I managed to get the first ship i produced to level 41 along with all the other ships in the fleet (same type)
it was a small hull
3 railgun mk IVs
and 1 impulse drive mkIII
at level 41 it had 76 hp the engine techs had increased its speed to 6 parsecs/turn and a fleet of 5 could take down an enemy frigate with a standerd set of fighters (i had more but my logistics ability wasnt the best at that point) i didnt farm them up to that level i just used them normaly replaceing the ones that lost and bringing the most wounded ships to a nearby planet to recover when they were low on health i no longer was useing them midway through the game because they stood no chance against the newer ships