Great Circle Sailing A B C Method

[Greg D]

Hey everybody hope iv posted this in the right place

Im having a little trouble with naming A and B while doing the A B C method for nav maths. I know that in cel nav A is named the opposite to latitude except when the hour angle is between 90-270 degrees and B is the same as declination. does this mean that B is named the same as the direction the vessel is moving in terms of latitude?

all help is greatly appreciated
thanks in advance

[Lewis]

a is opposite to latitude you start at unless dlong is between 90 and 270
b is named after the latitude you are sailing too.

[Greg D]

cheers mate

[Lewis]

Remember GHA and Declination are just positions. If Your lat and long matched the Declination and GHA of a celestial object it would be right above your head. Only difference is GHA goes west all the way round to 360 not west and east like longitude.