ThinksMarkedly wrote:It's not prohibitive, it's just not cost-effective. The refit would cost too much for obsolete ships. Don't forget that refitting also takes slip space, something they could be using for building or fitting out a brand new light cruiser or destroyer. So you have to add the cost of opportunity to the equation too. My guess is that it simply wasn't worth it: if you had the build slip, the budget, the personnel, and materials available to perform the refit, you'd simply instead do something else with those, for a more practical gain.
In fairness space isn't water, you don't actually need a proper drydock for construction purposes. So that's actually the EXACT reason you'd employ Grayson style yards. Which when building a brand-new ship is merely just enough framework to anchor your construction crews something to tether to.
If you're refitting literally anything, you don't really need a full-up construction slip especially if it's a low-priority refit, such as adding TWTMNBN to sub-capitals. Put the ship a short distance away from anything, or from an 'open-to-space' supply depot, assemble a minimal frame around the ship, and away you go with refitting. You could refit hundreds of ships simultaneously with standalones, while reserving your proper slips and their far superior time-to-efficiency rates for new construction.
Although in wartime you'd probably reverse that, and exclusively use standalones for new construction and reserve slips for repair and refitting. You'd minimize the time a ship is out of action for, while you simultaneously build far more brand-new ships than you have total slips.