Go to gauge > other gauges... menu item. Select the required new gauge/scale on the list. Click the convert group button above the list. If you haven't created a group of templates, you will have the option to group all of them for the conversion.
Unfortunately it is not mathematically possible to do a perfect conversion unless the gauge:scale ratio and the gauge:flangeway-gap ratio remain the same. In practice this means only the proto gauges convert closely: S7 - S - P4 - Proto87 - S2 etc., and even then there may be some tiny differences.
For other gauge conversions there are likely to be some slight mismatches, overlaps or gaps between the pointwork templates which need tidying up. But usually this is much quicker to do than starting again from scratch.
The plain track templates will always convert exactly, so these shouldn't need changing and make a useful guide in re-adjusting the pointwork templates to fit.
If you change the scale, and you have used a background map or scan as a guide, note that this will need scaling up or down to match the new model scale.
First on the background shapes dialog, on the picture options tab, change the scaling lock option to grid. Then select the picture shape in the list, and on the modify shape tab, click the scale by... button. Enter the required percentage change as: new scale in mm, multiplied by 100, and divided by old scale in mm. Click the ? info button and read the notes.
Remember to save a fresh .bgs file afterwards.
For example, converting to N gauge from EM:
N scale (UK) is 2.06mm/ft
EM scale is 4mm/ft
So the percentage change needed is 2.06 x 100 / 4 = 51.5%
if you have changed only the gauge and not the scale, for example 00 from EM, there is no need to do this.
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