Help out whenever and wherever you can.  But be sure to ask first.  Show some interest in what the skipper is doing and have him or her instruct you on proper procedures.
During docking, be still.  It seems like every time a boat gets close to the dock, you see people gathering up their belongings, moving about and getting ready to debark.  This can be distracting to the skipper, so just sit tight until the boat is moored.
Have the skipper of the boat let you know about safety procedures, if you don’t know them already, and point out where safety equipment is located.  If anything should happen to the pilot, it’s a good idea for at least one guest to know how to summon for help.
Don’t carry luggage or heavy items on with you.  Boats can list severely when the weight balance is upset.  Either put your heavy item on the boat first and then you get on or vice versa.
Offer to help clean up once your trip is done.  It usually takes one person an hour or two to organize the equipment, clean up trash, washing off the boat, and other mundane activities that responsible boaters must do to take care of their boats.

Be thankful that you have a friend who cares enough about you to bring you along on their boating excursions.  They can be amazingly fun get-togethers that you will remember for a lifetime.  But make sure those memories are good ones.  Be a courteous guest, and do your part.

Boating is an excellent way for families to get together and spend time with each other.  That means that kids will be along as well.