Hello!
It's a hard project if you want simultaneously realistic, good quality, and musical intro.
I can make it in 2 -3 days. I'll combine sampled sounds from real ship horns with wind instrument(with changed formants). Also to have good loop I'll make 2 files: one for looping and other to be played in cue which later modulates smooth mixing with song intro.
I will do it in pro tools, reason, maybe melodyne.
Thanks.
Oleg