What is a purpose of ballast and ballast tanks in boats?

Ballast and ballast tanks in boats are primarily used to add weight, which enhances a boat's stability and balance, especially during various activities such as water skiing. By strategically placing ballast, a boat can achieve a lower center of gravity, which helps it remain upright and reduces the likelihood of capsizing. This added weight is especially important in water sports where maintaining stability is crucial for safety and performance.

In the context of other options, reducing speed while racing is not a goal of adding ballast; rather, it can sometimes slow a boat down due to the extra weight. Storing fuel is not a function of ballast tanks, as they are specifically designed for weight distribution rather than fuel storage. Lastly, controlling engine temperature is unrelated to ballast; engine cooling systems address temperature management, while ballast deals with stability and buoyancy.