# Frostbite Theater

Here's a Question! - Boat and Anchor (Part 4)

A boat floats calmly is a partly filled aquarium. The boat's anchor is thrown overboard but, due to shoddy construction techniques, it does not reach the bottom of the aquarium. What happens to the draft of the boat?

Announcer: Frostbite Theater presents... Cold Cuts! No baloney!

Joanna and Steve: Just science!

Joanna: Hi! I'm Joanna!

Steve: And I'm Steve!

Joanna: Here's a question for you...

Steve: A boat of dubious construction floats calmly in a partly filled aquarium.

Joanna: The boat's anchor is thrown overboard. But, due to shoddy construction techniques, the rope attached to the anchor is too short for the anchor to rest on the bottom of the aquarium.

Steve: What happens to the draft of the boat?

Joanna: Does the boat rise up, which decreases its draft?

Steve: Does the boat settle into the water, which increases its draft?

Joanna: Does the draft stay the same?

Steve: Or, does it depend on how deep the water is?

Joanna: Pause the video now if you'd like to think it over before we show you what happens.

What happens to the draft of the boat if the anchor doesn't reach the bottom of the aquarium?

It decreases.

Steve: The boat floats because it displaces a volume of water with a weight that's equal to the weight of the boat.

Joanna: Since the anchor doesn't come to rest on the bottom of the aquarium, the total weight that's floating doesn't change.

Steve: But, the anchor itself displaces some water. This is water that doesn't have to be displaced by the hull of the boat.

Joanna: Since the hull of the boat doesn't need to displace as much water, it rises up, which decreases its draft.

Joanna: Thanks for watching. I hope you'll join us again soon for another question!