I had some questions about the actual submerged performance of the Type XI. I understand that their top speed was about 17 knots for 1 hour submerged. Does this mean that after 1 hour the batteries are completely drained or is that practical amount of time they could maintain this speed. Since an hour is not a lot of time how useful would the top speed be and in what kind of situations would they use top speed and for how long? Was it only for dire emergencies? Also, based on my understanding, the maximum speed at which asidic worked for a DE was about 15 knots it doesn\'t seem like it could very easily outrun a DE with at most a 2 knot difference. I\'ve found the posts at this forum very interesting and informative and would greatly appreciate some information on this.