Installing pods

I'm making some ply/fiberglass pods to put on my boat, and I'm suck on how to install them. I've heard somewhere they should be about 1/2" above the bottom of your hull when installed. But what I'm not sure about is the angle. If I put a straight edge along the bottom of my boat, should the back of the pods be the same height above the straight edge as it is at the front of the pods, or should there be a little bigger gap at the back?