Acute hearing sensitivity called recruitment or hyperacusis often accompanies tinnitus. I have that as well. I also have hearing loss which tends to make tinnitus louder since the less noise you hear, the more tinnitus you hear. One thing that helps me with noise flying for instance is to use the Bose noise cancellation headphones. I am very particular about comfort and I can wear these and sleep comfortably on my back. I add nature sounds and plug them to my Walkman on the night table. The only thing was getting used to sleeping on my back and that took a week or so. I put a pillow under my knees as recommended by my physiotherapist. The noise cancellation headphones, if you used them, would protect your ears from noises on the boat.