How French shipyard workers sabotaged German construction

What was a memorable case of sabotage during wartime ship construction?

French workers connected piping so bilge water contaminated the fuel, crippling the ship until the concealed fault was finally traced.

An example of French sabotage involves connecting pipework so that bilge water mixed with fuel. Both systems became contaminated and the affected ship was barely able to move. The concealed connection took months to identify. This illustrates how construction work could leave a vessel outwardly intact while making its machinery persistently unreliable. The vessel and workers are not named in the account.