I don't even do the full waterline. I just do what's know as the football shape that is the direct bottom of the boat.It just gives extra protection for going over a submerged rock and I have done a lot of those. I have never gone through the glass but have put a good white line in it. We all want light weight but I often paddle in some rough conditions (not excessive) afnd that water is often not clear. My boats seem to average high 40's to 54 or so. VCP hatch instillations add weight too. I made a S&G rolling boat years back and that was about 30. Yes putting kayaks on the car is never fun and it doesn't get easier.