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Hanno,

Thanks. Frank is right of course, in a logical way. And his work and web site is the the best.

Yes, I enjoy doing long hand Doniol for Hc and probably now TS,( I'll test it in a  few days) and also old 19th century logs/haversines. No particular reason other than enjoyment. Also enjoy slide rules and therefore do that. No logical reason for doing any of this with 1 button press GPS to nearest 1 meter!(and my GPS has never  (yet) failed me. Also love no -clock lunars to nearest 10-20 nm! (but take a sneaking look at the GPS/e Chart plotter,) especially if close to rocks near the Scillies and HMS Association! (have sailed over her and dived on her  several times! But don't want to join her!) 

All good fun really. But keep the GPS chart plotter , radar etc on , just in case! For me this is mostly for fun. Just wish I had more maths! Slowly getting there in my old age. (good at medicine and biochemistry, barely able to cope with the maths of my main old age  obsession!). Just loved  coming home safely over  a hundred miles of ocean with just  Polaris and the milky way over the bow and nothing else! Magic!

Thanks to all you lot for keeping my enthusiasm going. Good stuff.

Francis