Here are three videos illustrating the butterfly assembly method which B&B Yacht Designs use. Thought some forum members might enjoy watching them.
The design being assembled is the Core Sound 15
http://www.bandbyachtdesigns.com/cs15.htmAnd the first video
https://m.youtube.com/watch?v=bPjfXCXAxwE&list=PLCCJRycps-_mbO-Lfdr0s8OZX-4QOZCzLAs each video comes to an end there is a link to the next one.
Brian