fender Diameter (Cylindrical) |
|---|---|
| Up to 6 m | 100–125 mm |
| Around 8 m | 150 mm |
| Around 10 m | 200–250 mm |
| Around 12 m | 250–300 mm |
If you often berth in exposed or high-traffic areas, it’s wise to size up for extra cushioning.
How many fenders do you need?
A common rule of thumb is one fender for every 3 m of boat length, with a minimum of three fenders. For example:
● 6 m boat → 3 fenders
● 9 m boat → 3–4 fenders
● 12 m boat → 4–5 fenders
Spacing them evenly along the hull — with one at the widest point — ensures consistent protection.
Placement tips for better protection
● Hang fenders so the bottom just clears the waterline — not too high or low.
● Position one at the maximum beam, and others fore and aft.
● Tie fenders securely to cleats or stanchion bases, not lifelines.
● Adjust height depending on dock type and tide level.
● Remove or stow fenders while underway to prevent wear.
Choosing the right fender type
Different shapes suit different boats and docking styles:
● Cylindrical fenders – Ideal for most small to mid-sized boats.
● Round or ball fenders – Perfect for larger vessels or rafted boats.
● Flat or modular fenders – Useful where storage space is limited or for special hull shapes.
Fenders made from durable marine-grade PVC or EVA foam offer excellent UV and impact resistance — a smart investment for long-term protection.
Care and maintenance
A little upkeep goes a long way:
● Rinse fenders with fresh water after use, especially in saltwater.
● Avoid harsh cleaners that can weaken the material.
● Check for proper inflation and inspect lines for wear.
● Store in a cool, shaded area when not in use to extend their life.
Quick checklist
✅ Measure your boat’s length and freeboard
✅ Choose the right diameter and shape
✅ Use at least one fender per 3 m of boat length
✅ Hang fenders correctly for best protection
✅ Rinse, check, and store regularly
Final word
At Marine Outlet, we stock a wide range of boat fenders, ropes, and docking accessories to keep your vessel protected and looking its best. Whether you’re moored in a marina, tied up at a jetty, or rafting alongside mates, having the right gear makes all the difference.
Need help finding the perfect fender for your boat?
👉 Call us, message us online, or shop now at MarineOutlet.com.au for trusted marine products and friendly advice from boating enthusiasts who know their stuff.