I think, more than any other potential feature, charted navigation aids such as lighthouses would boost the realism of maritime navigation beyond anything else available in a publicly available sim / game today. Not even Ship Simulator gives the user the tools needed to adequately simulate marine navigation. Not that this takes away anything from Ship Simulator. But that game's focus is on ship handling in harbor, not trans-oceanic navigation.
In the mean time, in many cases you can still navigate using edges of land. Just pick three visible points of land more than 10-15 degrees apart each other and take some true bearings. The point where the three lines cross is where your fix is. If you get a "cocked hat" (small triangle instead of a perfect point) then plot your position inside.
I'd like to see if there is a way for SH to plot the ship's position within a circle of uncertainty of say 3-5 nm at an interval of something like every 24 hours at noon, or near sunrise and sunset, simulating the results of an astro fix taken by the ship's navigator. Obviously cloudy weather would make this feature seem a little unrealistic. Regardless this would force the skipper to DR his way around the ocean without having to do all the "extra stuff" required to get an astro fix.
I'm the Captain. I don't need to use a sextant. But I do make decisions based on the best position information available.
And don't forget, depth contours can also be useful wayfinding tools. Take a line of bearing and ping your depth. Then look at your chart to determine the most logical place where both coincide. Doesn't work everywhere. But some places have steeper contours than others.
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