If you drink seawater, will you pee more or less?

a sailor stranded on an island drinks seawater to quench his thirst. what will happen? some say he will urine more to get rid of excess salt and dehydrate to death, others say he will not urine as he is already dehydrated, and he will die because blood cells shrink because they are dehydrated and cannot carry out metabolic functions. so how will he urine and die?