@pixel_player376259257 @CynthiaF There really isn't an option but to take your time upgrading Titanic.
If the Coins and Wood required didn't make you wince, then research the XP you gain each upgrade. This will make you sit taller in your chair and tighten your Sphincter muscles.
I currently have enough coins/wood to upgrade to 4th Star and 5th star (6th and 7th are easily accomplished with Chevrons), but the XP gained will propel me 19 levels. Some may see that as a positive, I see it as something that needs to be stage-managed. 19 levels is 3 TownHalls, 60 (ish) building upgrades) plus 6 Main Docks.
Great way to fall behind and as is evident, not easy to catch up from.
It is for these reasons that Titanic is such a trophy. It is almost a game within a game. Some have even said on this forum that your fleet is incomplete without it.
Easy to buy it., yet takes a skill to upgrade it without buggering up the rest of your game, do it too soon then you compromise everything else.
Oh, and if you do manage to pull it all off, as Cynthia alluded to; Not only does it sit proudly in your fleet, it can serve you for a very very long time.
It's the Mayfair in Monopoly, not the best value, but maximum bragging rights !