pullups and chinups are good, do them in sets and add weight for more of a challenge. or do a ladder starting at 1 and keep adding more reps until failure. you can do rope pulls by tying a line to the cable machine to simulate sheeting. use about 75 lbs of resistance, with the adjustable pulley starting at your feet. and work up to doing 100 pulls on each side. start by doing 10-20 reps on one side and switch back and forth. those are 3 good exercises, good luck!