Basic medical incidents, from sunburns to seasickness, are bound to happen when you spend enough time on your boat. The U.S. Coast Guard advises that you keep a fully provisioned first aid kit on board, and that you make sure everything in your kit is up-to-date at the beginning of each season.

They recommend that you stock your kit with over-the-counter medications like:

Pain relievers and fever reducers
Stomach remedies for motion sickness
Creams to treat insect bites and sunburns
Antiseptic and antibiotic ointments

They also suggest that you carry a mix of bandages, including:

Adhesives in various sizes
Sterile gauze pads
Roller bandages
Narrow adhesive strips

It's also essential to have emergency phone numbers such as poison control, your doctor and your emergency contacts on board.