I need to be able to get my centerboard dinghy on and off a beach--maybe a rough beach. I once saw some Italian made beach rollers that looked pretty tough. I can't find a source for them now. The dinghy, laden, will be in the neighborhood of 600 pounds. The rollers would be used in conjunction with a block and tackle. Any ideas? The thing about rollers is that they are longer than bumpers and so are not so hard to keep under the boat.