Re: Babies on Boats
Had my 2 month old out on the boat on memorial day and she loved it, slept pretty much the whole time. Like others have said, keep the baby in the shade. In our boat, that means under the bimini at all times and usually in the carrier under the bimini. We've had friends bring their babies along with them (last year we had a 1 month old with us). We don't worry about their neck strength anymore than we usually do when they are being held or driving in the car (the roads around here aren't exactly smooth). If it's warm, you do need to keep them hydrated.
I also have a boy that is 2 and 1/2, and he went with us all last summer (so he was 1 and 1/2). I made sure he always had the infant PFD on, even though he hated it. He loves to sit in the bow and feel the wind in his hair. I took him out on tube with me as well (both this year and last year), although we kept the speeds pretty slow.
As for getting mom comfortable, think of the frog in boiling water. If you want to boil a frog, don't just throw him in the boiling water. Instead, put him in cold water and slowly heat it up. Same idea with the wife. Start with the baby going out on small bodies of water, for short periods and slow speeds only. With time, your wife will get more comfortable with having the baby out during "normal" boating.