Nobody wants to think about the dark side of sailing... When things go wrong... Of course we have a sound boat, good weather forecast, great crew and a fun itinerary.
Let's cover the basic equipment that will minimize your chance of being "lost at sea".
Float plan - leave an appropriate float plan with a responsible adult. The Coast Guard no longer accepts them directly.
Distress signals - visual and audible. Have an orange flag with black ball and square as it's out all the time. Make sure your flares are current and serviceable. You can keep your expired flares aboard as long as you have valid ones. Put a whistle on every PFD. A CD/DVD makes a great signal mirror, look through hole and place the target between your extended hand's "peace sign" and light it up.
Flashlights - LED headlamp for each person with red light to preserve your night vision. A 1 million candle power plus spotlight for signaling and identifying navaids, etc. And another 300+ lumen spotlight preferably LED for backup and extended runtime.
PFDs - Wear them. Inflatables are comfortable and should be worn anytime topside. Invest in one with a built-in harness. Preferably a Type I is worn when things get exciting. While you're at it invest in a strobe that automatically activates when the inflatable deploys. Pen flares and a dye marker are great additions if you have the room.
Ship's VHF - hooked up to your GPS for DSC and MMSI entered. Maybe even a backup VHF antenna mounted compatible with your handheld VHF.
Handheld VHF - works when your ship's battery doesn't. Search aircraft at altitude can hear you at amazing distances and rescue craft can DF steer directly to you. Keep it charged and consider buying a handheld what accepts a separate, replaceable Lithium battery pack. If you have a GPS enabled handheld all the better. I wear it anytime I'm on watch.
Cellphone with GPS - backup communication near shore hopefully with waterproof case. GPS can be used to determine position as a backup or if off the boat.
EPIRB/PLB - at $250 who can't afford one? You have to register it for them to respond and make sure that the battery is within it's service date. A SPOT serves a similar purpose. I have both a SPOT and McMurdo FastFind on me if I'm topside alone and I give the SPOT away to the other crewmember if not.
Dinghy/Liferaft - Much better than in the water, especially if it's cold. Remember, step UP into it when abandoning ship ONLY when it sinks. Many vessels are later found afloat and the liferaft is never found.
This is a Cliff Note of equipment that helps you avoid being "lost at sea"... A competent Captain is the best insurance of avoiding the situation all together! Though sometimes I feel like Tim the Toolman with all this gear, but I'm comfortable with it and confident that I'll have what it takes to get recovered ASAP.