Complex sentence: In 1928, "Majestic" was extensively refitted and modernised and enjoyed a boom year for passenger lists, but numbers fell slightly in 1929 and then the Great Depression set in by 1930.
Split into simpler sentences: In 1928, "Majestic" was extensively refitted and modernised and enjoyed a boom year for passenger lists. But numbers fell slightly in 1929, and then the Great Depression set in by 1930.