There was recently a long good thread about offshore med kits either here on on the
www.cruisersforum.com site. The main difference between industrial first aid and offshore first aid, is that offshore you need to plan on being 2-10 days away from any type of outside aid. "Wilderness first aid" is about the only similar topic. You may need to stabilize wounds, administer antibiotics, seasickness meds, etc. for several days even if you can call for help, because it may take that long to get a ship to you and helos have a surprisingly short range, especially in bad wx.
Commercial kits can give you a good start (and a well organized case) at a price, but everyone still wants to do extensive mods on them, to fit personal needs and situations. For the basic "every day stuff" the $10-20 kits from WalMart or Costco are a REAL bargain. Using these for the little things lets you keep the "injuries" box closed and dry for more serious problems.
There are also some new products with names like "Quik Clot" that are sold as a powder, or a pre-impregnated bandage, designed to stop bleeding on wounds. They're absolutely incredible, invaluable additions that are just being sold in pharmacies in the last two years now.