Just a historical footnote. In the late nineteenth century, it was not at all unusual for sailing captains to voyage with their families aboard, including very young children. I interviewed a lady who had spent her early years aboard her father's lumber schooner.

As I understand it, the trickiest parts of any voyage are those around land - reefs and shoals, and all of that. Once you are well away, your priorities change and you can relax to some degree. Coastal voyages aren't trivial and there are shipwrecks aplenty to prove it.