Dynamat in speaker cans

I just finished putting Dynamat inside my speaker cans. I'm hoping that it will help the sound further back and lessen the sound inside the boat. I have HLCDs but think that they are too loud for the folks in the boat when the volume is up enough for a rider to hear. I'm hoping this will help. I'll let everyone know if there is a difference.

When I pulled the speaker out, I had a lot of white powder aluminum corrosion inside the can. Is there anything you guys/gals are doing to keep the inside of the can from corroding? Even my crossover circuit board was starting to corrode. I take the speakers out for the winter but leave them up in the summer.

I actually have some left over. Do you think that adding another layer inside the can, just on on bottom would help keep the sound away from those sitting directly under the speakers?

I actually put dynamat in the bottom of my speaker cans and seems to help a bit.

You can always put them on top of the tower.