Your current halyard shackle may be working just fine when your halyard needs to be retired. Reusing your current shackle will save on the cost of replacing your halyard.
While this shackle may look rather old and worn, the owner of this yacht trusted it and wanted to reuse it on his new halyard.
The most important thing to remember when splicing your shackle to the new halyard is to remember to slide the shackle onto the line before you make the eye splice in the halyard!
In this example, we are going to use 10mm VPC from New England Ropes. The first step is to pull the core out of the cover. Be sure to insert a needle through the rope just next to the area where you pulled the core out to avoid the line from scooting around.
At this point, the simple straight forward-ness of a Double Braid Class II eye splice ends.
The cover is fed into the core and then tapered gradually to reduce any hard steps that could result in stress points on the halyard when under load. At this point, the core and cover trade places and the cover is fed into the core and the core becomes the cover.
With the cover inside the core and tapered gradually, it is time to complete the splice. Further down the line, you want to pull the core out of the line. You want to pull out plenty of core to allow easier work while splicing. Also, be sure the slide the shackle onto the tail, all the way up to the loop that you pulled out.
The splice will be as big as the span between the cover entering the core and the beginning of the loop. The use of needles through the line will prevent the line from scrunching up in the area of the eye.
Instead of tape, I simply whipped the end of the core and inserted it into the back of the fid and fed it through the loop.
The eye splice is now formed and all that is left to do is taper the tail and feed the loop back into the cover.
Tapering is performed the same way it would be carried out on single braid dyneema. The only difference in tapering the core and tapering single braid dyneema is the VPC core is much softer in your hands compared to dyneema.
With the bury section tapered, be sure to pull the section all the way through the core, ensuring that the area where the cover enters the core now enters the loop as well. With the tail buried all the way in, pull on the scrunched loop to bury the entire tail completely.
Once the tail is buried into the loop, you need to milk the loop back into the cover. I like to tie the line to a winch or mooring cleat and pull hard on the eye splice and let the cover swallow the core back up. At the very end, you will have triple thickness (Cover, Core, and Core) line entering the cover designed for single thickness. This basically means that you need to pull really hard in forceful snaps to get the last bit of loop to be swallowed up by the cover.
Once the eye splice is complete, you need to whip the splice to lock it in place. You must use a needle and whipping thread driven through the cover and core to lock the splice in place. The whipping does help to make the splice look prettier, but it also serves as a structural lock to hold everything in place.