The tactic i use in sinking ships is this: first look at your ship identification after you pick a juciy target,chect the ships draught and set at least a few meters below the draught ie: medium merchent draught 9.0, set to 9.5 with a magnetic pistol, aim smack bang in the center and you will more than likely destroy the ship with one fish...THIS IS A TESTED AND PROVEN WAY AND IT DOES WORK...SO HAPPY HUNTING