[don1reed]

I've been down this path before, also.

Here's what I've discovered.

1) The F5 chart screen is not accurate due to x/y ratio. (it's just eye candy for dragging and dropping a course.)

2) I've tried sailing Great Circle courses and Rhumblines as plotted on real charts, using Omar Reis's computer NAVIGATOR program running in the background and use a Texas Instruments TI-86 with onboard Naviation program from StarPath School of Navigation; in both cases the course being true on a real chart, comes no where near the destination on the SH3 F5 chart.

3) Both of my real navigation programs have ephemeral celestial data for the war years and although the celestial canopy is 'purty' in SH3 it is nowhere near accurate. The Moon is also...just eye-candy with some correct phases. for good measure.

4) A real Kriegsmarine chart for the Nord Atlantischer Ozean has planquadrats that are 'squares' up to about 50°N, where they start to become retangles with a longer vertical aspect rather than what they look like in SH3, longer horizontally. This makes it difficult to determine one's Geo Coord due to the distortion of the Mercatur projection.
-...-

One could still navigate with compass sailing alone. Just don't use the course plotter. You can use the ruler to draw lines (rudimentary course)...then try...try to follow them with compass sailing alone.

Once you plot your course route from point A to point B, Zoom in on the F5 screen so you can no longer see adjoining land masses. Sail by compass and D = ST.

You'll find that storms and other internal forces wiill cause your boat to ... drift.

One other thing...

keep your TC to no greater than 128

Edit: You could also update your location plot only while surfaced (simulating sextant usage, and then, only on cloudless days/twilights)

A good test would be...

just prior to starting a patrol, use the ruler to measure courses and distances to the assigned square, jot them down then erase them from the F5 screen. Zoom in on the F5 screen to where you can see your boat or at least where the little squares show up, then begin your patrol, trying to navigate there and back with compass sailing and Distance = Speed x Time alone.

cheers,