Stereo Post Upgrade assistance needed

[Paxdad]

I just had a few stereo components upgraded/ replaced in my boat and there is quite a bit of engine noise coming through the speakers with the motor running. I have inquired back with the company that did the upgrades and install but wanted to get a few opinions of what might cause this situation.
The upgrades included the following:
Arc Audio XDi805 amp (in boat and sub)
Arc Audio 600.2 amp (tower running WS Pro485s)
Rockford Fosgate M262B (in boat speakers)
AGM Battery

The entire system was rewired using the existing CMD 5 head unit, WS420 equalizer, and WS 10 open air sub.
To say the least I am a bit concerned that given the money spent the outcome is certainly not what I expected it to be.

[aZ`]

Noise entering the audio system is caused in the majority of cases by one or more ground loops. Check and make sure that every piece of equipment has a quality earth and in only one place. Ie, the head unit earth wire should go directly into the loom which leads to the battery, not to the bolt on the back and then into the loom. This example creates a ground loop as head unit is grounded from it's intended wire as well as through the metal body of the unit. Adding additional earthing wires IS NOT the way to increase load capacity of the wiring. Do not use the bolt on the back of the head unit as an earth terminal, It's there for mounting purposes!

Read through this http://www.termpro.com/asp/pubs.asp?ID=121 in particular the 10 commandments.

It will more than likely be wiring, and also likely be a simple fix, the hard part will be finding the error.