I have the St John Ambulance Cert given at the end of the 3 day First Aid at Work Course and have an e-mail from the RYA stating that this would satify the Yachtmaster requirement.
Professional medical or dental qualification
First Aid at Sea (DOT approved course)
Ships Captains Medical Certificate
First Aid at Work (St John, Red Cross or St Andrew)
RYA Small Craft First Aid
Public First Aid (SJA, SAA)
Essentials of First Aid (SJA)
First Aid (Mountain Act) (SJA)
Basic Frist Aid (RC)
Standard First Aid (RC)
Emergency Aid Voucher
Certain other qualifications held by Police, Fire and Armed Services
This is a few years old now, and you should check with the RYA. I did the RYA course, which you will need to re-do every five years (with a refresher after three years).
i am surprised in these days of certification that the rya will allow someone holding frcs, mrcp or even humble mbbs to get away without paying for one of their courses
While basic first aid should not require any asministration of drugs, when I did my RYA first aid, there was an optional module, which we were offered as part of the course if anyone was going on coded vessels. This covered us of MCA 'Class C' medical kits, which do indeed contain drugs, though not many.