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How to select fenders

The below chart shows the relationship between the maximum towing force of the work boat and the minimum length of contact of the fender and the ship doing a pushing job. This chart gives the best size for an installed fender.

Notes:
1: As you can see from the above chart, since the influence of the length of contact is extremely large, the estimation of the length of contact should be carried out very carefully.
2: The above chart is only a general yardstick for the applicable SSR rubber fender sizes for general use. The actual size necessary will vary according to specific installation measurements.

How to use the chart

Conditions:
  The maximum towing force of the work boat 30 tons
  Length of contact 1.5 meters
Method of selection:
  Draw a line horizontally from 30 tons on the Y-axis to the 1.5 meter length graph. At this point draw a vertical line to the X-axis. This point on the X-axis gives the most suitably aiws dwnswe.
Most suitable size:
  In this case the point on the X-axis is between 700 ø x 350 ø and 800 ø x 400 ø. For safety, it is recommended that one choose the larger sized fender. Thus, the most suitably sized fender in this case is 800 ø x 400 ø.

Reference

The type of propellers and towing forces of work boats
Types of Propellers Towing force at 1000PS (ton)
2-axis propulsion (fixed pitch propeller) 5.0 ~ 7.0
2-axis propulsion (variable pitch propeller) 6.0 ~ 8.5
Kort nozzle type (fixed pitch propeller) 6.5 ~ 9.0
Kort nozzle type (variable pitch propeller) 7.5 ~ 10.5
Kort ladder type 10.0 ~ 14.0

Selection of linear type and curved type fenders

When linear type fenders are bent for installation to a ship, the outside of the fender expands and the inside is compressed. Rubber shows very strong cut resistance even against tool edges and good weather resistance under normal or compressed conditions. However, when it is stretched, the cut resistance and the weather resistance are significantly lowered. The rubber becomes subject to tool edges and oxygen ozone and ultraviolet rays. Therefore, it is safer to avoid installing a linear type fender to a boat where it will be forcibly bent.

The stretching ratio of the outside of a linear fender installed by bending is dependent upon the outside diameter of the fender and the radius (R) of the position of the ship where the fender is installed. On the basis of experience and test results, if the radius (R) is larger than four times the outside diameter of the fender, it has been observed that there is no reason to exclude the installation of a linear type fender.

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For More About Model SSR-WB:
  • Data Charts and Images
  • About Model SSR-WB
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