Hi Guys I am Val. What are your thoughts or concerns about this approach of attaching the Jackline for the Main sail to an Ungrooved Round Mast.
I am testing it in a 1/2" diameter 0.049 wall thick aluminum tube, but I think the same approach can be used also in a 0.035 tube filled with balsa wood if the wall is too thin.
I am using 2-56 Brass Threaded Rigging Couplers that with a 2-56 Die I threaded up to the first hole. I drilled holes in the mast every 4" and threaded with the 2-56 Tap. The hole doesn't go through so when you screw the coupler in place it will stop when you touch the opposite wall of the tube. What you have to do next is to cut the couplers to the right lent. You have in this way total control of the gap between the Jackline and the mast.
What also this method for attaching Shrouds, Forestay and Jumper Strut Wire.....

Val,
Before you proceed, it appears you have not visited the Class Building Site at www.ec12.info. Go to building an EC12 and you will see links down the left side of the page to many subjects. Those links lead to other more details subjects.

The site is involved with the basics of building a boat and covers several options through the Electronic Checklist. Rigging is a big section and you will find answers to all your questions.

Ungrooved mast and external jacklines are a lot of work and were used in the 1970's. Today internal sail hanks are used in grooves with or without a jackline.

...94

As I am UNrigging a rig done on a round mast I FIRMLY 2nd that emotion.Grooved masts are readily available from sources on the suppliers page and I can highly recommend you go with a grooved mast with slugs as a much better way to bend on your main.

R.C.Greer