I cannot give the boatman in rain the doubloon. I have tried getting the doubloon and then talking to him which apparently bugs. So I started again and talked to him before I got the doubloon which also doesn't work out. Exactly when am I supposed to talk to the Professors at Gno to make this work? I am supposing that I have to talk to him.

Which old man am I supposed to talk to? I looked through most of the library and I cannot find one.

Basically, how did everyone else do it?

Also, does anyone have any save games directly after this point?

I can give you the following steps, if you still require aid:

1. After getting the Ice Orb, a runner comes in and informs you that the professors have clues for your search.

2. At Gno, talk to all three the professors, just to be safe. The two on the stairs will explain how to get to Spire. They give you a chant to summon Thaddeus.

3. Proceed through the game until you get to the tavern. In here, do everything and buy everything, including the cursed doubloon from the captain at the bar.

If everything has been done, then the boat man will accept the cursed doubloon as payment and ferry you to Thaddeus' tower. From there a cutscene will play out, and after that you can enter the submarine to go to Spire.

I hope this helps you, as this method works for me every single time. I suggest checking these steps, and if it isn't working, try the steps in order on a new game or earlier save.