Here's a brief excerpt from Mike Loade's book "The Longbow"
"Crescent-shaped arrowheads may have been a type that had use in naval engagements. Often also called "forkers" these heads are most usually associated with hunting birds.
However, tests by Mark Stretton have shown that a crescent arrowhead also has the capacity to tear sailcloth (Soar 2010: 148). Mark found that by shooting with these heads using a shallow angle at heavy canvas, he created 12in tears. Multiple shots with such arrows from a pursuing ship could have the effect of slowing down the target ship, and a high wind could cause a shredded sail to rip apart even more. The extent to which this tactic was used remains speculative."
Personally, I'm not sure I buy that - if even one crescent shaped head has been found on an actual battlefield site that makes this theory somewhat void, as there aren't any sails on battlefields. It is of course possible that they were developed for sails, and then used at other situations but timelines would need to be analysed to make anything of that.
I'm seeing Mark next weekend, so I'll bend his ear about what he thinks.