ORIGINAL: Cap Mandrake
Pretend I didn't read the manual.
Why was I unable to reload main gun ammo on Nevada at Wellington with a level 5 port and 30 naval support points, even with a loaded AE in support?
As others have noted, size matters....to a certain degree only. Next time the lawyers argue over clauses in the pre nup you can impress them with your knowledge of s.20.1.2.2 of the manual. The abridged version is as follows.
As the Nevada's rifles have an effect of 1500, they can only be rearmed where you can generate 3000 rearm points (ie 2x the effect of a weapon). The native rearm capacity of a port is provided in the table on page 109. From here you can see that a port sized 5 has a low rearm limit of 300 points, far below that required to allow rearming the Nevada.
You can supplement the native rearm capacity of a port with Naval Support squads. Each Naval Support squad provides 5 rearm points. Hence your port sized 5 would need 540 Naval Support squads to make up the deficit. With only 30 such squads at Wellington, you are well short.
Use of tenders can bypass deficient sized ports and Naval Support squad shortages. In the case of the Nevada, all AE classes and all (excluding one) AKE classes, if fully loaded, can fully rearm the Nevada. The one AKE class which cannot fully rearm the Nevada, is the Regulus class as it's total capacity is only 2560 points. Of course, if you had any other AE/AKE class present at Wellington but with less than a full load (specifically less than 3000 supply points on board), you would not be able to rearm the Nevada.
In summary, a size 7 port will fully rearm the big guns of any Allied BB. A size 6 port will rearm the 8" guns of any Allied CA, a size 5 port will rearm the 6" guns of any Allied CL. There will be very few Allied ports which will have present the necessary hundreds of Naval Support squads to make good for a "small" port. This is why fully loaded AEs/AKEs are so valuable, but remember the small size of the Regulus class which really relegates it to rearming Allied CAs.
Alfred