![]() Lines lying on the seabed often move axially more readily than they move laterally. The friction force applied never exceeds R, where is the friction coefficient and R the seabed reaction force. The values given below are recommendations from Taylor and Valent. Seabed friction coefficients OrcaFlex applies Coulomb friction between the line and the seabed. Transverse values will be greater, perhaps by 50% to 100%. The context of both of these references is the contribution of chains and cables to anchor holding power, so we assume the friction values given are axial. Instead, in most cases, the sliding friction coefficient should be used this will usually be conservative. OrcaFlex does not, however, support this distinction. Some information is given in Puech (1984) and Taylor and Valent(1984), both of which distinguish between starting friction and sliding friction: starting friction is greater, to represent the "breakout" force. The friction coefficient for contact with elastic solids is specified on the friction coefficients data form. These friction coefficients apply to seabed contact only. The axial friction coefficient may be set to '~', meaning that the lateral friction coefficient is used for all directions of motion. For intermediate directions, OrcaFlex interpolates between these two values. This is represented by having different friction coefficients for motion in the lateral and axial directions. The friction force applied never exceeds $\mu R$, where $\mu$ is the friction coefficient and $R$ the seabed reaction force. OrcaFlex applies Coulomb friction between the line and the seabed. ![]()
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