A grappling iron is a metal hook, tied to a line and thrown at enemy ships so they may be pulled closer. It is also called a “grappling hook” or “grapnel”. It’s a period charge, found in the arms of Stewyne, mid-16th C. [Bedingfeld 58]. The grappling iron is drawn with three or four flukes; it is palewise, flukes to base by default, though when held in a hand, the iron’s flukes are to chief. For related charges, see anchor.
Hernando Herodes Montenegro de Mondragon bears as a badge: In pale two grappling irons of four hooks, conjoined at the ring sable.