I think the 5 ATM rating would mean the second row of the table "Swim" ... it says "snorkeling" but I would think that it means snorkeling on the surface, and not going down much deeper than that. So, 15metres might be pushing it too far.
I think the ATM rating is based on static pressure, not dynamic. In other words, if the watch is completely stationary in the water it would be ok, but once there is movement the pressure on the watch goes up greatly.
But as soon as you move your arm, pressure is increasing.
yes the dynamic pressure goes up with movement, but not a whole lot. If he is moving his arm at 5 m/s (walking pace) he adds 12.8 KPa of pressure. 5 atm is equivalent to 506.6 KPa of pressure. It should be noted that the pressure does go up as the square of velocity, so if he doubles his arm speed (10m/s) he is now adding 51.4 KPa. For something like snorkeling I wouldn't really be concerned, for water skiing or something high velocity I would be pretty worried.
yes the dynamic pressure goes up with movement, but not a whole lot. If he is moving his arm at 5 m/s (walking pace) he adds 12.8 KPa of pressure. 5 atm is equivalent to 506.6 KPa of pressure. It should be noted that the pressure does go up as the square of velocity, so if he doubles his arm speed (10m/s) he is now adding 51.4 KPa. For something like snorkeling I wouldn't really be concerned, for water skiing or something high velocity I would be pretty worried.
Nice explanation.
If FR935 would be build same quality and specifications like F5 with FR935 weight and nice wearing feeling it would be perfect watch. I wear my watch 24/7/365 and I really don't like to take it off when doing certain activity. :D
yes the dynamic pressure goes up with movement, but not a whole lot. If he is moving his arm at 5 m/s (walking pace) he adds 12.8 KPa of pressure. 5 atm is equivalent to 506.6 KPa of pressure. It should be noted that the pressure does go up as the square of velocity, so if he doubles his arm speed (10m/s) he is now adding 51.4 KPa. For something like snorkeling I wouldn't really be concerned, for water skiing or something high velocity I would be pretty worried.
Your explanation is somewhat oversimplified. It does not take into account the complexities of hydrodynamics around complex shapes. The pressure at the watch face or bezel might not increase significantly with movement, but once water starts to enter for example the button crevices (which are usually the weakest points of watch-like devices), or microscopic gaps at the seals, locally the water pressure might increase drastically, because relatively large amounts of water try to enter into a very small place thus increasing pressure.
