There are different sizes and types of fenders. The measure is, of course, related to the size and goes hand in hand with the size of the boat. Instead, the type is more related to the intended use on board. Speaking about materials, there are two main categories: PVC inflatable fenders, the classic ones and the most common, and closed-cell foam flat ones.

PVC fenders can have cylindrical or spherical, “ball” shape. They have a valve for inflation and two eyelets for their fixing (which can be vertical or horizontal when used, for example, on the transom), while the spherical fenders have only one eyelet.

PVC models are cheaper and have the advantage of being able to move them easily and quickly along the ship’s sides, simply by rolling them. They have, however, the disadvantage of waving a lot and leaving the hull uncovered in case of violent forward-backward movements of the boat. To overcome this weak point, some secure them all together with a rope through the low eyelet, creating a sort of “battery” in series.

Foam fenders, on the contrary, move less and you can use them on deck during navigation as comfortable seats or mattresses; however, their lightness is a disadvantage since unwanted displacements caused by the wind are not rare. Thanks to their large area, these fenders are perfect for the transom.

On the quantity and type of the fenders, everyone does as he sees fit. However, generally speaking, you should consider that on small boats (up to 7-8 metres) six cylindrical fenders are sufficient, of course three on each side: one at the maximum beam and the other two towards bow and stern, not too advanced nor arrears. Over 7-8 meters and up to 12 metres, eight fenders are advisable. To these it is necessary to add at least one to keep on deck, at hand and with its rope, for emergency interventions during a manoeuvre.

On the other hand, spherical fenders are usually suitable for the quarter or, in other cases, for the starboard bow, but it depends a lot on individual situations and on each boat’s features. Some need to protect more the stern (because of the backwash) rather than the quarter because during the manoeuvre they have no one near; while there are those who, on the contrary, have a very tight place and need to protect the quarter, and in this case the spherical fenders are the most suitable.

Once decided number and type, it is advisable to cover them with the appropriate “socks” or fender cover.

There are different types and prices, but they are worth buying: as well as giving a touch of elegance, above all they protect the ship’s sides from possible stains caused by repeated rubbing of PVC on fiberglass.

Choosing the right size fender
Consider these factors when selecting the appropriate size for your fenders: Yacht Length Overall, Yacht Displacement (weight) and the anticipated mooring conditions.

There is an old-fashioned rule of thumb that will give you a starting point before making a final decision based on these three main factors.

Rule of Thumb 1 = 1 inch fender diameter or 2 inch round fender diameter for every 4 or 5 feet of yacht length overall.

The rule has been interpreted and converted approximately into modern metric equivalents in the table:

Frequency Guide
There is another old rule of thumb for this as well.

Rule of Thumb 2 = 1 fender per 10 feet of Low Waterline Length (LWL) with a minimum of 3 for boats of 20 feet or less. The rule has been developed into a modern metric measure equivalent.

How to set up boat fenders
Fenders need to be deployed in a proper fashion, paying due care and attention to the spacing and height of the fenders and assessing what proportion should be round rather than cylindrical fenders.

Deploy at least one fender amidships (maximum beam), with the remainder spaced appropriately fore and aft from the centre outward.

When mooring alongside another yacht (rafting up), an extra fender or two amidships will be required for adequate protection. An additional round fender deployed fore and aft will help to fill the increased gap between the topsides.

Hang fenders so they are always clear of the water or even higher when required by the pontoon height. Secure the fender lanyards to strong, deck level anchorage points. Avoid using lifelines or guard wires if possible because they are not designed to withstand the potential stresses and strains. A lower attachment point maintains the fender in position better by lessening the arc or swing.

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