Treason at York by John F. Hayes

From the back of the book:
When Alan Crawford hid just for fun in the gloomy hold of the old York Belle, he little suspected that he would reveal a plot that was to affect the lives of many, and perhaps threaten the very existence of the Canadian colonies themselves. For this was June of 1812, and war had just been declared - the war which was to carry fire and sword even into the town of York in Upper Canada, where Alan's family had made their home. Caught up in a web of violence and treachery, Alan falls into the hands of American forces and is carried a prisoner to enemy territory.