Precourt Thimbles and Pulling Amsteel through itself

[Tripp26zoom]

Hello

I am rerigging the backstay on my Tripp 26 using Precourt round thimbles and 1/4 inch amsteel. I intend to create a cacade with 4 working legs of 1/4 inch amsteel hanging off the 1/4 inch amsteel running down from the top of the mast.

I have been using Precourrt round thimbles and mobius brummels at the working end of the cascade. 4 round thimbles to create the cascade with 4 lines of amsteel running through the thimbles.

I was experimenting with my setup and thought about using the round thimbles at the dead end to attach to the boat, but 4 thimbles would be pretty bulky at the attachment point .

Then I struck on the idea of pulling the amsteel through itself and setting the thimble inside the loop that I create in the amsteel. I would then be creating 2 legs of the cascade out of one continous line. One round thimble at each end of the amsteel with a mobius brummel and then a round thimble towards the centre of the line as the attachment point. By setting the middle thimble at something other then equidistant from the ends I can create the 4 different length legs out of 2 continuous lines with only 2 attachment points in the cascade.

My questions are:

If I pull the amsteel through itself and around the round thimble, am I lowering the breaking strength of the line.

Is there a recommend method for pulling the amsteel through itself so that the loop I create for the round thimble doesn't open up in the course of sailing and maintain the strenght of the line. I was practicing mobius brummels on an old piece of line a few days ago and realize now that I can create a fixed loop in it without tucking the end of the line but am I maintaining the strength of the line.

Thanks
.

[Brion Toss]

Hi,
Sorry to have been so long in replying, but sometimes these questions vanish at the bottom of my screen. If I understand you correctly, you are talking about cinching a thimble in place with a loop formed by passing the end through the standing part. Seems like a really bad idea. How about just side-splicing eyes to the standing parts? There'd be minimal deformation of the standing part, and you could even use a smaller diameter line for the added bits. Brummel and bury.
Fair leads,
Brion Toss

[Tripp26zoom]

Hi Brion

Thanks for your response and your patience

I am a bit unclear as to what your are suggesting with respect to side splices - could you clarify. Or maybe suggest a better way to do this.

I probably wasn't clear in my description as to what I was trying to do. So bear with me as I try to explain.

I wanted to have create a 4 leg cascade to add to my backstay. There is single line leading from the mast head.It ends about 9 feet from the deck and there was a block at the end of this line. Originally there was an 8:1 purchase system . There were two lines fixed to one side of the stern of the boat , one was lead to the block 9 feet up and the second feed through the other with ablock attached and it was controlled on the others side of the stern with a double ended control line that also splits and runs forward to either side of the cockpit for the maintrimmer to control.

I thought about replicating the old system but with a cascade with 4 seperate lines, each of different lengths with a eye splice and precourt thimble at each end . I would shackle the 4 ends to the attachment point and then have an eye splice with precourt thimbles at the working end, with each line fed through the next precourt thimble at the working end to form the cascade.

After testing my design I realized that having 4 precourt thimbles at the attachment point was pretty bulky. I thought about eye splicing the 4 lines directly to the attachment point which is a metal loop, but was concerned about the wear and tear on the line. All the pressure would be on the same point on the lines. I also though about adding smaller thimbles to the eye splice.

Then I hit on this other idea, making the cascade out of 2 rather then 4 lines.

For Line A I would lead the line up through precourt thimble 0 which has been mobius brummeled to the backstay hanging 9 feet above the deck ( I am replacing the block at 9 feet aboe the deck). I would then mobius brummel with a tuck precourt thimble 1 at one end of the line A. I would then mobius brummel precourt thimble 2 into the line towards the centre point of the line, on the other side of thimble 0 . Then I would lead the other end of Line A back through thimble 1 and then add thimble 3 to the other end of the line A with a mobius brummel and a tuck.

I would then take Line B and feed it through thimble 3 and to line B add thimble 4 with a mobius brummel and tuck. On the other side of thimble 3 towards the middle of line B add thimble 5 with a mobius brummel and no tuck. Then take the other end of line B and thread it through thimble 4 and add thimble 6 with a mobius brummel and a tuck.

I would then attach the cascade to the fixed point on the boat with a shackle through precourt thimble 2 and 5. My thinking was that having the precourt thimbles at the attachement point would prevent wear and tear on the lines and would be strong.

When I first wrote to the site I was concerned about "pulling" amsteel through itself and whether I was signficantly weakening the line. If all I am doing is creating a mobius brummel midway through the line I kind of think I am not significantly weakening it, unless the tuck counts for a lot of the strength.

The other aspect is I have two legs of the cascade working off the one thimble with a shackle through it at the attachement point. Is this where you are concerned about deformation?


Is this what you thought I was doing and advising against.

Thank you again for your assistance and patience.

[allene]

I hesitate to chime in here as I barely follow what you are trying to do but if I understand that you want to put a thimble in the center of a line that sounds like a really bad idea. The whole strength of a splice is from the load on the line being nicely on the line and the line stays there because of the friction of the buried end with the outer part. As load is put on the line, the outer part grips the inner part. The more load the tighter the grip. That is why you do things to keep the splice from coming apart when there is no load. Putting a thimble in the center of a line is going to put the loads at some odd angle or offset from the line itself. My guess is that something very bad would happen if you loaded it up.

If I am misunderstanding what you are doing, just ignore what I said

Allen