This thread is a good start:
http://www.subsim.com/radioroom/showthread.php?t=111716
and yes, re: normal surface speed.
Try this (tested on Tambor class): [you will need CapnCox's tweak files]
NSS-Tambor_sim.txt
NSS-Tambor_sim.txt
[NSS-Tambor_sim.txt]
Set Propulsion Diesel:
Max Speed: 55
Eng_power= 16500
eng_rpm = 25000
knotsSufaced = 50
That should be enough to get a barefoot skiier-up!
have fun