vulcanhammer
Geotechnical
In publications such as DM 26.5, the current yaw moment arm vs. current angle for a moored vessel is zero at 0 degrees, rises then begins to decline around 20 degrees, crossing the x-axis around 90 degrees and continuting to decrease until around 160 degrees, then rising to zero at 180 degrees. Other publications depict this almost as a sine wave, similar to wind yaw moment.
In MIL-HDBK-1026/4A, graphs of this kind are replaced by a least-squares fit function (Equation 24, 4.5.3) which generates a sawtooth type function that begins at a negative value at 0 degrees, passing the x-axis around 90 degrees and ending up with a positive value at 180 degrees.
Allowing for a sign convention change, the non-zero values for the current moment arm for current angles of 0 and 180 don't make sense. Is there something wrong here?
Note: both DM 25.5 and MIL-HDBK-1026/4A can be found at
In MIL-HDBK-1026/4A, graphs of this kind are replaced by a least-squares fit function (Equation 24, 4.5.3) which generates a sawtooth type function that begins at a negative value at 0 degrees, passing the x-axis around 90 degrees and ending up with a positive value at 180 degrees.
Allowing for a sign convention change, the non-zero values for the current moment arm for current angles of 0 and 180 don't make sense. Is there something wrong here?
Note: both DM 25.5 and MIL-HDBK-1026/4A can be found at