Actually, the short killing spear makes some sense, if you're seated in the canoe. Maneuverability and speed are probably more useful than length. After all, do you really want to fiddle around with a two meter pole when there's a croc near the side of the boat?
Presumably the spear is for killing smallish crocs, anyway. If it's bigger than the canoe, then attacking it in the first place would be a *BAD* idea.
Fearn