Imported submarine designs became a Russian construction portfolio

The submarine survey shows Russia using several routes to acquire a new technology. Karp-class boats were built by Krupp for the Imperial Russian Navy, while the Kaiman class used an American Simon Lake design but was constructed in St Petersburg. Other early classes and one-off boats filled out a varied experimental force. This portfolio spread technical ideas across foreign designers and Russian yards rather than relying on one national school. It also provided the experience from which a purpose-designed domestic minelayer such as Krab could emerge.