Ultimate Holding Capacity The prediction lines above represent the equation UHC= A*(W)0.92 with UHC as the Ultimate Holding Capacity in tonnes and A a parameter depending on soil, anchor and anchor line with values between 24 and 110. The Stevpris Mk5 design line very soft clay represents soils such as very soft clays (mud), and loose and weak silts. The line is applicable in soil that can be described by an undrained shear strength of 4 kPa at the surface increasing by 1.5 kPa per meter depth or in the equation Su = 4+1.5*z. with Su in kPa and z being the depth in meters below seabed. In very soft soils the optimum fluke/shank angle is typically 50 deg. The design line sand represents competent soils, such as medium dense sands and stiff to hard clays and is based on a silica sand of medium density. In sand and hard clay the optimal fluke/shank angle is 32°. The medium clay design line represents soils such as silt and firm to stiff clays. The fluke/shank angle should be set at 32° for optimal performance.