The animation below shows a very small platform with only twelve floats grouped in three clusters.  To leverage economies of scale, platforms typically contain hundreds of floats grouped in scores of clusters.  The floats are weighted such that they are half submerged when at rest in still water.  This allows the floats to perform equal work on both their up-strokes and downstrokes.  The floats are connected to a drive mechanism which turns a generator.  The resistance of the generator impedes the movement of the floats.  This is why the floats in the animation become almost completely submerged before they exert enough lifting force to do their share of the work turning the generator.  The same physics apply when waves recede.  The floats don't start to fall until the they are almost completely out of the water, and their own weight then overcomes the generator's resistance.  The sizing of the generator is such that it requires the combined effort of the floats to drive it at speed.  As shown in the metrics panel at the bottom of the animation, when an individual float reverses direction, it briefly stops - performing no work.  Although each float in a cluster passes through the same transitions, their differing positions cause them to encounter the transitions at slightly different times - so that the overall cluster still performs work. 


Ocean waves are random.  Although similar, they are, nevertheless, distinctly unique.  They have different height crests, different depth troughs, different angle slopes, and different length periods.  The waves in the animation are randomly generated to exhibit all of these characteristics.  The floats ride the waves at slightly different levels of submersion depending on the angles of the wave slopes.  On steeper slopes, they are further in or out of the water (depending of the direction of travel) because they are traveling at a faster rate, and are, therefore, pushing harder (i.e., doing more work turning the generator).  The amount of work being performed by each float at any given instant is also displayed in the Individual Floats section of the Metrics panel.


The platform is anchored to the ocean floor in much the same way a ship is anchored.  However, in addition to the anchor line acting as a tether to keep the platform from drifting out of place, an electrical cable also runs down it to the ocean floor, and then to shore where it is connected to the power grid.  A platform larger than the one shown in the animation (i.e., one with many more floats) would have a very stable power output level - similar to the Cumulative Average shown in the Metrics panel.