As many of your know, we have done a large amount of voyaging in larger boats. We have a small ditch bag, which we even take in the dinghy. Just recently we added a Personal EPIRB, GPS enabled.
This is a river rafter's type water proof bag, clear sides with scrim about 12" high, and 6" diameter, it has a shoulder strap.
List:
Personal EPRIB, GPS enabled. ARC)
Submersiable VHF radio, AA battery and rechargable battery
Submersiable GPS/plotter, AA battery
Mini Strobe, flashlight, ARC AA battery
Hand bearing compass.
Cigarette lighter
Space blanket (two if two of use are in the dinghy--and when on the main boat)
Flares, self contained,
Smoke pot, two
Signal mirror
Whistle, small air horn
Pair Vise grips,
Gerber multipurpose tool (like it better than Leatherman)
Spark plug wrench
Set of plugs for the dinghy
At least a dozen AA batteries in a sealed container
Red distress plastic flag about 3 x 3 feet
First aid kit:
Triangular bandage
Telfa square
Tripple antibiotic ointment
Betadine swabs & clear antiseptic swabs
bandaids
Meclazine
3" Ace bandage
4 x4 gauze pads and 3" kerlex bandage
Laminated copy of drivers license, credit card (both sides) and passports.
A small fishing kit.
We also have an ARC ditch bag, (Floats, 18" x 14" x 6") It is about with a large 406 EPIRB, more flares, two more strobes, some more batteries, a second waterproof VHF, hand held flares, some high energy food, hand water maker, several pints of sealed water, vitamines, some light but warm clothing, two extra space blankets, and trap. We are going to add a satellite phone. We have antibiotics and more first aid supplies plus some of our personal medications in sealed containers in this bag
We have two decks of cards, a water proof small sharpie and a notebook (to plan our next boat).
The small bag goes with us everywhere--on land, and in the dink if we are going to be anywhere with some risk. The larger ARC bag stays of the boat, but is velcroed and can be removed in an instant.
These are assembled with my experience of putting together medical kits for cruisers and corresponding with over 300 cruisers during the last 30 years.
We have never had to ditch a boat, but I have done some foolish things--one of which left me up a salt water rapids with the tide going out in a 12.5' RIB and I had to spend the night. Called Marie on the VHF, had enough food and water to be comferatable, used the space blankets and currled up until the tide came back in. We had to use the various tools a number of times, even cut a piece of hypralon out of the inflatable's foreward deck to make a diaphragm for a fuel pump on the outboard....