No, not self powered, I can't say that I have ever seen anything like that on the tower. Maybe I am using the wrong terminology.
Most head units do not have the power to drive tower speakers properly. They are usually fine for a pair of 6.5" speakers that come from the factory, but not much more. An amp is always recommended.
If you have a tip down tower, you will want to run the wires down to the pivot point. You may want to use a waterproof connector when they reach the hull so that you can remove the tower. If you don't ever do that, then you can run it straight into the hull. A hole can be drilled near the point where the tower is attached to the hull.
Then fish the wire through the inside of the hull to the backside of your stereo. You need to see what you have for outputs that are open though. You either need speakers outputs with adequate power, or pre-amp outputs to go to an amp.
There are plenty of write ups on here for stereo projects. Otherwise, call the local sterero shop and get some help. I know my own limitations when it comes to this stuff. For the same reason I don't go under the hood of my truck.
Good luck,