How was SpaceX able to keep the rocket from tipping over on the barge?

Question

How was SpaceX able able to keep the rocket from tipping over on the barge once it landed? The barge looked like it was rocking quite a bit.

Answer 1

The center of gravity of the first stage is much lower than it would appear at a glance. The stage is mostly empty fuel tanks, which are very light; the engines and landing legs are the heavier components, all very low on the stage.

If you mentally visualize the rocket body as being only about half its actual height, you'll have a much more accurate picture of the weight balance of the stage, and you'll see that the rocket is unlikely to tip over.

After the landing, my understanding is that another manned sea vessel will meet up with the barge, and workers will either install support chains in a "guy wire" configuration, or weld "shoes" onto the deck over the landing legs, or both, which will keep the stage stable in case of rougher seas on the trip home. That support vessel keeps its distance during the landing itself for safety reasons.