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True Rhumbline Distance (WGS-84) Calculations

By Captain Dr. Ivica Tijardovic


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We are pleased to announce that this book is available in a digital format from the following suppliers:

Bogerd Martin : Chart Track NavReader 

Marine Society & Sea Cadets : MS SeaReader

Navtor Nautic : Navstation

StormGeo : s-Planner | Publications

Todd Navigation : SeaReader

Weilbach : WENDIS SeaReader


In 2000 Dr Tijardović published the article Rhumbline Distances in Journal of Navigation, Cambridge after conducting a large research project on GPS accuracy - where he found out that none of 25 GPS receivers calculated accurate distance. In 2004, Brown's Nautical Almanac introduced True Rhumbline Distance and since then Transas ECDIS and Admiralty Navpac IV have been using True Rhumbline Distances in their software.


The only way to get the accurate Rhumbline Distances is to use the True Rhumbline Distance (WGS – 84) calculations, otherwise the GPS or the ECDIS Rhumbline Distance may differ from the accurate by one or 2 miles (between Miami and Charleston), 15 miles between San Francisco and Australia and more than 40 miles between Philippine and Panama.


True Rhumbline Distance (WGS – 84) Calculations is for everybody who uses the GPS and the ECDIS at sea. Mariners, officers, yacht and sail boat captains; and particularly students who may use a simple technique to calculate the True Rhumbline Distance by a calculator with trigonometrical functions.


Whoever has a GPS receiver or ECDIS may use the Tables to see how much the GPS or the ECDIS Distance differs from the True Rhumbline Distance.


True Rhumbline Distance (WGS – 84) Calculations should be a standard for the Officer of the Watch exam and students of Nautical science.