Many boats-particularly express fishers, where the helm is often located literally on top of the engine room-produce 90 dB-A or more while cruising. According to OSHA, exposure to this much noise for eight hours or more per day requires ear protection. On top of that, cruising on a loud boat is simply miserable. Luckily, $500 will get you 250 square feet of 1"-thick 3M Thinsulate marine insulation. That's enough to soundproof an engine room or engine box on most boats less than 40'. However, have this stuff installed by the marine yard and you'll blow the budget. Fortunately, Thinsulate can be easily cut and stapled onto wooden bulkheads or stringers or, if you're affixing it to fiberglass, glued with 3M adhesive. It's an easy job any boat owner can handle, which you'll be happy you did every time you crank the engines and hear them whisper instead of roar.