Lecture 7: Calculation of horizontal component, buoyancy
Therefore, it may be said that the horizontal component of the hydrostatic pressure-force on a submerged surface is the hydrostatic pressure on the centroid of the projected surface on y-z plane, multiplied by the area of the projection. Alert: line of action of the force doses not pass through the centroid! One will have to determine it.
This can be shown that this is true for all submerged surfaces. Let us consider an object whose projection on y-z plane is a triangular surface. Therefore, for such object, F_x may be calculated as follows:
(Fig. 7e)
Area of triangle ABC where,
is the depth of the centroid of
Area of triangle ABC where,
is the depth of the centroid of 
, where AD is the altitude of the triangle ABC. 
