We have 6 (ages 11 to 14 mos.) Here's what we do:
Little ones (2 and under) are teathered in the cockpit with harnesses when we leave the dock. They are free to roam below once they're walking well (2 1/2 or so)
Keep plenty of toys in the forepeak- the forward cabin is now their playhouse
No one appears on deck with out a PFD. We favor the Mustangs as well- collar, handle and crotch strap can't be beat.
If the weather is breezy, they wear harnesses and are clipped on- by four they follow directions well enough to know to stay in a safe spot if we're running "rail down".
Lifeline netting is a good idea (especially if your normal sailing angle is 25 degrees plus-like us
Teach them from the beginning to ALWAYS STAY WITH THE BOAT
. A family was lost on Michigan a few years back and it's suspected that the kids jumped in in an attempt to "rescue" someone.
Get them involved in swimming classes NOW. Our 3 yo is already getting pretty good. The YMCA has a good program.
keep an eye on the kids. Repeat this one.
Sounds like a lot but as they get used to being on the boat they get better at keeping out of trouble and it's a great experience for them and you.
Their favorite movie is now "Morning Light"