I think that you are referring to the 1974 Kriegsspiel at the Staff College ,Camberley,of which the results were:But here is the kicker in all this the Sandhurst experiment says that significant numbers of German troops would have got ashore and operated for at least 6-8 weeks before supply became the issue that caused collapse.
So they clearly believed that German had the ability to get troops ashore in significant numbers.
It is an interesting point and to be honest I had not really looked at the barges in any great depth as it was general knowledge that they were unsuitable for the task.