NavList:

Hi David!

I've been meaning to respond to your question on the Cruiser's Forum - but something always seemed to come up that distracted me before I could compose a decent response. Also, I don't know if there is much more useful information I can add to what GrowleyMonster wrote there - or what Murray wrote here.

I did mean to ask what your actual goal is. On CF, you wrote:

"Referencing my old notes to calculate 'declination' and because of my laziness found this gizmo that perhaps will save me a fraction of a minute to open and read the tables."

and

"when I say not interested on deviation,I mean only in my narrow question regarding the use of the sextant to determine Lat, we all know the importance to correct for deviation when using our paper charts."

Since this was in a thread about a sextant app, my first thought was that you might be trying to find the declination of a celestial body. If that is indeed the case, then a compass of any kind will not help you. "Magnetic declination" (or "variation") and "the declination of a celestial body" are two entirely different things. If you want to find the declination of a celestial body at a given instant with any reasonable accuracy, then you will have to use tables or a program/app of some sort.

On the other hand, if you want to find true North as opposed to magnetic North, you can probably get by with looking at a relatively recent nautical chart and applying the correction given in the compass rose (plus the yearly correction).

So if you can explain what, exactly, you are trying to achieve ... then everyone on CF and NavList will be in a much better position to give you the help you are seeking.

Cheers!

Sean C

a.k.a. SeanPatrick