Spectra lashing instead of moused shackle?

[whimsy]

Thinking about it and looking for answers, perhaps a soft shackle would be just the thing to use.

Any other recommendations?

[Stumble]

I am not sure what you are trying to describe. If it is just a normal mast head crane, there is no need to run the shackle through the mast. Just run a chase line, then pull the tail of the halyard. If not, can you post some pictures or a drawing? I am having a hard time visualizing what you are trying to do.

[teknocholer]

I did something similar with the topping lift on my Nonsuch 26. The padeye at the end of the wishbone (boom) is on the outside of the end casting, so that the shackle was levered sideways against the casting. To get a better lead, I used a Dyneema link.

I made a loop of 3mm (1/8") Dyneema, about 36'' in circumference, joining the ends with an end-to-end splice. This was doubled and put through the padeye, then the end loops were brought together and attached to the shackle. This gave 8 parallel turns of cord with a breaking strength of 2200 lb/turn. I wrapped the whole bundle in rigging tape to reduce chafe.

This method means you would have to use shackles to attach the lines to the Dyneema link, but you have the shackles already, and it's neater than knots, with no chance of working loose.

The setup is in place for about 5 months of the year, then disassembled and inspected before being put away for the winter. The cord is going into its fourth season with minimal chafe, but I don't know if a lifespan of a decade is realistic. I certainly recommend regular inspections, although that's harder in your case than mine. At any event, the cost and effort of making a replacement are minor.

[Brion Toss]

Hello,
First, the standard safety factor in recreational sailing gear is a mere 2:1. It is absurdly easy to exceed the strength of steel shackles, either with lashings or soft shackles. Cheaper, too, as a rule. The only downside, if you can call it that, is that lashings and soft shackles are skill-intensive; you have to know how to distribute the load among turns of a lashing, and how to start and finish securely, for instance.
Fair leads,
Brion Toss