I assume you have seen this information from a
broker BuySellBoats - Footloose Cruising Yacht for sale - gives
designer,
builder, etc.
I also assume that you have noticed that the stated 15 tonnes
displacement is VERY heavy for a 12m
steel sail
boat. A weight
budget would normally be 10 - 12 tonnes with empty
tanks, etc, with 12 tonnes being at the very heavy end for 12m x 4m beam boat. You mention 6mm plating for the
hull in your
mast bend thread and that will be part of the weight problem, 6mm being 50% thicker than the normal 4mm for a 12m sail boat.
But looks a nice well equipped boat for all that.