In the US, taking the the USCG approved Medical - Person in Charge (Med-PIC) course is pretty good. Since I was a big ship Captain
(container ships, research
vessel's, cable layers) or the Chief Mate, I had to have the Med-PIC rating on my USCG License
It taught advanced first aid, how to suture and how to start an IV. In addition to the above class, I also trained with a US Navy
Maritime Hostage Rescue
Team for combat first aid. My father was an industrial medicine emergency
Doctor and later a Pathologist, so I had a another 30 years of experience from him. I had far more medical training than the normal merchant marine officer and I NEVER thought that I had enough.
Onboard ship (and to a lessor degree my sailboat) I organized and equipped the ship's hospital. My theory was to carry almost everything so that it was onboard and a land based Doctor could talk me through the treatment that was necessary. If we couldn't reach a Doctor by Sat-Phone or SSB
(and there times when we couldn't), I felt comfortable enough with my training (and the reference books
that I carried onboard and the "cheat sheets" that I had made for the treatment of the more common critical injuries), to go it alone.
At the end of the day, and what I always use to tell the crew and scientists, is you don't see "M.D." after my name or printed on my forehead - so don't get hurt!
People being people, they always ignored me - so I did treat a fairly broad range of serious injuries and medical conditions over the years. My promise to them was that I would keep them alive until the helicopter arrived (and I did have to call for helicopters) - and I always was able to do that.
When equipping your boat and getting your training, remember, you can't save everyone - so train and gear
up for what is most likely to happend to you.
I carry drugs for common infections, IV's for shock/blood loss, ephinephrine for insect/sea creature caused shock, O2 gear
, pain management drugs, medicines for eye injuries, ears, burns, sutures (major to minor cuts), breaks & sprains, and teeth.
My most common cases were resipatory tract infections, urinary tract infections (especially women), diarrihea, teeth, jellyfish stings (anaphylactic shock), eye injuries, major cuts, sprains and breaks (ankles, wrists, knee), severe sea sickness
, heat exhaustion, burns and spider bites.
These are all things you have a good chance of seeing onboard your boat, so at a minimum, be able to deal with these events
Smooth and safe sailing!