5 Tips for Finding the Right Size & Type of Fender for Your Boat or PWC

Fenders are your boat’s first line of defense against damage at the dock. Here’s what to look for.

Every boat owner has likely felt the dread of leaving their prized craft at the dock, only to watch a set of wakes roll in moments later and threaten to mar their pristine gelcoat or, worse, crunch a pricey section of fiberglass. Hopefully you put out a fender or two, but is that enough…and are they the right size and type for the task at hand? 

A lot’s riding on the answer. Here are five tips on how to select the best size, type and number of fenders to protect your boat.

What to Consider When Buying Boat Fenders

Boat fenders may seem like an afterthought, but the right size, material, shape and even placement will go a long way toward giving your boat the protection it needs.

1. Fender Size & Types:

Size matters. Choose a fender diameter based on the size of your boat. An inch of diameter for every 4’ – 5’ of boat length is a good rule of thumb for the classic cylindrical fender. With an eyelet at each end, these can be hung both vertically and horizontally. If choosing ball-style fenders (typically used on larger or commercial vessels), up that ratio to 2” of diameter. An inch or two of added diameter will certainly add peace of mind on a rough day, but keep in mind fenders need to be stowed when not in use. 

Don’t overlook some of the newer shapes on the market, particularly if you have an unusual hull or dock shape. Molded fenders, as well as fenders with segmented foam sections encased in durable covers, may hold a better position, or even wrap around curves of your hull.

What you want: A set of fenders of adequate diameter for your hull length, as well as a shape that best fits its contours.

Boat Length In FeetCylindrical Fender DiameterRound Fender DiameterType
Under 10′3″Cylindrical Double-Eye, Hybrid
10′-15′3″ – 4″9″Cylindrical Double-Eye, Hybrid
15′-20′5″ – 5.5″12″Cylindrical Double-Eye, Center Hole, Hybrid
20′-25′6″ – 6.5″15″Cylindrical Double-Eye, Center Hole, Hybrid, Round
25′-35′8″ – 8.5″18″Cylindrical Double-Eye, Center Hole, Hybrid, Round
35′-50′10.5″ – 12″21″Hybrid, Center Hole, Round
50′-60′12″27″Hybrid, Center Hole, Round
60′-72′15″ – 24″27″Hybrid, Center Hole, Round
72’ +24” – 32”34”Hybrid, Round

2. Fender Material Options:

A fender’s material will not only impact its performance, but also cost and longevity. PVC vinyl is most common. It’s both durable and affordable, but subject to scuff marks. Larger vinyl fenders can also be cumbersome to store. EVA foam can be shaped to lay better against a hull and take up less room in storage, but can degrade over time.

Flexible, segmented fenders typically feature polyethylene foam wrapped in UV-resistant vinyl but may still fade or tear over time.

What you want: A fender material that not only proves durable, but also meets your budget and storage needs.

Nothing says ‘I love you’ like making sure the kids’ life jackets are snugged up and properly buckled.

Safety Tip Provided by the U.S. Coast Guard

3. Fender Quantity and Placement:

Use one fender for every 10’ of your boat’s waterline. Consider three fenders the bare minimum, with one placed at the boat’s maximum beam and the others positioned fore and aft.

Secure fenders to a cleat or rail, at a height that will offer the most protection based on the dock. Remember to take into account any tidal changes. Avoid hanging fenders too low or too high. Too low and they may dip into the water and be susceptible to marine growth, too high and they may be pushed up and out of position by wave and wake action.

What you want: An adequate number of fenders, placed at optimal positions to protect your hull.

4. Different Fenders for Different Situations

Pilings tend to roll or push fenders out of place. Fabricate a “fender board” from a pressure-treated plank hung outside two fenders, and allow that board to span multiple pilings. 

When rafting up, deploy fenders first and try to match up against boats of similar size. Watch fender height, placing both cylindrical or ball-style fenders where they won’t roll up over the gunwale or drop too low at the waterline.

What you want: Fenders that are not only properly placed, but stay in position throughout the time they are in use.

5. Proper Stowage

Don’t leave fenders hanging when underway. It’s bad boating etiquette, and will leave them exposed to UV rays or potential loss while underway. When not in use, stow fenders in a storage compartment, dedicated fender racks or trunk where they can be readily accessed and kept in best condition.

What you want: Dedicated storage to keep fenders not only close at hand, but protected from damage.

A boating course is a great way to gain confidence and boat-handling skills. A little practice now will make it look easy when everyone is watching.

Safety Tip Provided by the U.S. Coast Guard

Closing Remarks & FAQs:

Find the answers to frequently asked questions about boat fenders, including how to match fender size and quantity to boat length, average cost, as well as suggestions regarding stowage and maintenance

How does boat size impact fender size and quantity?

Fenders should be sized according to boat length, with a minimum of one fender for every 10’ of waterline.

How much do boat fenders typically cost?

Boat fenders can vary widely in cost, based on size, material, even color. A 5” diameter vinyl fender can run under $12; a comparable fender of injection-molded EVA foam with integrated line and locking cam cleat can run as high as $80.

How many fenders should every boat have at minimum?

A boat should have a minimum of three appropriately sized fenders, with a good rule of thumb being one fender for every 10’ of waterline.

Are certain materials better than others?

All fender materials have their pros and cons. Vinyl fenders are less expensive, but can be bulky and hard to store in larger sizes. Molded foam fenders are pricey, but may better lay against the contours of your hull. Best to choose a fender based on your particular needs and budget.

Is there an average cost per fender?

Fender cost varies by material and size.

How should fenders be stowed and maintained?

Fenders should never be left hanging when not in use, but stowed in onboard storage compartments, trunks or racks. Check regularly for damage. Keep inflatable fenders filled according to manufacturer’s specifications.

Are fenders needed for situations other than regular docking?

Fenders are a wise choice any time your boat may come up against any other object, be it a dock, piling or other craft. Fenders are essential when rafting up against other boats, to protect not only your boat but prevent it from damaging another.

More Buying Tips: