Tower speaker question

Looking to add a pair of tower speakers to our boat. Nothing special, really. We're not looking to use them for wakeboarding at all. Possibly surfing from time to time, but mainly, for when we're tied up floating around, so we can hear the music or the game, outside of the boat. Would also like to be able to turn them off on command.

As always, want to try and do it on the cheap, just looking for the best way to do it.
Right now I'm looking at a pair of Polk DB651's, not sure if i need to run an amp to them or just run them directly from the head unit on a switch to turn them on and off.

Thoughts?

Kicker KMT6. Look on ebay, you can get them just over 200$ . Really you can't go wrong with that.

You just need a good amp, and covers to protect them from the sun.

I think I remember people saying DB651's are good in boat speakers but not so great as tower speakers. for your needs I would think a good set of car audio speakers(marine rated) would be good with a small(100x2) amp or so. I would find out which ones have the best midbass response so you don't get too high/bright of a sound.

Exile and Wetsounds both make regular coaxial tower speakers but I am not sure they are super cheap.

I had the polk db651's on my tower. I think I got 4 with the cans on ebay for about 300 bucks. I think they will work fine for what you want. you will need an amp for them though, but nothing too crazy. I think if you matched the rms rating per speaker to what a 4 channel amp can put out, you should be fine. but I really don't know crap about stereo stuff. I had 4 db651, and a rockford 300.4 amp, and they sounded just fine for surfing, and while playing around the boat. I upgraded, because I wanted to hear music while wakeboarding, which you wont hear with polks............