Celestial Navigation? Forget it!
I agree with the premise that sole reliance on electronic navigation equipment is a dangerous (and foolish) approach to seamanship.
Jeff & Tsenator are right on.
The gov''t isn''t about to announce in advance when it''s going to degrade the GPS signal.
For coastal cruising, familiarity and basic competency with chart reading and plotting, compasses, tidal analyis and dead reckoning are some of the hallmarks of sound seamanship. Being comfortable without a GPS on board should be the goal.
CN fits into the picture for offshore passagemaking. I sure would want someone on board who is competent at CN.