I agree w/ the ground issue. It is RARE to get engine noise from a boat. REAL rare.
The only other thing it "could" be is: crappy electronics or maybe cheapo RCA connectors.
Does the "feedback" increase as the volume is turned up? If so, it is coming from the radio. If not, then the noise is being introduced thru the amps.

BTW: in this case, disregard my signature. I own a Audio / Video store. Used to do mobile electonics for 15+ years.

No, but if the noise is coming from the power cables, a cap "may" possibly filter the noise out.

A capacitor stores voltage and gets used at peak demands such as a bass note. This levels the demand for power from the alternator/battery.

About 1 Fahrad for every 1000 watts if my memory serves me right and capacitors (much smaller of course) are also 1/2 of a crossover network. They block lows, so if there is a low freq hum or ground loop originating before the cap in signal/voltage flow, it should filter it out.

THATS NOT WHAT I WAS TRYING TO SAY. BUT IT WILL HELP WITH BATT VOLTAGE WHEN THE AMP HAS A LARGE DRAW IT WILL COME FROM THE CAP AND NOT THE BATT.

I might suggest to the stereo company that you are looking to strategically align with several vendors to encapulate all of your clients possible boating needs. I might further suggest to them your committment to your client and share your concern regarding the difficulty you're experiencing resolving this problem. As you are dealing mostly with high-net-worth individuals, you'd presume this stereo company would be very interested in becoming the referral company for each of your clients stereo needs.

See if that gets them to move... if not - move on to one that does.

Custom Car Stereo here in Houston does all of the professional athletes and high-net-worth folks cars, trucks, buses, boats etc.... Maybe they will have a referral for you if those guys don't work out.

Steve (scarabfan) is the owner.

Joe

P.S. Steve, send me my referral check, please!

no

Thanks for the help. The installer has admitted it is not a battery problem and he agreed to handle it for the customer. Once again,the power of OSO comes thru.

Hey Robert,
My battery is dead, could that be caused by my radio?

No,one of your puppies chewed thru the battery cable