There is a thread on this site title "Marine stereo needed?" that has a lot of good info. While it's a couple of years old much of the commentary is still applicable. I ended up buying the Kenwood car stereo online from Cruthfield that was recommended by one of the posters and have been very happy with it. Especially pleased with the fact that it has a remote control. My unit is in the cabin so I decided I did not need a marine quality unit. I've had it for 2 years and so far so good.
I put 2 small poly planar speakers in the winch boxes of my cockpit combing and that has also worked out well.