constant diameter 12 strand end for end splice

[allene]

Has anyone done and tested a constant diameter end for end splice in 12 strand? I did a quick test by removing half the strands and doing the splice in what was basically 6 strand and it looks promising. I am sure a longer taper would make it look better so it wasn't just 12 going to 6 abruptly.

For example, one side could go from 12 to 9 to 6 to 3 then 0. The other side could do the same so that the net was a constant 12 strands. Or you could make the taper in 12 steps again for a constant 12 strand diameter.

This came up because I want to splice 5/16 Amsteel to 5/16 Tenex, both 12 strand single braid. This is for a halyard. The line ended up over 1/2 inch thick in the splice, which might be too large for the new mast with internal halyards, not sure as I have not heard back from the guy building the mast. But in any event, while I wanted the line that will be in the area of the winch to be thicker than 5/16 to make it easier to handle, 1/2 inch seems too thick. I think removing some strands in the area of the splice will give me what I want but I just thought about the logical extension of this to all the way to constant diameter. The halyard has significant excess strength as it is built for stretch and as long as I have full diameter Amsteel on the winch, I should be OK stretch wise. I have not quite worked that out yet though.

[benz]

Marlow Ropes can do all sorts of fancy custom stuff with factory-tapered cores, changing weave patterns, and adding different materials in as the line progresses. The guys there are very friendly and helpful, and even if your budget won't allow for custom-woven halyards (I'm sure they're $$$$$), they might have some good suggestions.
But surely the spar maker is in position to give sufficient clearance? It seems that if one is designing a 5/16" hole, a 3/4" hole would not be hard to achieve?

[allene]

I should add that I don't want to compromise the mast design or change it to accommodate the splice and besides this 1/2 inch thick splice is really fatter than I want so I will be figuring out how to reduce the bulk one way or the other. I don't know how much until I hear from the builder but my initial goal was 7/16 so if that is OK, I will reduce to that. If not, 3/8 would be OK as well. Probably between these would be ideal. This will be a DIY project in any event.

But the point of my post was to see if anyone had gone all the way to constant diameter.

[Stumble]

I haven't, and kind of suspect it can't be done while retaining the line strength. But a custom tapered line isn't a bad idea. They do it a lot of OD race boats, and it doesn't add much to the cost. At some point they just start adding more fibers and weave them in. For the Opti sheets it adds about $10 to cost of the sheet.

[allene]

The spar maker just said 1/2 inch was OK so I might leave it the way it is or take a strand or two out. First I am going to load it up and see if it settles in a bit.

Still intrigued about the possibility of making a constant diameter 12 strand splice. The advantage of course is that I can have Dyneema for low stretch and the polyester Tenex for the winch all in a single line.

[allene]

I have two thoughts on the constant diameter 12 strand splice. I think the way I did it on my trial piece is viable although cuts the strength in half. This is probably acceptable for something like the halyard I was building where the line is sized for very low stretch and is at least twice as strong as it needs to be. One would have some abrupt cuts that whipping could cover.

Short of that, I think one could make the splice very long and basically weave each strand from one side into the other with a long enough overlap that the load is transferred and strength is maintained.

But reweaving the line would be incredibly difficult so if I wanted to make the halyard constant diameter I would just remove half strands from each section for 60 to 72 diameters and do a end for end splice and realize that I lost at least half the strength. But as there are no rope clutches in my application and the mast can take 1/2 inch line, I am good with a standard end for end splice.

Just a note. I was expecting the splice to end up being 7/16 based on the volume of the two 5/16 lines. But the outer braid is not tight so there are lots of gaps between the strands. So instead of the outer braid taking up 1x its volume, it takes up 1.6 times. I could understand 1.2 times as that is the amount of change in length of the outer braid. That drove me nuts for some time until I noticed all the air. Maybe with load and over time the strands will flatten and the diameter will shrink.

[allene]

I have two thoughts on the constant diameter 12 strand splice. I think the way I did it on my trial piece is viable although cuts the strength in half. This is probably acceptable for something like the halyard I was building where the line is sized for very low stretch and is at least twice as strong as it needs to be. One would have some abrupt cuts that whipping could cover.

Short of that, I think one could make the splice very long and basically weave each strand from one side into the other with a long enough overlap that the load is transferred and strength is maintained.

But reweaving the line would be incredibly difficult so if I wanted to make the halyard constant diameter I would just remove half strands from each section for 120+ diameters and do a end for end splice and realize that I lost at least half the strength. But as there are no rope clutches in my application and the mast can take 1/2 inch line, I am good with a standard end for end splice.

Just a note. I was expecting the splice to end up being 7/16 based on the volume of the two 5/16 lines. But the outer braid is not tight so there are lots of gaps between the strands. So instead of the outer braid taking up 1x its volume, it takes up 1.6 times. I could understand 1.25 times as that is the amount of change in length of the outer braid. That drove me nuts for some time until I noticed all the air. Maybe with load and over time the strands will flatten and the diameter will shrink.