http://www.uboataces.com/articles-rocket-uboat.shtml
This link seems to reinforce the opinion, that Luftwaffe v Kriegsmarine inter-service rivalry meant some resistance to deploying a "Luftwaffe weapon" - the V-1 - onto Kriegsmarine U-Boats.
Equally interesting are the US plans to potentially use the sub-launched V-1/Loons against Japanese targets during the invasion of the Japanese home islands.
...geoff