There is a book my wife and I used a lot to help with medical problems. While serving as missionaries in the jungles of Panama is "where there is no doctor" It is available on line and can be downloaded for free. We delivered babies, treated wounds, even broken arms till we could get the person to a clinic. Sometimes several days because of the transportation problems there.
HealthWrights: Workgroup for People's Health and Rights
Check it out and see how it could be a help for you on your boat.