Advance
Oak Forests for Ships
The more punishment our ships can take, the more they can dish out. Let us ensure that we have a ready supply of the finest seasoned oak for our warships.
Advance tree
The game files don’t say where this goes: it has no requires, so the game places it in the 
Discovery tree itself.
Modifiers
Heavy Ship Power+20%
Definitionin_game/common/advances/4_choices_mil.txt:172
174icon = rudimentary_coastal_ship_repair
175for = mil