You're taking Bintan Resort Ferries, I presume? All bets are off if the weather is so bad that they start cancelling, and we are in the monsoon season, so you'll want a Plan B if you miss your flight. That said, BRF is usually pretty punctual and TFMT is reasonably efficient, although joining the scrum to exit the boat first on arrival won't hurt. Taxis can also be in short supply, so you'll probably want to call one (numbers are posted at the taxi stand).