One tactic would be to shoot the vessel and cause it to sink thus spilling the terrorists into the water. Sort of like shooting the tires out of a fleeing vehicle. This would be dangerous though and could result in the death of the Captain.
How bout 2 navy seals with night vision goggles come underneath the both and end the pirates lives in the first .5 seconds of engagement. This is getting idiotic.
I was talking with my very good friend who is a former SEAL ... team one. He said use re-breathers .... swim under the boat and sink it quitely. When the terrorists/pirates hit the water ... well ... no prisoners