ESPECIALLY Luo Yan. Luo Ren saw how decisive he was. Not only that, he was also very quick on his thinking and judgment. Just by listening to the song that suddenly sounded in the ship, he immediately recognized that it came from mermaids and they were most likely the next trial on their journey.
He didn't hesitate to wound himself and Luo Jin just so the two of them wouldn't fall under the influence of the mermaids' voice. In just a few seconds, he already knew what he was going to do next. He went to the wheelhouse of the ship without a second thought. As if he already knew what's going to happen if the mermaids continued their singing.
Luo Yan most likely applied the common myth about mermaids that's why he the first thing he thought was to go to the wheelhouse. Luo Ren understood that choice. Because mermaids usually equaled to shipwrecks. If no one stopped the ship, then it would most likely capsize.