The starter slave solenoid can cause similar issues. Sometimes loose connections and sometimes a bad slave solenoid. It is a cheap part by boat standards. There are threads on the subject in the forum.
I followed a lot of the guidance in this thread from hack4alivin although I used JL Audio speakers and amplifier. http://clubsearay.com/showthread.php/38861-06-DA320-Stereo-Upgrade-project/page3?highlight=stereo
If the manual isn't clear I wouldn't connect anything until I talked to MTX or Crutchfield technical support. You have a 600W mono-block Class D amplifier and the connection that you are describing isn't going to be enough. My 500W, 3-channel Class D amplifier from JL Audio specified a minimum...
This video is actually a composite of two different cruise ships in different storms. The exterior shots from the helicopter are the cruise ship Voyager off of Majorca. A wave had taken out the windows of the bridge and power to all four engines was lost. As Shaun said, this is a small cruise...
The Irish Independent is reporting that it is believed that the ship sank. http://www.independent.ie/irish-news/1million-ratinfested-ship-has-sunk-irish-coast-guard-claims-29947286.html
The fantastic pricing on the 740s is to clear inventory for the new model. Be sure to get Jim to advise you on your proposed timing as the inventory might be running out. The 740s is an awesome unit, especially at the current discount.
http://clubsearay.com/showthread.php/62969-Occasional-no-start-click-click?p=708371&highlight=#post708371
Check out this thread and see if the issue sounds similar.