Sextant? I think we are long past the sextant era.
Bringing a sextant (very expensive) requires all the appropriate books (very expensive) and the knowledge to do the calcs.
I'll take a boatload of GPS receivers first. Cheap, no books, no calcs, better accuracy, works in all lighting and weather conditions.
There is a tide in the affairs of men,
Which, taken at the flood, leads on to fortune;
Omitted, all the voyage of their life
Is bound in shallows and in miseries.
Shakespeare, Julius Caesar IV, iii, 217