I think I read this short story more than 20 years ago. The premise is: a group of men (who are white) hire a boat (or raft?) with a guide (who is black) to take them on a trip across a sea. The men are obviously racist and do not treat the guide like a person. The entire trip they completely ignore the guide; they never offer him water and they rarely talk to him. The guide doesn't speak to the men unless spoken to, and he spends most of his time crouched in the corner of the boat. Somehow they get stuck at sea and they have a limited supply of water. The white men begin fighting over how to ration the little water they have left and end up killing each other due to this. At the end of the story it is revealed that the guide has an abundant supply of sugar water stored in tanks under the boat, and all that time he was crouched in the corner he was sipping the water through a straw.