How can i make a Water Script?

I want to make a water script that makes your torso float on a brick that haves the canCollide property off so i tried whit the function OnTouch(hit) but idk what to use Vector3 or BodyPosition? I want to make that people can float on that brick and move on every way please help me :D?

If I'm ever doing this sort of thing, I generally add a BodyPosition object to the character and in an infinite loop set the position of it to the torso's X and Z position and the water's Y position. You can then make it more advanced by gradually moving the Y position up and down to make a bob effect. Make sure your BodyPosition object is given enough power to actually keep the player in the right position.