Holder20 hull question.

This is how I fit my bunks.

New best quality 2x4's: With a circular saw, four long kerfs were made (but not through the ends.)


The weight of the boat compresses the kerfs (now like leaf springs) and the shape of the bunk equals the complex shape of the hull.


Jack the boat back up, add glue to the kerfs, and drop the hull back into position (clean up squeeze out.) When the glue dries, the bunks are nicely fitted (after this picture was taken I used much more glue.)

 

Bunks

That is a nice job on the bunks, I hadn't seen that trick.
Of course, they still have to be under the strong points of the hull, and many hulls don't have any areas that are safe to load with the weight of the boat. Fore and aft bunks, no matter how well fitted, often have the verticals under the wrong places, resulting in eventual hull damage. Many of the current one-design classes have custom trailers designed with molded supports that go across the boat where a bulkhead takes the compression. Melges 24s and 32s have nice examples, as well as many of the customized A-cat and Nacra multis.
The gunnel or strap supports seen on Laser trailers also are good on light boats.
B

 

This boat has no bulkheads in the bunk areas (although it is cored.) All the weight rides on those bunks and three large keel rollers.

 

Even a single partial bulkhead per side would be adequate if positioned about halfway along the bunks. Grind down past gelcoat (if present), scribe an on-edge (24" long?) 2 x 4 to the shape and belt-sand the edge opposite the hull to look nice, rounding top and bottom in and creating a glassable surface. With "dents" pushed out as well as you can to normal, set the wood in an epoxy mush, cove, and later glass in with maybe eight layers of 10 oz cloth/epoxy.
This is based on the idea that since no frame or bulkhead exists along the entire bunk, moving the bunks probably won't be possible.

 

I was talking about my C15. It doesn't have bulkheads under the bunks, but it does have coring and stringers. It also rides on three of these keel rollers. The Holder definitely needs bulkheads.