Hey Fishlord. Those aren't sugar boats!:rotfl: One is a Salmon/Tambor class and the other a Gato. You can't turn one into the other, you must be issued a new boat from construction for that to happen.
Upgrades are offered on a merit basis, but there is a random character to it. Some great perfroming skippers aren't offered because of a bad roll of the dice. You can maximize your chances of being offered upgrades by NEVER refitting and continuing the same patrol, unless you're just extending your range to get back to base.
The more patrols you take, the higher the chance you'll be offered the new construction or rebuild options.
Have you given up on the sugar boat? If so, I don't blame you. The Gatos and above are sweet boats. If the sugar boats were so great they never would have built something better.
