Mosiah 10:14

And his brethren were wroth with him, because they understood not the dealings of the Lord; they were also wroth with him upon the waters, because they hardened their hearts against the Lord.

His brothers were angry at him because they did not understand how God works. They were also angry at him on the boat because they would not listen to the Lord.

Nephi’s brothers were furious with him because they didn’t understand how the Lord worked. They stayed angry at him during the ocean voyage, because they’d hardened their hearts against the Lord.