Final answer:
To determine how many feet of anchor line to let out, add the height of the bow of the boat and the depth of the water.
Step-by-step explanation:
In order to determine how many feet of anchor line to let out, you need to consider both the height of the bow of your boat and the depth of the water.
Since the bow of your boat is 3 feet above water and the water is 10 feet deep, you need to add these two measurements together to find the total distance to the bottom.
So, you would need to let out 13 feet of anchor line.