There are 3 things you can do to reduce airborne noise in the original 3 versions of Mainship.
Insulate the engine room overhead with insulation. Because its framed with 2 x 4's you can use 2" thick material, 1lb barrier is good, 2lb is better but will make the hatches heavier, although not too heavy because they are each relatively small.
Install an acoustic carpet underlayment in the salon. This works great and feels great. the problem with these boats, all 3 versions, is its impossible to get a good seal on the hatches. What I did was install the acoustic underlayment wall to wall and cut out and attached to all the hatches. I then took the same carpeting and had a "runner" bound by a carpet place to roll out over the hatches from door to the steps down and going several inches past the hatches on the sides. I cut an additional piece of underlayment and put that down under the runner to act as a seal around the hatches. I know this works because there is a outline of the hatches discolored in the foam underlayment like a checkerboard from the vapor leaks from the engine room. This looks, feels and works great. The runner matching the carpet and being bound look very finished and it's easy to roll up to access the engine space.
The last thing is the vent hoses port and starboard. The thin vinyl is nada to noise, and by boxing in the vents and hoses and insulating you seal the last "leak" in the salon.
One additional thing is to try and seal the wire/hose penetration to the steering console. Stuffing foam around the cables or wrapping with a thin insulation like mass loaded vinyl will reduce some of the noise sneaking in around the wire and cable bundle.
Any of these or any in combination will work, with noise more is better