I thought I had seen a thread about this a while back but couldn't find it. I just experimented with this mod last night, as I was able to find a lone small freighter during some calm weather and wanted to save my torps for bigger game.
The slight delay between the impact/explosion of my shells and the sound of the explosion worked very well - Kudos to the modder
This mod seems to work/be compatible with RUB1.44, at least based on my brief testing so far. If you're interested, you can find this one over here (in the SH3 downloads section - it's called "Avg. Joe's Torpedo and Deck Gun Speed of Sound..."):
http://u-boot.realsimulation.com/
Good luck and good hunting!