Hmmm ... are they inferring that Sea Captains aren't persistent? I'm willing to bet some of those rat-eating, sailing-off-the-end-of-the-Earth early explorers would have begged to differ. And what about pirates? I don't recall reading that Black Beard lacked stick-with-it-ness. "Give me your earrings or I'll cut your throat" ... well, I suppose that's actually "insistent." Food for thought. :-)
Great QuillSpiration.
Quill