Monday, July 27, 2009

Water Resistance - My least scientific method

In the past few days, I decided to test my Adanac Navigator II for water resistance. This of course is the least scientific method available to mankind. However, before we get to that, lets have a look at what water resistance is all about.

Basically water resistance is the measure of the degree to which the watch can resist the ingression of water. There are several features in a watch that can help make the watch water-resistant. The most important in the gasket/ o-ring that are fitted to a watch. These gaskets are made of rubber, nylon or Teflon and are fitted where the watch is at its weakest in terms of water intrusion. This means that they are fitted at the joints where the crystal, case back, push-piece (in chronographs) and crown meets the watch case.

Of course the thickness and the type of the material used in the manufacturing of the case and crystal have an impact on the watch ability to resist water. Thicker crystals and case tends to indicate a better ability to resist water ingression.

Design plays a part as well. A screw-down case back and crown contributes to a watch's water resistance. A screw-down crown acts like a lid on a jar, which helps to prevent water from going into the watch via the watch stem.

It is important to remember (me included) that the level of water resistance is a theoretical at best. The rating refers to the ability of the watch to keep water out if both the watch and the water are perfectly motionless. There conditions are of course never met in real life. Movement of the arm while swimming is enough to generate an increase in the pressure for which the watch may not be rated for.

There are of course different rating and measurements of water resistance. I hope the table below helps with understanding what the watch is capable of (or not). Water resistance is measured in atmospheres (ATM), feet or meters (m). Listed below are some common water resistance levels:

1 ATM/ 33 feet/ 10 M: protected against accidental exposure to water, e.g. splashes, sweat
3 ATM/ 100 feet/ 30 M: protected against brief immersion in water, not for prolonged swimming
5 ATM/ 165 feet/ 30 M: protected against hand washing, swimming in shallow water, not for SCUBA diving
10 ATM/ 330 feet/ 100 M: protected against hand washing, swimming, pool-side diving, not for SCUBA diving
15 ATM/ 500 feet/ 150 M: protected against the above and snorkeling
20 ATM/ 660 feet/ 200 M: protected against the above, skin diving and SCUBA to depth not requiring helium gas
30 ATM/ 1,000 feet/ 300 M: saturation diving possible

For more information and a good read on the 2 ISO standards to which these watches have to meet:

Now back to my experiment. I wear most of my watches and don't baby them. I somehow find it disturbing that my Adanac Navigator II is only rated to 3 ATM, yes 30 M. I mean this is a watch built to military standards (claimed). It must be able to do well. OK, so the argument for the low water resistant rating is because it is a pilot's watch and do not need to be rated that highly. Well, what happens when the pilot have to 'dunk?'

So my proposed 'scientific' experiment. Please do this at your own risk and your watch as well. Put on the watch and have a hot shower, watch is soaped and washed and dried, all in the bath room, which is still warm as the mirror has fogged up. Now out of the shower, into the bedroom with the air-condition running and the temperature set at 18 degrees Centigrade. Well I did say this is the least scientific method. Did it survive? Did it fog-up? Nope, it did not.

My conclusion? I guess most manufactures would rate a watch to a specific rating but test the watch to a higher rating, at least to ensure it meets the stated rating. My caveat of course is that you need to check the seals and gaskets at least once a year and the older the watch, the worst the water resistance of the watch. So don't expect that 65 year old W.W.W. to have the same water resistance rating it originally had today.

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