Five minutes to shore when the weather is good and your engine starts. Really, please heed my advice and make sure each and every one of you knows how to do basic first aid, I hope you're never going to be in a position to use it but when you do you'll be happy you took the time and trouble. First purchase: a very good first aid kit.
This is all not to piss on your parade but because I lived in a pretty remote area for 2 years and have a little bit of experience that might be relevant to your situation.