Race to the End of the World: The Mapmaker Chronicles Book 1A. L Tait
'A map of the world? Why did the King need one of those? Besides, everyone knew that if you went too far in either direction you'd fall off the edge, and if that didn't kill you Genesi the dragon of death would be waiting.'
The King is determined to discover what lies beyond the known world, and has promised a handsome prize to the ship's captain who can bring him a map of the whole globe. To do that, they'll need mapmakers - and 14-year-old Quinn is shocked to be one of the chosen. While his older brothers long for adventure, Quinn is content with a quiet life on the farm, but when word of his special talent gets out, he has no choice but to pack his bags and join the mismatched crew of slaves and stowaways on board the Libertas.
The other competitors will do anything to win, but the greatest danger may come from the strange sea monster hot on their tail or the mysterious uncharted lands for which they are bound. Nobody knows what lies off the edge of the map, but Quinn is about to find out that it's more than anyone bargained for . . .