Global Flood: The Security Guard's Last Ark

The sea rose in one night and the land stopped existing. Beck Zivan was a security guard then. He lashed together bamboo rafts by hand and got people off the rooftops onto them, and he kept doing it while the water kept coming. When a raft was carrying more than it could hold, the people already aboard decided who had to go, and they picked him. He went into the water knowing every face that pushed him. He wakes up again before the flood, with a Savior System attached to him: each person he pulls out of the water upgrades the vessel under his feet. He starts building early this time, and the raft becomes a boat and then something with an engine and cabins. He is careful about who he lets aboard, because berths are the only currency left. Others survive too, and not all of them accept his rules. Rivalries form on the water, alliances break and re-form, and there are people circling who want the ship rather than a place on it. He keeps a short list in his head of everyone he owes and everyone who owes him, and he intends to settle both. On the radar there is a new point of light coming in fast, and he does not know yet what it is carrying.