The 5 lb. board will float you higher than the 6 lb. board if the volumes are the same and the materials have the same density(and your mass remains the same). The 5 lb. board has less mass. But, your right, you probably wouldn’t notice. When you thin that board you are going to change the mass(weight if you prefer) and the volume. Steel battleships float because they have a huge volume that displaces more water than the mass of the battleship. Punch a hole in it and let water in the mass increases. Once the ship’s density become greater than 1.0 g/cc it sinks. All I am saying to you is it’s the density of an object and the density of the medium that determines buoyancy. Mass and volume are measurements and the density is a calculation. Mike
Indeed, but you said: the more air the more bouancy.
But a vacuum board has less air and more bouancy.
Have you ever dived? Why are filled oxygen tanks heavier and float less than empty oxygen tanks?
It’s not the air that does is it is the volume! that give the bouant force, and the more weight you put in or on it is the counteracting force. So more dense materials will sink because the bouant force is lower than the “sinking” force.
So if the board is vacuum, it is lighter. So it floats better. Like Mike said earlier, the water does not know what is inside the board.
(this is hypothetical, in practise you would need to make the board stronger and heavier. It is just to prove that it is not the air/gas that makes it float. It is the density)
Buoyancy is affected by the combined mass of the board and surfer on top of it. A 2-lb difference in board weights will amount to less than 2 % reduction in total surfer+board mass for a 175-lb surfer. Effects of 2 lbs less board weight on total mass, and therefore “buoyancy,” would be negligible.
However, beer is a diuretic. And the consumed volume of beer plus some additional fluid will be lost, in short order, when the rider must urinate. Add to this, the cold water will cause vasoconstriction and the kidneys will interpret this as an increase in total fluid volume. End result is more fluid loss to urination – and total surfer+board mass will fall below their original combined weight before drinking 3 pints of beer.
Ahh but which beer?? The bouyancy of some beer is higher than others, due to a more vigorous fermentation, resulting in a lower final gravity ( viscosity ), hence "lighter" than a beer of the same original gravity that has had a less complete fermentation, resulting in a higher final gravity ( viscosity ), and therefore less bouyancy. UK pint or US pint? or an aus schooner, which for some reason is a different amount depending in which state of australia you're in.
Air has mass(and therefor weight) fills a given volume and density can be calculated(better yet just look up the density of air). Suck out the air in a tank you decrease the mass, decrease the density(cuz we didn’t change the volume), and become more buoyant in water. The principals of buoyancy in water are basically the same for buoyancy in air. Think about a helium balloon. You all probably learned this stuff in 8th grade, but, if you were like me were too busy checking out that cute little thing sitting to your right.
Ah, beer, now were talking. I think I will have one. Mike