Resident Evil 5/Chapter 3-3

Chasing Irving
Josh will be driving the boat, and you and your partner will have to cover him. There will be two boats behind you, one on the left and one on the right. Shoot the Majini trying to shoot you and that should get those boats out of the way. Now turn around and shoot the Majini there. Eventually, the boat will stop because a gate is in your way. Get off the boat, go up the walkway, jump across the gap, and go down. You'll reach a lever. Pull it and the gate will be opened. Get back to the boat and you'll move on. Again, try to shoot the Majini that are trying to shoot you and eventually you'll come across another gate. There will be two paths here. Go to either one but watch out for the Majini behind the turrets. Have your partner go on one side while you go on the other and pull the levers simultaneously to open up the gate. Climb up the ladder, go into the shack and open up the drawer next to the door for an Emerald. Now go back to the boat and you'll be able to move on.

Fighting Irving
Once you reach him, Irving decides to inject himself and turn into a monster. Start by turning to the left of the ship and using the turrets there. Shoot down the middle of the tentacles and dodge them when you can. Once you're done with shooting him on that side, he'll be on the left of the ship. Do the same there and eventually he'll attach himself to the back of the ship. Shoot Irving as much as you can while avoiding the tentacles (unless they have to be dodged) and that will be the end of Irving. In case you ran out of health, there's a first aid spray on the opposite side of the ship. Once the battle is finished, the chapter will end.