Reverse-engineering a Type IX U-boat in 1910

How much of a fully equipped Type IX U-boat could Imperial German shipyards reverse-engineer if one appeared in 1910?

Only gradually: motors, diesels, welding, and limited documentation create major barriers, while British spies would probably expose the project.

A Type IX would confront the 1910 shipyards with electric motors, diesel engines and welding techniques that would be difficult to reproduce. They would have only one submarine and limited documentation to study. The effort is therefore expected to be slow and uncertain, without assuming that every system could be copied successfully. Secrecy presents another problem because British intelligence had extensively penetrated German dockyards. That penetration is also used to explain why German suspicions could focus on human spies while discounting the possibility that Britain was intercepting radio traffic.