I agree that it is dynamic, but I think the big mistake that so many make in analyzing this particular problem is not looking at the board and rider as a unit. all of the examples of the 5 and 7 lb boards behaving differently you cited are correct, assuming that there isn’t a 150lb surfer sitting on top of them!
Take those two boards and strap a 150lb lead weight to them. Are they going to bob in the lineup noticeably differently? Well, maybe 1.5% worth, because that is the difference in buoyancy as a part of the total system.
When you go from sitting to paddling, the rate at which your board will float to the surface might be marginally quicker from the 2 lbs of extra buoyancy, but not much considering how buoyant any board is on its own. Every notice how much water a riderless board displaces by itself? not much at all. So, when you push it down with your weight, you are displacing much more than necessary to make it float, and taking that weight off it is going to make it pop to the surface like a cork. I’d guess that the shape of the board causing drag on the way to the surface would be a bigger factor in that process than an extra pound or two of core weight.
I disagree with the lighter board riding higher underway, again it is a difference of 2 lbs in a 155 lb system, and at that point it isn’t a displacement issue because the board is planing. Much more a matter of surface area and rocker/rails at that point.
On the heavier board holding in better, again, the weight applied to the wave at the rails is the weight of the board plus the weight of the rider. I just don’t believe that anyone is sensitive enough to notice a 1% difference in total system weight.
The only thing I can point to is the very noticeable difference in swing weight, inertia at the feet, that will come from a lighter board. In that context, 2 lbs is a HUGE amount, and will certainly affect the perceptions of the surfer riding the board. I might even venture to guess that many if not all of the “buoyancy” differences that surfers are reporting are actually mass/inertia differences that are simply being misinterpreted by good surfers who are feeling a major difference in their boards, but are not equipped with the theoretical background to accurately assess what is happening. I know when I’ve ridden an ultralight board after a heavy one, I feel some major changes in the way that my input is transferred to the wave. There is simply less INERTIA, less resistance to changes in velocity, and that is extremely noticeable in virtually all conditions. 2 lbs in motion at the end of 2.5 ft levers (your legs) translates into quite a bit of torque, torque required to change the velocity of the board, and torque created by the movement of the board. Even 1 lb is noticeable in that context, and likely to be remarked upon by even average surfers.
But just because they think it is a difference in “float” doesn’t make it so.
That’s my postulation on the big lighter-weight/corkiness debate. Makes a hell of a lot more sense to me, from a strictly physics-theory point of view.
Just caught the texas thing… Ha! yeah, I’m an alaskan, maybe that’s what I need to put on my sig.
). You need to make sure your shape fits your foam.
