Time Castaways — James Axler

In the nuke-altered America of the twenty-first century, time conspires against survival, especially for a legendary group of warriors led by Ryan Cawdor. Born and bred in Deathlands, Ryan dares to unlock the secrets buried deep in the wreckage of a planet. Time may be the enemy in the daily struggle to stay alive, but perhaps it can reveal something better....

Barely escaping a redoubt hidden in an old aircraft carrier guarded by killer droids, the companions emerge into the backwater world of Lake Superior's Royal Island. Here, metal and salt are commodities worth killing and dying for, and two rival barons rule mutant-infested land and water with blood will. But though Ryan was hoping for honesty and fair trade, he's soon in a death race to stop the secrets of the gateways from becoming an open passage to the future's worst enemies....