Done it. Depends on the child and the parents.
The child has to be well-behaved and capable of going places (shopping, store, car ride) without throwing fits over inattention or boredom or "Idonwanna". Able to be placed in a life jacket because that's what we do above deck, period, no debate or argument.
Which all speaks to how the child was raised.
Given that, and given a spare hand to take care of the child? No problem. Just plan ahead, limit the time out, consider seasickness, sunburn, boredom, all the usual childcare issues when there's not going to be a 7-11 around.