🔍 Key Concepts

• How a marine chronometer is used for navigation and why consistent timekeeping is critical • The effect of letting the mainspring run down on time accuracy • Typical daily maintenance routines aboard ship for critical navigation instruments

💭 Think About

• Think about how often you normally take care of precision instruments that directly affect your position calculations—would you wait several days? • If the rate of the chronometer (gain or loss per day) is to remain very steady, how frequently would the spring tension need to be kept nearly the same? • Which choice best matches a practical routine a navigator can reliably remember and perform without skipping?

✅ Before You Answer

• Consider which interval best keeps the mainspring tension nearly constant • Ask: Which option fits into a regular daily navigation routine (log entries, position fixes, etc.)? • Eliminate options that would let the chronometer run too long between windings, increasing risk of rate changes or stopping