Could I get a verify that, as implied, retooling to build a 'slightly better' version of a ship ("We swapped out the old Mark II missile launchers for the new Mark IIIs") will take a lot less time than retooling to build a completely different ship of the same, or close, tonnage? That is, if Ship A uses 3 type-4 ion drives, and Ship B used 3 type-4 ion drives, the part of the shipyard that assembles and installs type-4 ion drives doesn't need to be retooled and doesn't count, or counts less, against the cost of retooling? Or, in other other words, is retooling 100% based on the hull size of the ship, or is it based on how many components the ship shares with the prior ship?
This is pretty important, as it could effect which yards I retool, and why. I was going on the assumption that it took just as long to retool from the Exeter Destroyer to the Exeter-A Destroyer as it did from the Exeter Destroyer to the Franklin Geo Surveyor, if both ships were the same overall tonnage, so it didn't matter what a shipyard was previously making.