It's not the spanker model that determines its direction, but a locator value.
In the mast model which supports the spanker, find its locator and change the XX value to -1.
That's what changes the direction, because it literally inverts the model along the x-axis, which turns it inside-out.
Some ships, however, have the damn thing modelled with a yard stuck to it, as part of the above sail.
In that case, changing this locator value would cause havoc, so the spanker needs replacing, and another yard added separately.
Believe me, I've tried all possible combinations of XX, YY and ZZ values, but all others just give upside-down, wrong way around, stretched, squashed, or otherwise distorted results. :wacko:
I've also tried positioning the model at an angle using TOOL, similar to the Lugger's spanker, but that just keeps the spanker on one side of the ship at all times.
So this is the only way, and to remove the reverse lighting side effect, the model needs to be physically inverted, so that the XX value cancels it out.