How to choose your fenders

Date posted: 8 October 2013

In boating, a fender is a bumper used to absorb the kinetic energy of a boat or vessel berthing against a jetty, quay wall or other vessel. Fenders are used to prevent impact, abrasive action from vessels, or direct pressure. Fenders are typically manufacturered out of rubber, foam elastomer or UV treated polycarbonate(243) . Rubber fenders are either extruded or made in a mould. The type of fender that is most suitable for an application depends on many variables, including dimensions and displacement of the vessel, maximum allowable stand-off, berthing structure, tidal variations and other berth-specific conditions. The size of the fender unit is based on the berthing energy of the vessel which is related to the square of the berthing velocity.
Does size matter…yes! its important to have the correct size for your boat.

Fender Size Guide:

  • Length should be 2/3 of the freeboard
  • More displacement, harsher environment = Larger Fender
  • Use at least 3 fenders when docking
  • Consider where you will store your fenders.
Part No. Diameter x Length Boat Length
White Blue cm inches metres
0061 0062 8 x 27 3 x 10 <4
0063* 0064 10 x 41 4 x 16 <4
0071 0072 11 x 40 4 x 16 4-5
0081 0082 13 x 45 5 x 18 4-6
0073* 0074 13 x 56 5 x 22 4-6
0091 0092 15 x 55 6 x 22 6-8
0451 0452 18 x 65 7 x 36 6-8
0459 0460 23 x 75 9 x 30 8-10
0101 0102 20 x 80 8 x 32 8-10
0453 0454 27 x 85 11 x 33 10-14
0111 0112 31 x 91 13 x 36 12-15
Boat Size
A Series Buoys                                       A
F Series Boat Fenders                                       F
G Series Boat Fenders                                       G
0 – 10′
11 – 16′
AB0 A1
F01 F1
G2 G3
17 – 23′
A1 A2 A3
F1 F02 F2
G3 G4 G5
24 – 30′
A3 A4
F2 F3 F4
31 – 45′
A4 A5
F5 F6
46 – 60′
A5 A6
F7 F8
61′ +
F11 F13

As the two charts show, measurements for different companies vary. Your best bet is to measure your freeboard, calculate 2/3rds and then ring the companies to ascertain which of their fenders is closest to your calculations for boat length and use. Construction. Its worth paying attention to detail here, has the fender got what you are looking for – special thimble inserts to prevent “eye” damage, all in one moulding/ separate sections, UV resistant, stainless steel needle valve adjustment for inflation/deflation, constructed from rubber/elastomer or plastic and is there consistency of wall thickness. Do you need your fender to be in a vertical and horizontal position? These are all factors to consider when replacing your fenders.
The fenders below are created from one mould with inserted thimble

The fenders below are moulded in sections with a solid injection moulded eye, as opposed to inflated eye with needle inserts.
Now for choosing the correct style of fender for the position required, for example a bow fender is useful when you moor bow-on into marina berths, you can buy these with two or three point attachment. Heavy duty spherical and bow fenders are popular with commercial users as fenders or floats, they are great to use alongside stone walls.
Here are a selection of various fenders, of particular interest is the stern fender. This can be used to protect the vulnerable stern, or they can be secured on the pontoon in various positions as a permanent form of protection on entering and leaving your berth.
Force 4 Fender Ladders - 5 Step Fender Ladder - BlueThe step fenders make climbing aboard easier from either a tender or pontoon.

Inflating the fenders

Do not overinflate as this will deform and weaken the product and voids any warranty. Indicated diameters are for inflation of 0.15 bar pressure at 20 degrees Celsius. (in hotter climates 0.07 bar could be enough) Without a pressure guage a simple test with any product is to be able to depress the wall 6 to 8mm with a light hand touch.
To Inflate • Use Anchors Double Action Pump (0311) or any hand, foot or air compressor pump, but do not set guage beyond 0.15bar pressure . Prise out the black bung (and keep for reuse) of valve with a coin or screw driver .  Insert the stainless steel needle inflation adaptor into the valve, apply the nozzle and start air flow .  Fill the product until the walls/shape are fully expanded.  Any ‘folds’ in the wall should be eased out by hand.

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If you have any comments or suggestions with regard to fenders, please feel free to add them. Meanwhile I hope you found this information useful.

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