Tony B
Guru
- Joined
- Jul 18, 2011
- Messages
- 1,251
- Location
- Cruising/Live-Aboard USA
- Vessel Name
- Serenity
- Vessel Make
- Mainship 36 Dual Cabin -1986
I have some issue with the statement "First, a definition is in order. Dead reckoning is the process of estimating the position of an airplane or ship based solely on speed and direction of travel and time elapsed since the last known position (or fix). So all you need to figure out approximately where you are is an airspeed indicator or log or other measure of speed, a clock or watch, and a compass."
I was taught DR was the initial 'plotting' of a course. You grab a chart, mark off your current position and your intended destination. Draw a straight line between the two and you should be able to determine your course and diatance. Once underway, you can calculate your ETE for any given speed. DR does not take into account things like wind speed and current. That is DR - plain and simple. With DR, your course and heading are the same - which rarely happens in the real world unless on a small lake with no wind or current
Once you start accounting for 'set and drift', you are no longer DRing. You are navigating by known parameters.
Anyway, this is what I was taught in Sea School in the land that time forgot.