How Much Water Resistance in a Dive Watch is Enough?
It would appear that a watch claiming to be water-resistant to 100 meters or 330 feet should be sufficient for recreational scuba diving. Especially since those safe diving limits are set at 130 feet. So what’s the deal? First off, the water-resistance ratings provided by manufacturers are from testing done under controlled circumstances. Basically they indicate resistance to water penetration assuming there is no movement by either the watch or the water, at a particular depth. Also, they don’t account for what happens if the watch is bumped or jarred. Several factors are at work simultaneously on a watch while underwater. Pressure is the most significant. At sea-level there is one atmosphere (atm) of pressure on everyone and everything. That equates to 14.7 pounds per square inch (psi). For every 33 feet of depth, divers and their equipment are subject to one additional atm of pressure. Thus at 132 feet down, the pressure is 5 atm or 73.5 psi. Furthermore, as a diver moves through th
