Ok im on the 4th level with the snowy tanker and I have taken out everybody but I cannot figure out how to seize the ship??? Ahhh this is drving me insane!!!!

you must not have taken out everyone. did you take out the captain? he should have been the very last person and then the helo comes to pick you up.

who was the last person you took out?

i got to the top of the tanker, called the one guy and disabled their communications. Then I went into the control room and killed 3 people i think then there wasnt anyone. So I walked out around to the part where you get on the ship and took 2 people out, then the last person i took out was at the top of a tower then i cant find anyone

Face the front of the ship. To the left of the control room somewhere is a ledge you can jump over. It should start a sequence where you see the captain run towards the front of the ship.

edit:

I think the ledge that you jump over is directly above where you get on the ship. That is, if you get on the ship by dingy.

ok thanks for the help
i got on the ship by getting in the little boat and hitting the button to hoist myself up

alright, you took out the three guys at the front of the boat. now facing the front of the boat, on the right side there is a hatch that will take you down into the ship. that's where you find a couple more guys and the captain.

check you 3D map if you need more clarification.