I recycled the netting once found on the foredeck in the V-berth. I also discovered that I could fit an entire Graco folding playpen into the V-berth and just wedge it with pillows. Worked like a charm at first.
Our son started sailing at five days old. We took him out in 25 knots by lashing down his car seat at 10 months old...he snored and farted most of the time. Once he was walking, he learned "one hand for the boat" as soon as possible, and he knows that "on deck" means "PFD at all times". He lashes on with a Gibb hook underway, and his parents know to wear their PFDs at all times, too...something that is not legally necessary, but then when I see my next door neighbour riding his bike without a helmet with his daughter WITH a helmet in a rear bike seat or a trailer, I think: "Hmm. Hypocritical AND dangerous".
I started wearing bike helmets in the '80s as a bike courier, because I saw what happened when you failed to die after being slammed into a pole or a mailbox: a new hat size, lots of shouting and a career in basket weaving and wallet-sewing.