Baby carriers developed together with Medical Experts
Our Daughter-in-law did foredeck with our granddaughter in a carrier from them.. snug, secure, with you at all times. Early on (weeks old) she had something simpler.. a cloth carrier whose name I can't recall.. will add when it comes to me. EDIT: Baby Buddha http://www.babybuddha.ca/
We did use the car seat idea a few times, but heeling was a bit problematic. Otherwise for our son, who fortuitously always seemed happy to sleep when we needed to run the boat, we made a small secure berth with a lee cloth and lots of blankets/padding to keep him put.