Upgrades for ships in the shipyard could be used to make a certain ship more attractive to buy. Since the upgrades cost more than the ship it might be a way to get a better ship without having to wait until one has much more money.
The reinforced hull and copper plating are the only ones I can think of that are not simple addons that can be done quickly.
The reinforced hull and copper plating are the only ones I can think of that are not simple addons that can be done quickly.