Echo 4bus's comments on "marine" audio being costly and unnecessary on most boats that are well cared for.
I let the "skip marine" advice slide since OP is in Ft Lauderdale and exposed to warm, salt air.
The original proposal of a FA sub would expose the coils to salt air so I lumped the entire recomendation together.

The switch to a sealed box changes things. A sealed box will allow none/minimal air to reach the coils thus, go with standard sub drivers and open up speaker options. For those super paranoid, think of this; do car, truck, convertables that reside near the ocean use marine equipment? --no

The cut out diameter of a 12" W3 is very close to the current hole; Eclipse 10 13/16" vs JL 11.06.
Box size is very close between the JL marine 10 and standard 12. JL M10 recomended box 1cu vs W3 12 at 1.125cu
W3 has twice the power handling and will have significantly less heat buildup without the extra marine coating on the coils.
The moving surface area alone is reason to go 12"

I think you will be much happier with the choice of sealed box vs FA.

Man if you had 12" in boxes I would stay with that. NO WAY JL 10" free airs will do what you had.

Placement of speakers will make a big differnce in sound. If you are going to have, the close to each other make them very close. Like right next to each other, or spread them out. You don't want to have them 6 - 8" apart spread across the gunwals. This will actually hurt the sound and cause what is called comb filtering. It will actually crate dead spots in the cockpit. So if you are going to do 4 sets, do 2 infront of the bolsters close to each other less than 2" and do 2 sets behind the bolsters the same way.

For amplifier you want to have extra power in the amp. If the speakers are rated for 100 watts you want to have 125 to 150 watts or more in the amp. For subs it's not a bad idea to have 2x the rated RMS power of the driver. This will make a huge differnece in output and quality of sound. It will allow the amp to run much cooler and last longer.

Personally there are lots of brands that will give you more bang for the buck than JL. Alpine makes nice stuff for the money. So does Rockford. I have some 6.5" componets that most people would call low end, and they certainly cost far less than JL. I also have the lowest priced 12" subs that RF makes. But you listen to my boat with 2 set's of 6.5" componets and 3 12" sub and you would swear I had a ton more gear that I paid alot more money for. It hit's 115db with ease, is clear as a bell and will make ripples in the water. Setup and the right power makes a big differnce.

ChargeIt I've read all the marinized vs non-marinized audio component threads and opinions and all I can say is that from my experience with re-doing this boat now I will opt for the marinized components. Granted the boat is 17 years old so will non-marinized components hold up for as long as I will most likely own the boat? Probably, but for me it's piece of mind. I'm even going to replace the speaker wire with tinned wire to avoid any chance of corrosion. Some will say overkill and not necessary but I say piece of mind...and advantage to whoever buys this boat after me :lolhit:

I'm pretty much set on JL M10W5's now. The 12's that were in there were basically at the edge of the "meat" of the rear seat and the boxes were really eating into the storage space, so I think the 10's will actually fit a little better and I'm sure they will sound just fine. I'm planning to run a 750/1 to the subs, so if I got this right that would be 375w to each sub, which are rated at 250 peak...should be just right.

Should be a good power ratio for the 10". How big of a box were the 12" in. I have 3 12" in 1.25 cu.ft boxes and still have room for 10 life jackets in the bench.

Nightlife would you recommend then only going with 3 pair? A component up front where the current 6.5's are, a 7.7 coax under the seat (already a hole in the side) and then a 7.7 coax or component? above where the rear 6.5 is? Or what about a 7.7 coax behind the bolster and the another 7.7 diagonally above and rear of it? I can't fit two 7.7's in front of the bolster and I need to keep one down below because there's already a hole there...so really my only options are behind the bolsters.

I don't know exactly, only have two dimensions of the box, but based on the required c.f I think it was probably 12.25x14.75x20 for approx 2 c.f

I can put the M10W5 in a 12x12x12 box for the optimal 1 c.f and have a little bit more storage space than before. The problem is that I keep the anchor under the bench so that's why space is important to me.

the box i am building for my 12's basically take up the entire storage of the bench. i think the dimensions of the box were around 68*17*9.5 (L*W*H). Probably should have gone w/ 10's.

Can you make a drawing of what you are saying I am having a hard time picturing it. But I would not put anything under the seat, just a waste of a speaker. Make a panle to cover the holes or put access cover over them like you see used for your gas tank.

Don't know what the JL 12" require, but my 12" only needed 1.25 cu.ft. I am sure there are 12" low Q subs that will work nicely in a 1 cu.ft box.

Here is a link to the build of my system. As you can see I still have a ton of room in my back seat. I could put my anchors in there and I have flukes. I have anchor lockers in the floor of the cockpit where my batteries are so I keep my anchors there. But I can get a crap load of life vests in there, and good ones not those cheap oranage square ones. I could probably get 4 box anchors in there if that was what I used.
http://s1087.photobucket.com/albums/...Boat%20Stereo/

Thats 6.35 cu.ft. How many 12" subs are you putting in? My 18" dj subs are only in 6.5cu.ft boxes :cartman: