Secret meetings are often the precursor to a big trade or a big action. It is likely that something when down and that Lionel Messi will be moving to Chelsea soon. This would be a big worry for Barcelona fans, as Lionel Messi is one of Barcelon's best players, and the team will not be the same without him.
No, there really isn't anything to worry about just because two powerful members of the soccer world met on a yacht. Lionel Messi's father may simply have wanted to meet with more members of the soccer world when he met with Chelsea's owner. There is nothing to say that this meeting even had any professional motives. It could have been purely social.
There are twenty teams in the top league. Twenty owners, four hundred players and around eight hundred members of personal family and friends. This is a small circle who do understand each other and know each other. It's only natural that these people would socialise together but that's not a valid reason for us to start conspiracy theories!
No, Barcelona fans do not need to be worried about Messi's dad meeting with the Chelsea team owner. Messi's dad meeting with Chelsea owner on a yacht does not necessarily mean that Messi is leaving the Barcelona team. It is plausible that Messi's dad has a relationship with Chelsea owner outside of his son's soccer career.