The Enemy Is Within! — Patrick G. Cox

Having been accidentally transported forward in time from the gundeck of HMS Spartan in 1805, Harry, Ferghal and their young companion, Danny, must now make their way in a new age - one with technologies once beyond their wildest dreams and deal with enemies who seek to use them for research. When their new ship, the Star Frigate Leander, is damaged, they find themselves on a hostile world where the humans are the hunted by both their enemies and the alien inhabitants. Rescued and sent as part of a 'prize crew' to bring home a captured freighter, it is their old fashioned methods that save the day . . .