When i had a ship that was of the same hull size and it had taken some damage and i upgraded it to a later model of the same ship the HP went into the negative on the ship that i was upgrading but it stayed alive because it was in a fleet. But when i dispersed that fleet the ship suddenly vanished in the middle of the upgrade. I have no idea why this happened but it obviously did.
So, if you have 10 ships in a fleet of X MK1 and one of them has 1 hp left and you upgrade them to X MK2. Then the one with the 1 hp will die. OFcourse assuming that you've gained levels on the one that has 1 hp left so it has more base HP now then the upgraded model which isnt corrected for experience levels.
Anyone else seen this?