Is the Power Acoustik OD1-5000D worth it?

It can be a good value if you are on a tight budget and need a lot of power for a subwoofer. However, be aware that it may not deliver its full rated power and may overheat under heavy use.

Does it really produce 5000 watts?

The 5000-watt rating is peak power. In real-world use, it likely produces less continuous power, and some users report it does not meet the claimed output.

Can I use this amplifier in a boat?

No, it is not suitable for boats. It is designed for car use only and is not marine-grade.

What subwoofers work best with this amp?

It works well with subwoofers that can handle high power, typically dual voice coil subs wired to a low impedance load. Check the amp's stable impedance rating before connecting.