Oh, and also remember that when packing stuff into DAT, the program makes an automatic backup of the original DAT file in the same folder. So if you are like me, working with the DAT that's already in MODS folder in SH3 (for JGSME) - make sure to delete that Backup file because it will confuse JGSME I think.
I've reworked the boat further more, and I think it's starting to be even nicer. Gonna test it next..