I never used the big wave mod as such, but I started using SH3 Commander a couple of weeks ago (finally got a version that didn't give me CTDs) and it has an easy drop-down box to set wave heights - I have been using 1.25x and experimenting with 1.5x wave heights, and I get a pretty decent feel for storm waves, water sweeping up over the bridge crew and stuff when at 15m/s winds.
Might want to give it a try - it also does some other cool stuff like putting "real" ship names next to your victims in your logs, making it easy to adjust the deck gun reload speed, generating a very cool personnel file for your kaleun, letting you experiment with different fatigue models, do some extra crew management stuff, etc. Very cool little program - kudos to the modders
