I am finding angle between ship's heading and component in wave (wave's angle of attack), not sure if ES is a right place to ask this type of question.

Should it be the difference between mean wave direction and vessel's azimuth.

Thank you for your time and concern reading my question,


  • $\begingroup$ I believe the answer depends on how the data is going to be used. You mention a component, ocean swell is tracked by direction, period, and amplitude of the swell, these are often divided into different components, i.e. a 1 meter 5sec swell at 275 degrees and a .7 meter swell at 15 sec and 200 degrees. If you are looking for a general effect than your answer is likely ok, but if you want to know the characteristics of a component of the swell you need to explain the question a bit more clearly. $\endgroup$
    – user824
    Jun 4, 2019 at 21:50
  • $\begingroup$ Sorry, I should make it more clear. Are there any different between vessel's heading and the azimuth. Let's say I am moving from 1 coordinate (lon 1, lat 1) to the other coordinate (lon 2, lat 2), vessel heading is calculated from Four-quadrant inverse tangent between sin(delta lon) * cos(lat2) and cos(lat1) * sin(lat2) - sin(lat1)*cos(lat2)*cos(delta lon) . While for azimuth, I am taking into account of 'World Geodetic System 1984' $\endgroup$ Jun 5, 2019 at 18:19
  • $\begingroup$ Heading is the direction the vessel is pointing it is equivalent to the Azimuth. The true course may be different than the heading due to winds and current. I am still not clear on why the wave angle is important. $\endgroup$
    – user824
    Jun 5, 2019 at 23:48
  • $\begingroup$ Hi Friddy, I am calculating vessel's speed loss during the effect of adverse weather. Wave is one of the main component and to do so, a relative angle between vessel and wave has to be treated as input. Do you know any source provide formula calculating vessel's heading beside Mercator Sailing Formula $\endgroup$ Jun 6, 2019 at 13:59