On 5 Mar 2017 at 9:02, Jeffrey Schwartz wrote:

> There is very, very limited ocean travel - Sailing ships on the trade
> winds that are pretty regular, but navigation is a bit freaky with no
> good clocks and no noon-sun shoot.

Actually, shooting the sun will tell you how far from the "noon pole"
you are. That places you on a circle. Call it solar latitude.

Since the planet *has* to have a magnetic field to be habitable
(don't ask how it maintains it) because of flares from the star (red
dwarves are prone to flares), comparing the direction of the sun with
north, places you at one point on the circle.

It won't be nearly as accurate as what we are used to, but it'd
likely place you within a few dozen miles. Not great for avoiding
reefs or the like, but usable for a rough idea of where you are.

The solar latitude will be a lot more accurate than the "magnetic
longitude". So you won't have a circle of uncertainty in your
position. More of an ellispe with the long axis running along the
line of solar latitude.

--
Leonard Erickson (aka shadow)
shadow at shadowgard dot com