This standard defines the methodology of measuring hull roughness of vessels in dry-dock. This standard does not mention the type of instrument/gauge for such measurements. This standard is limited to a methodology—no interpretation of the results obtained is presented.

Cautionary statement: Instruments using differing measurement techniques may not provide comparable results.

This standard does not refer to biological roughness, or structural issues such as weld lines, hull plate distortion, etc.

If an out-docking survey of a particular vessel is compared with the next in-docking survey, the average hull roughness will probably have increased. This is usually because mechanical damage has occurred in service, or the coating system has degraded partially, causing increased roughness. The mean hull roughness (MHR) value measures the roughness of the hull surface covered in one pass of the instrument/gauge, whereas the average hull roughness (AHR) measurement gives an indication of the overall hull roughness including areas of mechanical damage and/or paint defects.

Some coating systems (such as “foul-release” coatings) may not render themselves well suited for some instruments/gauges used for hull roughness measuring.

Caution should be used in instrument/gauge selection and operation. The instrument/gauge manufacturer’s instructions shall be followed.