No, no children that I saw wore shorts, they adhered to the dress code. We just sailed on Summit to Bermuda on June 18th with a 4 year old and a 10 year old. My daughter, the younger, was always in a sundress, bows in hair and "fancy" dresses on the two dressier nights (she called them fancy but they weren't anything over-the top). The 10 year old boy wore short sleeved button downs (think J Crew) and chinos in pink, blue, cream, etc. with boat shoes, driving mocs, etc.
I think the issue for a lot of people who are replying to your post is that it seems just by posing the question, you're trying to see what you can get away with. If others aren't sticking to the dress code, then maybe you don't have to either. If they don't follow the rules, then I don't need to either. Again, seems that way from the back and forth I've read above and maybe that's why you aren't getting as much/type of feedback you're looking for.