When working out the supports for C231 pictured earlier in the thread, I did not work from the cradle design, which seemed to restrictive. I started with laying out the possibilities on the trailer.
First thing I did was to shift the axles as far forward as I could, which made sense considering the length of the front part of the trailer. They tend to be too far aft on power poat setups.
Next I assessed the crossbeams that were existing. The forward one on my trailer was fixed (welded in position). The rear one was possible to adjust by shifting it to different mounting holes.
This left a big gap in the center near the axles where most of the weight effectively falls. Luckily I was able to order a copy of the rear "pivot beam" from the original manufacturer, galvanized and all, and it was not to spendy either. I located it as close as I could to the center of gravity of the boat, perhaps aft a bit to get it under the level portion of the keel bottom. Had to add my own mouting bolt holes to the frame, but the bolts I obtained from the manufacturere too, as they are a particular grade of bolt, and they pretty much support the boat.
I then decided to allign the vertical support posts with the crossbeams. Originally I was going to mount them on the longitudinal rails of the trailer so that the cross beams were not doing all the work, but the complexity of angling the cuts and welds inward enough to land the pads below the waterline intimidated me, so I opted for mounting them to the crossbeams and running them straight up vertically.
So that leaves the all-critical question of how high to make them so that they work with the boat. I did the calculations graphically using the lines drawing which I downloaded from one of the other posts on this site. If you can figure out how to work a lines drawing, it is not too hard to "connect the dots" and measure off the drawing to the right spot. Then just deduct for the pads and adjustment. I think I cut off 6" to allow for brownell boat stand pads plus some adjustment.
I will look for the drawing I did to figure this out, which is not elegant, but might help in the understanding.
I cannot remember if I used 2"x2"x1/4" or 2"x2"x3/16" tubing for the verticals, but one of those works well with the stock brownell pads.
I also had to grind off one side of the brownell pad sockets so that it would be able to pivot enough to meet the slope of the hull without binding first.
I found large thick galvanized washers to go between the top of the post and the round portion of the pad adjuster. The pad adjuster are designed to sit on close fitting round tubing of to small a dimension for a trailer support.
If needed I can get a picture of exactly where C231 is sitting (in my backyard) in relation to the axles and the keel, which might be helpfull when the time comes to place the boat.
Honestly, it was a pretty big head scratcher for me for a lot of evenings, and some of it did not come together until I was cutting and welding, but it did work and felt pretty good to figure it out on my own, for the most part.
Oh, and the lines drawing should have the center of gravity indicated on it, not to be confused with the center of lateral area....
Sail trailers in Columbus GA will sell complete uprights ready to install for $85.00 each if you happen to be going to GA over the holidays. They have a website, I don't have the link right now. Mine have about 12 inches of adjustment. Carl
So here is the (almost) finished product. It'll get a coat or two of paint after I launch this Spring. Towed nicely - even in rather poor conditions - and is about 2 feet shorter (in altitude) than my previous trailer. Only measurement that was off was the height of the front posts. I'd like them to be 6 or 8 inches taller. Fix in the spring. I'll add a ladder too on the tongue.
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