Thanks Makman. I've installed OLC and the x6 magnification mod you linked. I haven't used the OLC mod before so I'm not completely clear what additional functionality the stadimeter mod provides. I think it adds a stock SH3 notepad style stadimeter and modified periscope ranging rings tweaked to use doubled mast heights, is that right?
That's very nice but the notepad is still only showing 1 decimal place of accuracy in the stadimeter angle readout which is not good enough for long range shots. I can see that the notepad uses a more precise calculation in the background that in theory enables you to get the required accuracy, but the notebook uses mast height values from the ship recognition manual some of which I suspect are wrong. What's really bugging me though is that on the periscope while the stadimeter is activated the only vertical scale appears to bear no relation whatsoever to the angle measured to one decimal place by the stadimeter notebook.
http://img147.imageshack.us/my.php?image=stadi.jpg
If the stadimeter could be made to provide a more accurate angle readout (either on the notebook by an extra decimal place, or via adjusted periscope markings) then I don't think it's actually all that much work to fix the mast heights. The only posts I've read here that have considered that issue seem to have assumed that the fix would consist of exporting the models and loading them into a CAD package, measuring them and resizing the masts, which would of course be a total ball ache.
But wouldn't a far simpler fix be this? Improve the stadimeter to provide an accurate angle measurement. Load the game with the chart in God mode and then you can measure the exact range to a target on the chart and use the stadimeter formula 'range = mast_height / sin(theta)' in reverse, and use the known range to calculate the actual correct mast height. I believe it is then a relatively simple matter to update the config files for the ship recognition manual with the corrected mast heights.
It may not be the historically accurate approach, but an accurate range determination is so critical to the game that for me a little historical inaccuracy about the actual mast heights would definately be a price worth paying.
I can think of another way to do it too by calculating the amount of error in a range measurement and working back from that to the mast height error. But I only installed SH3 a few days ago and so far I've only run couple of missions. It did seem to me though as if I was repeatedly taking good measurements that were consistantly out by a fixed amount, and a more accurate readout of the raw stadimeter theta angle would really help narrow down the cause.