Somebody, please (PLEASE!) correct me if I’m wrong.

Flotation is about how much water a board displaces.

Flotation is not about how much a board weighs.

Flotation doesn’t depend on foam weight (except in the most miniscule way).

Let me elaborate.

If I weigh 150 pounds, and my board weighs 8 pounds and displaces X pounds of water, then for the sake of arguement, lets say I’ll float with the water’s surface at the level of my belly button.

If I weigh 150 pounds, and my board only weighs 4 pounds but displaces the same amount of water, then the net difference of the system is only minus four pounds. In other words, instead of a fixed displacement’s positive boyancy floating 158#, it is floating 154#. That is only a 2.6% difference, and I’m not sure any of us could tell. Could you tell the difference in boyancy if your shaper shaved an extra 26 thousandths of an inch off your next blank? That’s a 2.6% difference

Of course, all the above is assuming the surfer weighs only 150 and the difference between boards is a full 4 pounds. With a 180 lb surfer comparing a 7 lb poly to a 6lb epoxy, the change becomes even more miniscule.

Taking the surfer out of the equation, positive boyancy equals the amount of water the foam displaces minus the weight of the foam itself. A cubic foot of 1lb eps would only have 1lb less positive boyancy than a cubic foot of air. I don’t have the actual figures for boyancy, but when we’re talking about a trying to submerge a cubic foot of air, that one pound doesn’t amount to much.

So, I have to ask, why do so many surfers, and even so many shapers, continue to believe that certain foams and certain weights of foam are “more boyant” than others?

As differences in blanks, I can understand stiffer, more flexible, lighter, less inertia, heavier, more responsive, less environmentally aware, more likely to piss off your neigbor, less likely to delaminate…

But I just don’t get “more boyant”.

As I said to begin with, please correct me if I’m wrong. This is an itch I really needed to scratch, for some time now.