I got into a gunfight with an S-boat once near Brest & it took me a hell of long time to sink it. I ran through over 100 rounds of my 8.8cm ammunition as I was trying to stay at a relatively "safe" distance; out of easy range of her guns. I wasn't about waste a torpedo on such a puny target & I just couldn't hit her guns. The S-boat finally did succumb after about 20-25 minutes (real time). Whenever I encounter them now I avoid engaging them as the risk outweighs any possible reward. They're like MTB's in that you want to swat them but could wind up getting badly stung in the process.