WHICH MARATHON, CWC, MWC OR OTHER MILITARY WATCH IS RIGHT FOR ME?
A lot of people ask me what they need to look for in a military watch for diving, surfing, rafting etc. Many say "150ft (50m) water resistance is enough isn't it? I won't be going down more than 75ft (25m)." I wish it was that simple but its not. There are several important features that make a watch water-resistant. The most important is the gaskets, or 0 rings-which are made of rubber, nylon or Teflon, these form watertight seals at the joints where the crystal, case back and crown meet the case. if the watch is a chronograph, the chronograph pushers will also have gaskets and the more gaskets you have the greater the risk one might fail. In addition, water-resistant watch
cases are lined with a sealant, applied in the form of a
quick-hardening silicon liquid, which also helps keep the water out.
The thickness and material from which the case is made is also a big factor in determining whether a watch can safely be worn underwater. The case must be sturdy enough to withstand pressure without caving in. In general, this means a steel or titanium case. A screw-in case back, as opposed to one that pushes in, also contributes to a watch's water resistance. A screw-in crown, a feature of many divers' watches, helps prevent water getting into the case through the watch-stem hole. When it is screwed down it forms a water tight seal like the hatch on a submarine. Generally screw crowns are used when the watch is rated at water resistant to 100m/330ft or more. The various different levels of water resistance as expressed in meters, atmospheres or feet and are only theoretical. They refer to the depth at which a watch will keep out water if both the watch and the water are still. These conditions, of course, are never met in the real world. When you are swimming the movement of the wearer's arm through the water increases the pressure on the watch dramatically; so it can't be worn to the depths indicated by lab testing machines. Please note that we do not recommend swimming or diving with your watch unless it has a screw-down crown (also known as screw-lock or screw-in crown) and is water-resistant to at least 100 meters. Many military watches which are rated at 50m/150ft such as the MWC G10 with battery hatch are fine -based on feedback received - but be careful with the G10A range which are the basic G10 models because they are only rated to 30m or 99ft. Some chemicals can corrode the gaskets and make them vulnerable. Heavily chlorinated water can also cause problems, as can chlorine bleach, bath foams and hairsprays that work their way into the watch's seams and damage the gaskets. (They can also damage the watch's finish although this is rare with military spec watches such as CWC, Marathon, MWC, Breitling etc.) Although fairly rare on Military Watches leather straps can be made to be water resistant too. Generally however, leather straps are easily damaged by frequent exposure to water and also start to smell. So if you are going to wear your watch while swimming -- think of buying one with a metal bracelet, a rubber or Nylon NATO strap.
Definition of Water Resistance
Usage Recommendations
The following usage recommendations are suggested by most watch manufacturers.
Care for a Water Resistant Watch
It is not generally recommended to wear your water resistant watch in a hot shower, sauna or bath although I have always ignored this with all my watches and got away with it so far. The fact remains though that it is no recommended and is at your own risk if you do it because the extreme heat causes the metal parts to expand at a different rate than the rubber gaskets. This creates small openings that can allow small amounts of water to penetrate the watch. Sudden temperature changes are especially harsh if you lie in the sun and dive into cold water.
After swimming or diving in salt water, immediately rinse the watch in a stream of fresh water. If your watch has a rotating bezel, turn the bezel several times while rinsing it. This will prevent salt buildup and corrosion of the bezel ring.