So a few days ago I took the boat out for a little fishing. After launching I went to get my life jacket out of the storage compartment and found that it had deployed. Got me to thinking how did that happen. Well after a little research on how they work I found out that the bobbin that holds the striker back is nothing but a plastic ring with some chalk like powder packed in it. When it gets wet it dissolves and lets the spring loaded striker hit the co2 cartridge. Supposedly you should inspect it annually and replace it every 3 years. Mine was only a little over a year old but the bobbin was stamped Aug 15. From the looks of it the powder had dry rotted if that makes sense. Just glad I wasn't wearing it when it deployed. Probably would have scared the holy heck out of me.

no kidding might have caused you to fall in!

Actually they are a pressed block of material that dissolves in water. Too much humidity can cause them to slowly dissolve until the rest of the material fails and releases the pin. I have had them go off in a compartment several times. I kick myself every time for not taking them out and keeping them in a dry place.

I had one go off fishing one day. I wasn't wearing it at the time and it was on the seat. Sounded like a gun shot. My PTSD kicked in and I hit the deck and crawled under the console. My buddy thought it was hilarious and I did too after I realized what happened.

I have had one go off while fishing and I almost fell in the lake because of it. I had to hose the front deck off afterwards.

I have used these type PFD's for years and the best solution I have found if you want to store them on your boat...store them in a sealable plastic bag to keep the bobbin from degrading from the humidity...and inspect them each year...During this check it is a good idea to manually blow up the air bladder in the PFD and let it sit overnight...just to make sure it doesn't have any leaks. Last year I had one that would not stay inflated overnight...it was 10 years old. When your bobbin and cylinder are due for replacement jump in the water with it on to test it..I let my grandson do that for me...which he really enjoys...When it deploys will definitely get your attention

XLarge Ziploc bags

The HIT series by Mustang don't use a bobbin/pill, but instead are activated by water pressure. So rain, spray, humidity etc won't affect them. But, they are more expensive than the bobbin types.

You are already discussing issues with auto inflating PFD's
Are you really going to trust your life to one of these?
There are pfd's which do not restrict your movements and still keep you afloat.
Check out the
NRS Chinook PFD
This one does not make me hot in the summer either.