another thing to consider when packing a ditch bag is the EPIRB. if its not hydrostatically mounted, then by all accounts it should be in your ditch bag. by that logic, and assuming you service and test it properly, if you have the ditch bag, you have the EPIRB. therefore, it is unlikely that, from the time of activation, you will be in the water for more than a few hours. personally, i plan for a day. with that in mind, it is most important to pack items for several key purposes:
1) warmth. whether youre in the water or in a raft, it is VITAL to maintain warmth, even if you boat in fairly warm waters (remember that water saps warmth away from your body at 3 times the rate of air). so, space blankets, handwarmer packets, knit hats, and similar items should be in your bag.
2) medical treatment. many of the reasons that a boat will sink may involve injuries to the crew. such injuries may include burns from fuel or electrical fires, bruises and lacerations caused by getting thrown around after a collision, or other small injuries sustained in the process of abandoning ship. therefore, items such as gauze, burn cream, ace bandages, waterproof bandaids, tape, tweezers, aspirin, ibuprofin, etc, should be included in your ditch bag. it is also important to keep all these items DRY. the container i use for this is a wide-mouth Nalgene bottle, which also serves the function of a drinking container to collect water or for other miscellaneous purposes.
3) location. like i said, the EPIRB which should DEFINATELY be a major component of your ditch equipment, will alert the Coast Guard to your predicament and get them to your general location through triangulation, and the 12.5 mhz beacon will help them get to within about a 1/4 mile of your location. however, viewed from the air, in fog, at night or in heavy seas, a 1/4 of a mile can be a significant distance. therefore, handheld arial flares (Orion Skyblazers), handheld "stick" flares, smoke signals, dye markers, strobe lights, laser pointers, signal mirrors, and lightsticks will provide visible beacons that will pinpoint your location. also, a handheld VHF will allow you to communicate with cutters, helos, or other boats which you may be able to see but which may not be able to see you. simple directions such as "we're dead ahead" or "turn to port" can bring rescuers right to your doorstep; one with GPS readouts like the Standard Horizon HX850S can allow you to give other recreational boats without homing equipment exact position numbers. of course, spare batteries for all equipment that use them should be carried and stored in vacuum sealed bags.
4) miscellaneous equipment. there is some stuff that you should just have for whatever purpose may arise. for me, these incluse some of the following. water, because on a hot day, dehydration is going to take a quick toll, especially after smoke inhalation from an onboard fire which can produce nasty fumes. i carry 4 bottles, which is one for each member of my typical offshore crew. gum, because, as famously stated by Kevin Costner in The Guardian, it "keeps the sea out", as well as maintaining alertness. a good multitool, because it provides all the functions of a toolkit, for whatever purpose may arise. duct tape- obvious reasons. cable ties- similar to duct tape, i can fix anything with zipties. ziplock bags, to keep personal effects (wallets, cell phones, etc) dry, as well as catching rainstorm water if you do have to survive for awhile. sunglasses, prevents eye fatigue and allows crewmembers to search for aircraft on a sunny day. sunscreen, because a bad sunburn will facilitate hypothermia once night falls. also, copies of registration papers and other vital documents shoud be kept in the ditch bag to help with Coast Guard inquiries and sorting out of incident reports.
additionally, from my perspective, my ditch bag is for absolute emergencies only, ones that result in the actual ABANDONING OF THE VESSEL. meaning, the flares, med kit, and documents inside my ditch bag are all redundant; there is a better, larger med kit and flare kit that are kept in other locations in the boat, for use should a medical emergency occur that does not correlate with sinking, or if the boat is disabled and i need to shoot flares to bring rescuers to the vessel. my thinking is, if i do not tough the equipment in the bag unless im leaving the boat (aside from testing and resupply as items expire), then all the equipment will be there when i need it. ideally, in the case of an abandon ship scenario, i will have my ditch bag, boat med kit, and boat flare kit in my life raft with me and my crew. but, even if the only thing i can grab is my ditch bag, i will have the equipment to summon and attract rescuers to my position.