NavList:

A watch (or anything else) at sea in a small boat is going to be in constant motion, sometimes violent motion. In my case for 29 days, from the mouth of the Delaware River to the Azores. It's a pretty random motion, so I wonder if the effects wouldn't all wash out over time. I guess the only way to find out would be to actually track the rate during the crossing (which I wish I'd thought of doing, now that I think about it!) 

I did periodically check the two quartz watches I was using for navigation, and they did not seem to be affected by the motion. I had drawn up an 'error correction' chart for each watch before departure, and including the error correction, they were correct to the second on arrival in the Azores. 

I may just invest in a mechanical watch to play with this summer. I say 'play', because it's all for fun, afterall. Good fun, though!