GPS Backup with a Mark 3 Sextant

Our guiding principle for this booklet was to provide a means of learning and executing a position fix at sea when a vessel has run out of power and all the batteries have been consumed, so there is no GPS available. We wanted a solution that is compact and inexpensive, using tables and procedures that are easy to learn and use. This goal led to our proposing a minimum kit that mariners would not hesitate to add to their gear to cover the unlikely situation it would actually be needed. Mariners who cross oceans in small boats realize they must be self-reliant and cover all contingencies.

For those who choose not to invest the time and money to learn the full range of celestial navigation, this booklet and a Mark 3 sextant provide a minimum backup kit that can be used to navigate across any ocean if needed.