Because the exposure to the marine and offshore environments, slips and falls are a significant source of personal injuries on floating vessels and offshore equipment, probably the rate of personal injuries due to slip and falls in a marine environment is substantially greater than most industry groups.
Although there are a good number of publications, books and articles written regarding the subject of slips and falls, there are almost none addressing the conditions found in a marine and offshore environment, which influence slips and falls.
In floating vessels, the motions and the trim and list, influence the basic cause of slips and falls, and on offshore platforms or jack-up rigs, slips and falls are related to the oily environment that some times extends further than the drill floor. In both cases, the normally high humidity contributes to slips and falls and in some locations dust from coal or from chemical creates slippery environments.
The following glossary is included to avoid misinterpretations of the terminology used:
Friction - The force, which resists the relative movement of two surfaces in contact with one another, such as between your shoes and the surface you walk on.
Static Friction - The resisting force at the instant relative motion begins.
Dynamic Friction - The resisting force when movement is occurring without interruption. Dynamic friction is usually less than static friction.
Anti-Slip Coefficient of Friction - The ratio of the force required to move one surface over another to the total force vertically applied to the two surfaces.
The anti-slip coefficient of friction, is commonly identified as "u":
The static anti-slip coefficient of friction occurs at the point of action where the heel of the shoe makes contact with the walkway surface.
In this case, if the anti-slip coefficient of friction is too low, the person generally falls backwards onto the buttocks.
The dynamic anti-slip coefficient of friction involves the sole of the shoe coming in contact with the walking surface.
Momentum: The quantity of motion is a body as measured by the product of its mass and velocity.
The generally accepted industry standard is that a static anti-slip coefficient of friction of .50 or above is safe on a dry walkway surface. A value below .50 indicates an unsafe walkway surface. There are some exceptions: The American with Disabilities Act Accessibility Guidelines indicates a minimum Coefficient of Friction of .6 for level surfaces and .8 for ramps.
But this guideline should not be used alone when evaluating slip resistance. The influence of the footwear must be included.
Also, the above consensus applies to same-level falls in floors that are, for all practical purposes, horizontal.
But the floors or decks on a vessel are rarely horizontal. There is almost always some trim and list/sheer and camber and there are motions.
Furthermore, there are localized structural deformations created during and after construction, which may affect the anti-slip coefficient of friction, and finally the presence of water, oily substances or powder, mostly on exterior walking/working areas is more common than in land-based facilities.
Hector Pazos, is a Naval Architect, Marine Engineer and a Registered Mechanical Engineer and has been engaged in Accident Investigation/Reconstruction for more than 40 years. He has been retained as an Expert Witness in over 1,200 Maritime cases, related to both commercial vessels and pleasure crafts, for both defense and plaintiff.
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