How to Use Boat Bumpers and Fenders

A cruiser offers a guide to the enlightened art of using boat bumpers and fenders.

| |When pulling up to a dock with pilings, place a fenderboard between the vertical piling and two fenders tied to your sailboat’s lower lifeline (top). This spreads the load and protects the hull if the boat rocks back and forth in waves. Avoid using a single fender tied horizontally (bottom), as it can become dislodged.|

The rules for sailing in Japan are simple: Do as you’re told. So when the Aburatsu harbormaster indicated that my wife, Diana, and I should raft up next to a run-down fishing scow, I turned in Roger Henry, our 36-foot Damien IV steel cutter, without hesitation. As we approached it, I saw jagged shards of wood and rusty bolts jutting out from the splintered rubrail, poised to wreak unspeakable havoc upon our boat’s topsides. I yelled forward to Diana to drop our 32-inch-diameter polystyrene fender over the starboard side. We named this disposable orange monstrosity Freddy Fender because its job was to “be there before the next teardrop falls.” We barged in boldly and tied up, lying a safe distance off.

Throughout our three months in Japan, we anchored only once. Every other night we either rafted up to rough fishing boats or tied to industrial wharfs. And yet, thanks to an arsenal of fenders, stout fenderboards, and some well-honed tactics, we escaped without so much as a flesh wound.


The following boat bumper and fender types and tips should help you keep your boat’s topsides in tip-top condition.

Always deploy the fenders from the boat, not the dock. This allows the fenders to follow the hull in tidal conditions and to be adjusted from the deck, and you can make a quick escape, if necessary, without leaving them behind.

Use the right knot. When attaching fenders over a lifeline or rail, I use the slippery clove hitch because it’s easy to tie, quick to release, and holds well. If I’m routing the line through a padeye or similar piece of hardware, I change to a slippery half hitch with a long tail. (To tie the slippery version of these two popular knots, fold the bitter end over on itself to form a bow that can be easily untied.)


To secure boat bumpers and fenders, I use 5/16- to 3/8th-inch-diameter lines, which are strong, chafe resistant, and easy to tie and untie. Don’t use polypropylene, as its innate slipperiness makes it unreliable. Note: The market is full of catchy little gizmos—hangers, portable cleats, stow straps—that we’ve found are mostly unnecessary.

When you’re rafting up or lying alongside, safety lies in size more than numbers. A battery of undersized fenders isn’t as effective as two to three fenders of the right size, style, and placement.

I carry two large-diameter cylindrical fenders. These are more easily stored than round fenders and have several specific applications. Many cylindrical models include longitudinal ribbing to prevent rolling. I prefer the center-hole style to the tabbed-end versions because there’s no weak point to tear through. Both work well against flat surfaces.


| |When rafting up, a single row of fenders (top, left) isn’t as effective as deploying fenders from each sailboat and placing a fenderboard between the respective sets (above). The increased distance between the boats helps prevent contact between the hulls or spreaders; a large-diameter fender deployed by the dockside boat cushions the weight of the second boat. To make a fenderboard, choose a 6-foot length of a 2-by-8 or 2-by-6 plank (top, right). Drill 3/8-inch holes the width of the board at either end, then feed 5/16-inch line through the holes and secure with a figure-eight stopper knot.|

Using cylindrical fenders behind a properly constructed and deployed fenderboard is the only safe way to fend off from exposed piles on jetties. A fender laid horizontally doesn’t have much tolerance for fore-and-aft movement and inevitably slides out from between the pile and topsides. (See Figure 1)

When rafting up to another vessel, deploy from the host vessel a fenderboard backed by two cylindrical fenders. Directly across from these, hang two cylindrical fenders from the visiting vessel. This technique doubles the space between the hulls, protecting not only the topsides but also the spreader ends. (See Figure 2)


Most marine chandleries sell hard-rubber fender attachments that slip over the ends of a standard 2-by-4 board. This, while useful for a quick deployment, doesn’t stand the vessel as far off a piling as a 10-inch backing fender does. Also, a fenderboard made from a 2-by-6- or from a 2-by-8, if of sufficient length, sits more securely on the fenders and is wide enough to double as a boarding plank.

I carry one large and two small teardrop fenders. The large teardrop is essential when you’re using a spring line to maneuver out of tight docking spaces. (See Figure 4.) The power of the boat is diverted by the directional pull of the spring line, thus creating a stationary turn. The hull can easily pivot around a large teardrop fender without damage. (For more on spring lines, see Earl MacKenzie’s “Dock with Ease,” in CW’s July 2012 issue.)

All the fenders described above are pneumatic, or air filled; they’re designed to offer a lot of cushion. Another type, the solid closed-cell foam fender, is very strong but doesn’t compress much. Such a fender tends to make a lot of noise against the hull and in extreme conditions can conceivably dent the hull.

| |A large teardrop or round distress-orange fender has multiple uses: a trip line for a sea anchor (A), the center fender when rafting up or lying side to (B), an anchor marker (C), or a float on your ditch kit (D). Mark the buoy with your sailboat’s name and documentation number for easy identification. A carabiner spliced onto the end of a short tether allows the fender to be easily deployed for any of these uses.|

A softer version of the solid fender is the flat fender. I use cable ties to connect two of these to make a flat fender that’s long enough to hang from the aft rails right to the waterline. This prevents the dinghy from slipping under Roger Henry’s hard chine near the transom and doing serious damage. An added benefit is that when our overly adventurous feline falls off the boat, this fender can be easily scaled from the waterline all the way to deck level. We always throw it in the dinghy for beach parties because it makes a handy fireside seat.

When you tie fore and aft to a jetty or harbor wall, commonly known as Med mooring, any pitching motion can cause serious damage to the stem or stern. Some fenders on the market are specifically shaped to accommodate plumb stems or sugar-scoop transoms. As it’s nearly impossible to keep these fenders in place, they should never be relied upon. Adjust the spring lines to absolutely ensure that the vulnerable ends can’t come into contact with the dock at any stage of the tide. Use the lengthy fenderboard mentioned above to access shore.

If stowage space is an issue, large inflatable fenders may be the answer. They have an inner bladder protected by an outside envelope, usually made of Hypalon. Their size and light weight are assets, but beware of punctures from sharp protrusions and exerting excessive pressure against the rather fragile inner bladder. They can be inflated using a standard dinghy pump.

| |To maneuver in wind or current, tie a spring line forward of a large, round fender and back down to push the bow out. Or place the fender at the bow and turn against it to force the stern out.|

In über-ugly situations, such as when transiting the Panama Canal or being pinned against a cliff wall by 70-knot williwaws in the Chilean channels, I’ve successfully employed old car tires as fenders. Tires are universally available, indestructible, and cheap.

But for normal use, a little more initial investment made to secure a higher quality of fender will pay off in performance and longevity. That said, even the most durable of fenders aren’t impervious to degradation from ultraviolet light. For the fenders we keep on deck, we use covers that help keep the fenders clean and protected from UV exposure.

By nature, dock dirt is ground deeply into fenders. Use a strong soap rather than solvents to clean off oil or tar stains, as the solvents virtually melt the soft rubber that’s used to make the fenders.

Lastly, at the risk of sounding like a pedantic old salt, remember that these devices aren’t called bumpers. Their job is to fend, and the whole point is to avoid things that go bump in the night.

Alvah Simon and his wife, Diana, are CW contributing editors.

To watch a video of how to tie on a fender, click here.