Well I build em and yes you can hear them, in fact that's how I sell most of mine. People will hear me at the lake and say I've never heard tower speakers so clear before. The biggest thing that you have to remember is it takes power to make these things loud. If you underpower them you can't overcome the exhaust note of the boat, plus you'll ruin the speakers because of clipping.
I always recommend a high power 2 channel amp and then run my speakers at 2 ohms. Run them off the rear channel output so no "Y"'s are required as with some 4 channel amps and your all set. Check out our website
http://www.tytebox.com for some pictures, most of our boxes go out with 6x9's in them.
Oh and BTW bring ear plugs for anyone sitting aft of the tower. It's loud back there. In fact one of our boxes calc'd out at 123dB at your head and 90+ at 50ft. To put it in perspective, a jackhammer is 125dB, a lawnmower is around 90dB and a busy city street is around 70dB.
And one more thing, we have found in our research that it pretty much takes 4 speakers to make audible sound behind the boat. 2 look good, but 4 does the job.
(Message edited by whitevlx on March 12, 2004)