After reading the rules I believe adding a plate to the forward portion of the traveler to attached the main sheet block and swivel cleat is allowed - "5.4.1.9 Fixed-position or swivel base mainsheet cleat(s) may be attached to or in close proximity to the traveler."

However I also read the the following is prohibited. What is a mainsheet bridle system? - ".5.4.2.3 Relocating or changing the length of the mainsheet traveler or the use of an alternative mainsheet bridle system."

One of the stated intentions is not to allow a strop instead of the bail that would effectively reduce the amount of mainsheet. The bail is the bridle system with the U-Bolt on the boom and where the mainsheet attaches to the boom. What you describe for attaching to the traveller is the intention of what the rules allow. I'm sure the class measurer will speak up if there is anything wrong with it.

I recall this same discussion on the forum several years back.

Edit: Found this old link on Mainsheet Strop

Correct, J30 Rule 5.9.1.9 Allow the attachment of the main sheet block to the front or back of the traveler. Rule 5.9.2.2 Prohibits the use of a main sheet pennant. This is a short piece of line or wire between the top block of the main sheet and the bail on the boom and shortening the main sheet.

There is no provision to allow the replacement of the bail on the boom with a strap or bridle as is often done on carbon fiber booms.

Larry Christy
Class Measurerer

Larry - Thanks for the confirmation.

Doug - you may want to read this post on issues found when I inspected the boom bail on Rhapsody. Bob Rutsch found the same problem on Bebop and wrote about it in this post - Boom Repair & Boom Bail. The fix is pretty easy but better to do it early rather than having to deal with it when it's blowing like stink.