Re: keel rollers
If you use them it takes too little time to launch and load. Because they are poly, they are hard as a rock, don't deform and last forever. I load my boat in just a few minutes, it goes straight up the trailer perfect the first time, every time.
Buttttt, they are quite costly. Most people would rather pay 1/4 the price and replace them every few years. Also, my observations at the launch ramp would indicate that most people like to back in so far that they have to get their feet wet, bubble exhaust from their tailpipe in the water, then launch and reload several times to get the boat half way straight.