I'm currently building a 12mR Columbia, Americas Cup winner from 1958. When producing the plug, I altered the stern slightly, making the hull an additional 4 cm longer compared to the original.
The original boat can still be built, by cutting the stern back to the original negative version.
I'm posting some pictures to show the progress. 13.8kg, 30.4 pounds of lead, 178cm or 70 inches long. Mast hight will be 210cm.
/Lars from Sweden