Congratulations on your new crewmember... we just had our first, four months ago, but haven't taken her sailing yet. Not for not wanting to, but it's a long commute to the boat and we keep having other things to do on weekends.
I am gonna echo the sentiment that babies are simple. However, I have seen parents carting around loads of gear for their kids that to a large extent is unnecessary. I don't know how big your boat is, but carrying stuff to and storing stuff on my boat is a big limiting factor for us. Anyway, here's our plan for when we do start taking her sailing, which will hopefully start in January or February with daysails on weekends:
1) If you're breastfeeding, you don't need to bring special food for the baby, and her immune system will be stronger.
2) If you're doing EC
, you don't need diapers either.
3) Entertaining babies is easy, too: learn a few sea shanties; my daughter falls asleep to The Flying Dutchman
4) Forget strollers and prams; get a good front carrier. It packs up small and keeps your baby feeling warm and safe. If you use public transit to get to your boat (our trip is about two hours with three transfers) a stroller can be a hassle. There's really no place in our boat for a car seat, so there's no incentive to bringing it along. Mommy can keep the baby in the carrier and work the tiller while daddy handles everything else.
5) Don't go out of your way to be quiet around your baby, for example when she's asleep. You don't want her to depend on quiet when there's always noise on the boat.
Take this advice with a grain of salt, of course, because we haven't actually taken ours to the boat yet. We'll probably start with a weekend spent at the dock just to see how she "fits" on board; you never know, she could hate it, but I doubt it.
Good luck, and keep us apprised!