custom speakers for boat interior

[kford]

I need a pair of speakers for the interior of a 30 foot sailboat. Previously, I have bought "marine" speakers in plastic boxes that mount with a bracket. Have never been happy with the sound, particularly with low frequency. I would expect that decent drivers in a custom MDF box would be better. I want to build a pair of speakers that meet the following criteria:
- can be driven by the amps in the Sony car stereo
- can produce good musical low frequencies at low listening levels (for use when in cabin - very quiet environment and very small space)
- environment is very dry
- enclosure must be small - 300 to 500 cubic inches and NOT rear ported
- component cost < $100
- sound enough better than the "marine" speakers to be worth the trouble

Single driver design is acceptable also. I'm open to any ideas. I just want high quality, low volume bass. Heck, my Creative 2.1 computer speakers deliver much better bass than my "marine" speakers. Any suggestions? Thanks.

[djn]

On my 36' Sparkman and Steves I messed around with DIY and marine speakers and ended up with Alpine car speakers and a Kenwood CD/HD/FM/USB car stereo. All the speakers were in the cabin, not in the cockpit. I also had a pigtail to hook up my laptop to the sound system so I could watch movies on rainy days with surround.