birch speaker baffle rings

I installed a MB Quart free air marine sub in the rear L of my pontoon boat firing to the side behind the driver seat and it sounds awful (vibrates and is boomy).  Earmark audio uses birch baffle rings on the back of the their subs on boat installs, would this help? I am sending the sub rated at 150 rms 160 watts from a 2 channel clarion marine amp bridged.  I have 2 other 6.5 Mb quart nkd 116's in the rear and 6 in the front benches. All 8 are run off of a 4 x 80 clarion marine amp with 2 maxx bass units for front and rear. Very happy with the sound of the 6.5's but am getting some vibration in the plastic seat bases.  Could the 6.5's also benefit from birch baffles?  I cannot even hear the sub when sitting in the front benches and am looking for possible fixes, thanks in advance

Most of the time you'll see the Birch baffles because the Fiberglass isn't thick enough to support a heavy subwoofer.  Birch is used a lot in marine applications when wood is called for structural support.  The biggest problem most subwoofer applications in boats run into is that in an open environment, sub performance is completely compromised.  Take a 10" home theater subwoofer and listen to it in a gymnasium, compared to your small living room.  Same idea here.  To get the most out of your subwoofer, make sure that the front and the rear of the subwoofer are seperated, which it sounds like it already is.