The meaning if the two words is rather similar and not only do they share a protracted "o," that sound is easy to shout when you're heaving or hauling.

It's easy to "imagine" people saying all sorts of things in all kinds of special situations, but that doesn't mean they did, or that if they did that other people followed suit.

Presumably Colcord called her book "Roll and Go" because the phrase appears in a well-known shanty, sounds seafaring, and she liked to say it. Maybe the phrase in "Sally Brown" intrigued her as a child.

Surely if it had a technical meaning for her, she *would* have explained it.