Complex sentence: The ship's crew temporarily shifted their administrative homeport to Baltimore and began an extensive four year service life extension project, with significant work planned for the main diesel engine, the HVAC systems, additional engine room equipment, the hull, and numerous other systems.
Split into simpler sentences: The ship's crew temporarily shifted their administrative homeport to Baltimore and began an extensive four-year service life extension project. Significant work is planned for the HVAC system, engine room equipment, the hull, and other systems.