Just in case you didn't know Jim Drake invented the Windsurfer, we need to thank this genious. Anyway I wanted to understand early planing and found an article where he is interviewed and he explains some of the technical stuff about early planing.

On early planing boards he had this to say:

The laws of physics tell you that a wide planing surface area will plane in less wind and at a lower speed than a narrow planing surface.

When you make a board wider you have to compensate by making the board shorter.

The shorter you get the more significant the length of the oncoming wave becomes compared to the length of the wetted surface. Implying that the windier it gets and the more agitated the water gets the less effective the wide short board becomes, meaning wide short is good for calmer, flatter days, but still has effectiveness until the forces of nature dictate otherwise.

Boards will get to 1.2 to 1.3 metres wide, and it is possible to have a board that has a width longer than it's length, and this will be trialled at some time in the future.

The dagger board will be re-introduced for ultra-light windsurfing on short wide formula style boards, and a more recreational board.

Fin's will probably have end plates attached to them in future as the length of the fin can get only so long before it becomes a logistical liability, but that the longer fin will always be most efficient.

That there is always a psychological barrier in the market for radical designs, but that once the market experiences superior performance, it will quickly accept the new designs.

These are not his exact words, but my interpretation as I didn't want to write his stuff word for word. Some of the technical stuff was beyond me
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Hardie SoftBoy