Careful, careful… don’t twist those words around too much, or maybe I said it porely. And don’t forget that when you’re sitting on your board, or laying, your body is in the water too - adding to the floatation.
My focus was on the science, as I’m amazed at how many people don’t really understand floatation. Unfare I guess, coming from a scientist, but I am what I am. It seems most people think the material makes something float, and a spongy, airy material should float more. I think this was illustrated when the previous poster mentioned compressed air. I believe the though here was, “Air makes things float better. A hollow surfboard with air inside should float really well. Wait… if I compress a bunch of air into the board, it’ll float super-duper well” And that’s obviously just wrong. Not to capitalize on the mistake, my appologies, but I think it illustrates many peoples thoughts on bouyancy.
My main point was that bouyancy comes from the displacement of a fluid, and the pressure that that fluid exerts on the object that did the displacement. So for surfboards it helps to think of volume, not foams and air…
Now I’m kinda middle of the road on the surfboard lightness/floatation issue. It wouldn’t be hard to look back in the archives at some of my posts where I was adamant that a few pounds meant nothing. This hit me the other day while I was sitting in the water, in a lull:
Lets talk shortboards, 6 lbs epoxy eps and 8 lb PU/PE (a little heavy maybe… I’m still working on my glassing technique) Now were talking a 25% reduction in weight - significant when you’re talking about doing snaps and feel and what not, rotational kinetic energy… blah blah blah. But does this affect paddling, drop ins, etc? As I said, I used to be a adamant “No”. Now I’m a “well…”
Most people will be quick to agree that adding an inch or two to a board (length, or maybe 1/2" width) will help paddling. We’re not talking monumental, but more than a little weight subtraction. Well, what about that 2 lb difference. In terms of volume that’s about 3% of a cubic foot (3% of 64 lbs/ft^3), which we said earlier (back of the envelope) for a shortboard is about 1 cubic foot. So that reduction of 2 pounds is the equivilent of adding abour 3% to the volume of your board, or, for a 6’3, adding about 2 3/8" in length (yes, I know, adding percentage lenth will increase volume on all sides, and probably give you a lot more than a 3% increase in volume, but it’s back of the envelope, for argument sake). Suddenly it seems more substantial, but I’m still far from convinced. Yet, I’d be fully willing to admit that I was wrong.