Underwater Effect Script Removes Skybox and gives no effect

Hey guys
So i am working on my game and one of my levels includes wated. (its basically a island ). But i have played the island demo and there is a underwater effect in that demo. i have searched for a script and i found one on the unifycommunity. The script said to attach it to the main camera so i did. when i went into play mode, there was no effect underwater at all and my skybox had disappeared completely. It was saying stuff about water planes and stuff so i didnt know if that had something to do with it. plz if anyone can help i will be so happy as it is a big feature in my game. any video tutorial links would be appreciated aswell. If you require the script here it is:
//This script enables underwater effects. Attach to main camera.

//Define variables
var underwaterLevel = 7;

//The scene’s default fog settings
private var defaultFog = RenderSettings.fog;
private var defaultFogColor = RenderSettings.fogColor;
private var defaultFogDensity = RenderSettings.fogDensity;
private var defaultSkybox = RenderSettings.skybox;
var noSkybox : Material;

function Start () {
//Set the background color
camera.backgroundColor = Color (0, 0.4, 0.7, 1);
}

function Update () {
if (transform.position.y < underwaterLevel) {
RenderSettings.fog = true;
RenderSettings.fogColor = Color (0, 0.4, 0.7, 0.6);
RenderSettings.fogDensity = 0.04;
RenderSettings.skybox = noSkybox;
}

else {
	RenderSettings.fog = defaultFog;
	RenderSettings.fogColor = defaultFogColor;
	RenderSettings.fogDensity = defaultFogDensity;
	RenderSettings.skybox = defaultSkybox;
}

}

Visit Unity3d Underwater Effect · GitHub

it contains a far better script