Hi, I use a crusifix type trailer carrying a 15'6 boat, weight approx 600lbs all up, the existing keel rollers are traditional rubber,the boat settles on these creating a flat spot and needs an initial bit of oomph to start getting it off. I am considering fitting nylon rollers to overcome this, but before going down this route, has anyone experience why this maybe not a good idea? ie, poss damage to wooden keel etc: Regards, Al.