I am new to this website, but I was in the Coast Guard Auxiliary for 26 years and "assisted' 256 boats that I actually did the paperwork for. Here's what I (still) carry:
legal requirement of aerial and handheld flares, and extra aerial ones left over from years past. They last a lot longer tha the 40 months written on them. however, make sure you have enough that are within the code dates to be legal.
Make up a piece of 1" PVC with a cross pin so you can put the handhelds into it and have them held overboard. The slag is hot and can start a fire in your boat. When firing an aerial one, hold it above your head. The d**n gun is plastic, and if it fails getting your hair (or hat) singed is better than your eyes getting burned. Orange flag, and smoke flares, in addition
Emergency pump. The "bicycle pump" style manual is good for bailing your dinghy. You get 6-8 strokes to a gallon. You will run out of energy before you run out of water. Buy a 750-1000 GPH rule or similar. Put about 15' of flexible hose on it, and about 20' of power wiring. Terminate with small battery clamps. Toss the pump into the bilge water, hand the hose overboard, clip the wires to a battery, and its pumping. The wooden plugs discussed above is a good idea. I got a kit with 4 different sizes using soft wood back years ago from Defender. I was relatively cheap.
Fire extinguishers. For the 25 you need a B-I, larger 2 B-I or a b_2. B-I is 2.5# dry chem, and B-II is 5. My extinguisher is a A2, BC40 with 15#. I read too many reports where someone was using a B-I and they said it was just beginning to put out the fire and it ran out....note: what to do with an extinguisher which is out of code date? Start a fire in your barbeque grill, and have each member use it to put out the fore, or coordinate with your local Fire dept for then to help you. For the purchase price even of new cheap ones, you cant get that kind of training any cheaper.
First aid kit: You bought a $9.98 at Wal mart and you think you are protected? Wrong!. Go to a fire station near the water which has paramedics. They will tell you what to have and believe me, the "kits" do not come with them. Like: Have you been stung by a Jellyfish? Wash in sea water, wear gloves when handing the tentacles, and rinse with ammonia, Yep, the same stuff used in cleaning the hose, even windex. I bought some professional strength stuff at Home depot. I think you get the point. My kit is in a medium size gym bag. Buy a book on "marine First aid". I found one at west marine for $10. O r take a red cross course. That are taught by paramedics.
Towing gear. Unless you have been trained in assist towing, do not attempt it. It looks easy, but it is dangerous for the untrained. Look at a Coast guard 44' boat. There is a chain link fence behind the helmsman. If the cleat on the towed boat comes loose, its coming at the back of the head of the helmsman. Cleat vs Person---- cleat wins
radio; Nothing else but an installed VHF marine radio, and antenna. handhelds do not have the range. cell phone, ixnay. Scenario. You are in a large lake and a person aboard has a medical emergency. SO you whip while all this is going on, I an fishing a quarter mile from you, and my fishing buddy is an off duty paramedic training officer, and my radio is turned on..... A simple mayday (Yes, medical emergencies are a mayday) and many people hear it. Help may be close.
EPIRB/locater?
Do you boat offshore more than say, 10 miles? The C G radio system is set for 20 miles to a 1 watt radio. And have a handheld waterproof radio as a back up. (I do)Other things: when i boat alone, I use the disconnect lanyard. make sure there is some kind of ladder/boarding system that can be initiated from the water.
Non-swimmers wear lifejackets. Same with children. many places that sell toys have children's jackets with cartoon characters on them. Less stress to get them to wear them. When the Captain says for all hands to don them, there should be no argument. Like a parachute-- don't do any good unless you are wearing it. The jackets should have a mirror, whistle and a strobe lamp (or waterproof flashlight). When being looked for in the water, your 1' diameter head is hard to see from more than a few hundred yards. You need a multi-media show at attract attention. In the keys I heard a radio request to look out for 2 missing divers. About 1mile from their dive site they flagged me down. They were 300 yards away, in a 2-3' sea. Without their waving and shouting, I would have went way past them.
Maybe I over do safety things, and yes, I understand we have a 25' boat, but I am alive to write about this after 50+ years of boating, offshore fishing (usually 20+ miles offshore) and ocean scuba diving.
If this is overdoing it, let me know.