Amlifier Install on Outboard

[Hairygary]

My boat has a 130hp outboard, and I wanted to install a amplifier to upgrade my stereo system, but I am concerned because the alternator on my outboard is 3 amps at idle and tops out a 9 amps. I have a second battery in my boat, but I do not have an isolator on my system and this 2nd battery receives no charge.

I was wondering If i run the amplifier off the second battery, how long would it work before the battery dies. Could I get an 8 hour day out of it and then just charge it at the end of the day. The amplifier I was looking at was a Sony marine XM-604m, whichs it has a drain of 32 Amps at full load on the amp. I will be powering my tower speakers (kicker components) and a subwoofer. I am going to run my stock speakers of the head unit.

Any help would be greatly appeciated as I do not know if I should consider an AMP with an outboard since the alternator is so weak. The batteries I have are blue top Optimas