Not just that, the angle of your body matters too. It can be seen as how far is the projection of your CG on the water. If you were able to stay horizontal, just above water, it would be the most effective position.
The force vector is gravity, vertical. The lever is the distance between the vector line and the center of rotation. That distance is measured by projecting the perpedicular line from the center of rotation towards the vector line. That is the horizontal distance between the lower hull and the projection of your CG on the water.