Complex sentence: Firstly, the planned structural and spatial improvements for the area were stopped.The competent authoriries refused to grant a certificate of seaworthiness to the new vessel demanding expensive and unpractical changes to the ship to bring her up to modern standards.
Split into simpler sentences: Firstly, the planned structural and spatial improvements for the area were stopped. But The competent authoriries refused to grant a certificate of seaworthiness to the new vessel demanding expensive and unpractical changes to the ship to bring her up to modern standards.