To answer your question directly. A mechanical timepiece that calls itself a marine chronometer has to be accurate to +-0.5 seconds per day. The most accurate

To answer your question directly. A mechanical timepiece that calls itself a marine chronometer has to be accurate to +-0.5 seconds per day. The most accurate quartz wristwatch is certified accurate to +-5 seconds per year. My experience, in the exact harsh real world conditions that you are talking about, is that is a realistic expectation for quartz watch to accomplish. I cant imagine why an instrument that is ~40x less precise would offer more precise timekeeping