Originally Posted by Retoxtony
Can't remember my measurements but i believe much more than 6" into the foot area and it would start to be in the way. Also not alot of height either. I figured a 10" would be as big as i would probably go.
Would it be possible to use a free air sub and put it in the walkway somewhere?
Here are a few basic acoustic considerations.
An IB (free air) sub can do a good job, but it requires a rigid baffle, an infinite enclosure (2.25 cu.ft.+) for a 10", plus total front to rear isolation for a distance of at least a quarter wavelength of the lowest frequency you need to reproduce. You may be able to accomplish all that. When placing a sub in the cockpit, the surrounding boundaries (sole, coaming, etc.) provide reinforcing planes. Once out of the bathtub, so to speak, bass energy tends to flash evaporate, unlike an enclosed vehicle cabin. By placing a sub in the pass-through, it has been removed from the perimeter of the cockpit with its contrbution divided. Helpful to the bow occupants. A marked reduction in the cockpit.
Placing a sub in a locker or compartment can create a significant reduction in output. At minimum the woofer will have to move four times as far and the amplifier will have to produce four times the power to compete with a direct radiating woofer. Both (excursion & power) are very limited resources. The woofer that operates most conservatively always sounds the best. In any case, any degree of pitch accuracy, transients and attack, have been filtered out. You are left with a rumbling boat shaker but not much of a bass music maker. You can turn the boat into swiss cheese to vent the compartment for some improvement.
Direct-radiating from under the dash. A contemporary 10-inch 'air suspension' woofer needs one cubic feet of EXTERNAL enclosure to provide the required internal net displacement. Any simple enclosure shape that will satisfy that 1728 cu.in. volume is good. 7"X12"X21" with 0.75" construction for example. I would prefer a 10" direct radiating subwoofer over a choked 12" subwoofer in a compartment.
Ultimately we make compromises as we take the best that each individual boat offers. You want to take the leper with the most fingers.