As mentioned before, everything you have while living aboard will eventually fall into the water. Many friends that come to visit us have dropped their phones, car keys, and wallets into the harbor; lost forever.
Luckily (knock on wood) I have never dropped anything important into the water by following a few simple rules.
1. Never pull anything out of your pocket while on the pier.
2. If you plan on pulling something out if your pocket while on the pier or deck of the boat, put it in a pocket by itself.
3. Never pull anything out of your pocket when you are drunk. (Batman Dave dropped his cell phone, wallet, boat keys, and car keys into the harbor on Halloween while dressed as batman)
4. If you have zippers on you pockets, keep them zipped shut.
Most items are lost when you pull something out of your pocket and it slips from your hand or pushes something else out with it. For example: you take your phone out of your pocket and your keys are hooked on the corner. When the phone comes out, the keys fall. You reach for your falling keys and open your hands to catch them before they fall into the water, but you just let go of your phone! You watch as both your phone and keys fall into the water and sink to the bottom.
If you must pull something from your pocket, do it over land or inside your cockpit/cabin. It only takes a few moments to do this and it will save you a lot of frustration. If you are expecting a call, or your phone in a pocket alone. If you are not expecting a call, let it ring and call them once it is safe to retrieve your phone from your pocket.
Lastly, it would behoove you to get insurance on your cell phone. I have my phone through Verizon and the sales representative told me: If your phone falls into the harbor, simply report it as "the harbor stole my phone" and the insurance will cover its replacement.
Try to avoid the frustrating moment when you drop something in the water, it only takes a few simple steps to keep it from happening but it takes a long time to replace whatever falls.