To maximize the number of people, assume each person weighs the minimum possible weight: \( 53 \ \text{kg} \).
Let \( n \) = number of people. The weight constraint is: \[ 53n \leq 630 \]
\[ n \leq \frac{630}{53} \approx 11.88 \] Since \( n \) must be an integer: \[ n = 11 \]
\[ \boxed{\text{Maximum number of people} = 11} \]