[Tanus]

I think that Gandalf is speaking of a normal retroseries build scheme.

If you have the extra resources such that you can pay for it, with a retroseries Gandalf would have a stronger fleet.

Take 30 shipyards;
If you build complete ships, and each ship takes say 6 turns, then you'll have 30 complete, top-of-the-line ships in 6 turns.

If you retrobuild with a 2 step process, you could have your first shell ready in 3 turns.
So in 3 turns, he has 30 basic shells
by turn 4, has 30 midway shells
turn 5, 30 complete, top-of-the-line ships
by turn 6, 30 complete ships and 30 basic shells

So he now has 60 ships to your 30, and his production will continue to outdo the full-build style.

by turn 12 (full build has 60 complete ships), retrobuilder has 90 complete ships and 30 shells

I hope that helps