Mustering out with a ship (25%)
Does that reduction go to the mortgage payment or the mortgage period?
Is it 30 years of payments at 100%?
Or 40 years of payments at 75%?
I guess you're talking about MgT2E, as in 1E the ship benefit (scout excluded) is 5 shares to a spedific ship or 2 to naother one...
Time, so it's first benefit 40 years, second benefit 30 years left, and so on.
I'm afraid this was in CT. In MgT2E things are a little different (Main Book, page 45):
Free Trader: ou receive a free trader with 25% of the mortgage paid off on it.(...) If you roll this benefit again, an additional 25% of the mortgage has been paid off.
So, first roll is already 25% paid, and 4 rolls is the ship free.
As an aside, see that in page 142 (again Main Book), under "Buying a ship", no reference is made to the CT down payment (20%), only talking about the monthly mortgage cost...
About the OP question, if this 25% is in time or in montly mortgage repayment, if this is specified I cannot find it.
If you asume this menas already 10 years paid off, then the ship is 10 years ols per roll, and 10 years have already been paid (as in CT).
OTOH, if you asume this means ship shares worth 25% of the ship price, the ship could well be Brand new and the initial payment (represented by the ship shares) be 25% of it, so reduced from the montly mayments for the standard 40 years...
As this is not specified (or at least I didn't find it, maybe in latter books I don't own), I'd let it to the GM (or player) discretion...
Of course, YMMV...