Writing historical fiction is a fascinating journey, even in an area where you have some professional expertise.
I began my current WIP in 2008 and finished its first draft in the same year and the fourteen months between have left me disconnected from the research I did at the time and I've had to revisit it all in the rewriting process.
Things went well for the first seventy thousand words (I'd kept all my notes in the story file) and then we reached the beginning of the final confrontation in the Caicos Passage and there was a page missing from the voyage notes and the photocopied tide tables for January 20th, 1803 in the area of the Turk and Caicos Islands were not in the file either.
Without this information it was impossible to check the accuracy of my first draft and I had to go back to replotting the movements of the four ships involved on an old chart of the same latitude and I came up with an error of four nautical miles. The temptation is to leave it and fudge the details a little to conceal its presence, but I suspect there was something in the missing page of voyage notes that explained the discrepancy so I am hunting though my sources to find more information and rereading all my notes, including the modern sailing directions for the Caicos Passage.
Wish me luck