There is an eye strap on the front of the mast. The 3 raps of blue line go through it and through the triple block's becket. That is Dynema rope that is used to minimize stretch. It does a good job of holding the triple block low to the cuddy roof. However, this really only works well if you are not cleating off halyards on the cuddy roof. Otherwise if you do the halyards cross with the vang to make an X shape which causes the vang to receive resistance on broad/beam reaches. And that is no good. I added the pivot cleats for the halyards to eliminate the cross up between the two.
Edit... It is actually a quadruple wrap. 1 wrap goes through the triple block, and another goes through the cascade rope (spliced loop) from the big block at the boom, and then 2 more around the mast itself to give the leverage to winch the whole thing in and tie a good knot to keep it close to the mast/cuddy roof. It detaches at the boom, and I just sling it down into the cuddy when on the trailer. I never actually remove it from the mast.