sentences:  Next August both first boats entered official trials, and while several requirements were not met (for example, speed was 0.5 kt (0.9 km/h, 0.6 mph) lower than the specified 20 kt {37 km/h, 22 mph}) and there were some technical difficulties, the project was considered successful and the boats were commissioned into the Soviet Navy.The third boat, while still using other German machinery, was powered by Soviet-made diesels, due to delays in delivery of originally intended ones.However, adaptation to significantly different domestic engines required significant redesigns that slowed construction.