Pete McCrary Posted April 2, 2019 Report Share Posted April 2, 2019 The original trailer for Chessie (a Core Sound 20 Mk 3) carried her (1" yellow pine keel w/SS half-oval) on three hard-rubber rollers. The side bunks were adjusted to carry loads just enough to keep her balanced at the verticle. That arrangement concentrated her load on just three places and, over many miles at highway speeds, the stresses caused by potholes, RR Xings, unseen speed "humps," etc., -- caused the rollers to be severely damaged at their centers (the only load-bearing part). Note that there has been no noticeable damage to the keel. The chipped-away rubber pieces made the roller no longer cylindrical to the point that they often didn't "roll" at all -- causing launching and retrieval problems. I learned that Graham had similar problems and was considering a trough with many rollers. That reminded me that I had used flat platforms to carry my CLC PocketShip and a Com-Pac Eclipse (both had, respectively, wide ~2" & ~4" flat keels). So, maybe the concept would work for a CS20.3 and other boats without flat keels. So, here's what I came up with. This shows the rip-cuts made on a 16' X 2 X 8 straight piece from Home Depot. The bottom of the board was covered with two epoxy saturated and overlapping (only by an inch at the center) 4 inch X 10 ounce FG tapes over the entire length. The top and sides were covered with three coats of neat epoxy -- and the top with a final coat of neat epoxy mixed with powered graphite. For Chessie's trailer I trimmed the 16' trough down to just 14 feet. The "rough cut" cross section. The sharp edge of the half-round centerline trough was rounded over with a smooth plane. The 4 coats of neat epoxy tended to collect (at bit) at the bottom of the half round -- which was desired, as it would carry the concentration of stress and sliding fiction. BTW, the half round SS screws (thru the keel's SS half oval) were "smoothed" over. I measured the height of each roller (above) their wooden mounts and planned to mount the trough such that it's bottom would duplicate the position of the [three] rollers being replaced. Alan provided me with offsets (from the waterline) of the keel at the three points where the rollers were mounted on the trailer. From this I determined that the mid support (under the trough) should be ~ 1 and 15/32" lower than a straight line from the forward mount to the aft mount. Trough lined up on the trailer centerline. Forward support with spacers. Notice X-beam doubler (new wood) under. View from port side slightly aft. Middle support. Trough is not loaded. Now the trough is artificially loaded with clamps. When the boat was lowered onto the trough, there was ~1/2" space -- into which was placed a spacer. Aft support. Shallow-V guides to help guide the keel into the trough. Note that the CB catcher is raised so that the CB won't hang up on the X-beam. The centerline of the trough was further lubricated with paste floor wax. Next I'll report the proof-of-concept trial launch and recovery. Quote Link to comment Share on other sites More sharing options...
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