Limitation by depth
of the channel varies a lot by the size of the vessel. Many channels have plenty of water
for small vessels, outside the markers. When I am sure there is enough depth
, I like being where the big ships CANNOT go, especially in my little sailboat. Compared to a big tug and tow, almost all sailboats are small, and with their keels can easily get sucked into the bigger vessels water
When I ran a 135' crew boat, we habitually ran outside the channel as a courtesy to the numerous really big ships that used the channel, at least when I was sure there was enough depth. They had enough to deal with, without my little boat adding to the confusion.
In a very narrow channel, or a very busy one like Galveston, the very able and very professional captains are easy to spot by their courtesy.