To prevent dehydration while on the water, you should drink some water at least every:

Staying hydrated is crucial for safety and comfort while boating, especially under the sun and with the wind and water influences that can lead to dehydration. Drinking water at least every 15-20 minutes is recommended because it helps maintain optimal hydration levels as physical activity often causes increased perspiration and fluid loss.

Frequent hydration prevents conditions such as heat exhaustion and heat stroke, which can occur more easily when exposed to high temperatures and exertion. The 15-20 minute interval is a balanced approach that allows for regular fluid intake without overwhelming the stomach while still being frequent enough to maintain hydration.

The other options suggest intervals that are either too short, which may lead to discomfort or overconsumption, or too long, risking dehydration. Regular intervals are particularly important in outdoor settings where environmental factors can exacerbate fluid loss.