Super-silent cruise speeds end at 8-10 knots tops even for the best of boats - go higher, and you have cavitation and all the not-nice stuff kick in. The larger the boat, the worse it's hydro-symmetry and balance, and ultimately the noisier it will be with speed. Shep's boat has more shafts and larger shaft hatches than other boats? Cavitation elements. Everything on the hull is a cavitation noise factor when you go higher.
Read some stuff here, sub hunters:
http://www.fas.org/spp/eprint/snf03221.htm
http://www.fas.org/spp/eprint/snf03221.htm
P.S. Seriously, the US doesn't have Anti-Torpedo systems like RBU-6000/12000 on carriers and other order ships?
I admit I'm not knowledgeable of US antitorpedo technologies. ... And if they have such salvo mechanisms.


