Taiwan's first home-built submarine looks set to miss its delivery date again, a setback for the navy and for the island's defense plans.

• The Hai Kun has only two sea trials left, but it has not gone out to sea since late July.
• The sticking point is the side-scan sonar, which cannot pass its data to the combat system.
• The sonar maker will not take on the system hookup, and the domestic research institute does not have the know-how to fix it — so nobody has found the cause.
• Earlier trials went badly: the boat dove less than 100 meters, water flooded an engine after pipe changes, two of its four engines are still untested, and there are leaks.
• Former navy adviser Kuo Hsi warns against a "fake handover" — signing the boat over on paper just to hit the date.

Outlook: Delivery by the end of this year looks out of reach, and the shipbuilder is staying silent on the accusations.