What could explain why it took Magellan 38 days to navigate the strait

There are two main reason why ti took Magellan that long:

- First, he had to face the scrutiny that initiated by the spanish captain in his ship, so he had to waste several days in dealing with it

- second, the strait pathways is far more treacherous that what Magellan had imagined, making it really hard to navigate the ship.