PSA: Gangplank should not have a metal arm.
Pirates shouldn't have heavy ass metal limbs for the same reason they don't wear metal armor.
They spend most of their time on a boat. And if their boat goes down, they can't afford to be wearing metal while in the water.
If Gangplank's ship were destroyed for a second time he would die for sure because he would surely sink to his death.
And yes, I know gangplank is supposed to be ruthless but he's certainly not an idiot. If anything he should have a wooden arm.
is magical and allows
to swim or something like that.