Dyneema rigging on a budget

[BigNut]

Originally Posted by andreas.mehlin

...and/or/but...

Wouldn't it be possible to skip the thimble on the chainplate and the mast tang and put the splice directly to a clevis pin? Let's say you are going with a 1/2" shroud, wouldn't it be alright with a 5/8" clevis pin? The line is not tensioned many percent of its breaking strength so the line would handle that I guess?

Marlow recommends a D/d of at least 8:1

[andreas.mehlin]

Originally Posted by BigNut

Marlow recommends a D/d of at least 8:1

Attachment 224944

Interesting!

Another thought....using a sheave instead of a thimble?

[longjonsilver]

Originally Posted by andreas.mehlin

Interesting!

Another thought....using a sheave instead of a thimble?

You mean like the sheave of a block?

jon

[Benz]

Originally Posted by andreas.mehlin

Interesting!

Another thought....using a sheave instead of a thimble?

You'd have a hard time reaching the hole on the sheave with the jaw of the turnbuckle, since it's usually in the center. If you need an 8x bend radius, 8x 3/8" is about three inches, so the jaw would have to have 1 1/2" clearance, plus the diameter of the line, putting it at nearly 2"
You could drill an offset hole in a solid sheave, though. I wonder what solid aluminum sheaves cost? I wonder if Delrin sheaves would handle the load.

[longjonsilver]

Originally Posted by Benz

I wonder what solid aluminum sheaves cost? I wonder if Delrin sheaves would handle the load.

Both of these have ideas have gone thru my mind as well. Maybe some phone calls Tuesday would clear this up....

[andreas.mehlin]

Originally Posted by Benz

You'd have a hard time reaching the hole on the sheave with the jaw of the turnbuckle, since it's usually in the center. If you need an 8x bend radius, 8x 3/8" is about three inches, so the jaw would have to have 1 1/2" clearance, plus the diameter of the line, putting it at nearly 2"
You could drill an offset hole in a solid sheave, though. I wonder what solid aluminum sheaves cost? I wonder if Delrin sheaves would handle the load.

True! Something to consider...

Although, I do have some plan not to use turnbuckles...but the toggle, or what ever is used, needs to have enough depth/length.

The question is also, Would I need toggle connected to the mast tang or would it be a possibility yo connect directly to my tang? Many times tangs are used to be forgiving to the stiff stainless fitting/cables/swages...but the dyneema is pretty flexible

[Benz]

Originally Posted by andreas.mehlin

True! Something to consider...

Although, I do have some plan not to use turnbuckles...but the toggle, or what ever is used, needs to have enough depth/length.

The question is also, Would I need toggle connected to the mast tang or would it be a possibility yo connect directly to my tang? Many times tangs are used to be forgiving to the stiff stainless fitting/cables/swages...but the dyneema is pretty flexible

I'd suggest at the upper end removing the existing tang and using an eye bolt with a eye nut at the other end. Essentially you'll have two rings like earlobes sticking out of the mast. Splice the upper end of the shroud around a closed thimble, then simply lash the thimble to the ring. Inspect it from time to time.

[thinwater]

Originally Posted by BigNut

Marlow recommends a D/d of at least 8:1

Attachment 224944

A sheave and a splice are totally different in several ways. The material also matters (8:1 is too small for wire rope, for example). Not a valid reference point for eye splices. Marlow would agree.

[fxykty]

Originally Posted by andreas.mehlin

True! Something to consider...



Although, I do have some plan not to use turnbuckles...but the toggle, or what ever is used, needs to have enough depth/length.



The question is also, Would I need toggle connected to the mast tang or would it be a possibility yo connect directly to my tang? Many times tangs are used to be forgiving to the stiff stainless fitting/cables/swages...but the dyneema is pretty flexible

There’s Colligo products for all of this, if you’re not opposed to buying rather than building for this kind of hardware.

The connection to the mast can be done with Cheeky Tangs. https://www.colligomarine.com/produc...line-thru-bolt. If you think-fittings they have cheeky tangs for that too.

No toggle is needed because the fibre stay itself is flexible, unlike wire. Here’s our cap shroud and running backstay at the mast.



At the bottom we use a Colligo standard terminal to connect to the turnbuckle.



The standard terminators have slots for the lashing lines. These are nice as they prevent the lashing lines getting jammed against each other and loaded unevenly. https://www.colligomarine.com/produc...-11-13mm-black and for the chainplate end https://www.colligomarine.com/produc...e-distributor-

[Benz]

Originally Posted by thinwater

A sheave and a splice are totally different in several ways. The material also matters (8:1 is too small for wire rope, for example). Not a valid reference point for eye splices. Marlow would agree.

Thanks for clarifying--I hadn't seen that the recommendation was for a running sheave, not for a thimble. 8:1 is pretty huge for a thimble. We routinely do 1:1 radiuses in dyneema eyes when it's a halyard deadend going to a clevis pin at the masthead. The failure point is never there.
I wouldn't do that for shrouds, where I'd simply use the proper-sized thimble for the rope diameter, but I lose very little sleep over bend radiuses.

[andreas.mehlin]

Originally Posted by thinwater

A sheave and a splice are totally different in several ways. The material also matters (8:1 is too small for wire rope, for example). Not a valid reference point for eye splices. Marlow would agree.

Sorry but I don't understand what you are saying...
8:1 no enough? Well, then all of Colligos hardware are disqualified...

clarify please

[Benz]

Originally Posted by fxykty

There’s Colligo products for all of this, if you’re not opposed to buying rather than building for this kind of hardware.

The connection to the mast can be done with Cheeky Tangs. https://www.colligomarine.com/produc...line-thru-bolt. If you think-fittings they have cheeky tangs for that too.

No toggle is needed because the fibre stay itself is flexible, unlike wire. Here’s our cap shroud and running backstay at the mast.

Attachment 225047

At the bottom we use a Colligo standard terminal to connect to the turnbuckle.

Attachment 225048

The standard terminators have slots for the lashing lines. These are nice as they prevent the lashing lines getting jammed against each other and loaded unevenly. https://www.colligomarine.com/produc...-11-13mm-black and for the chainplate end https://www.colligomarine.com/produc...e-distributor-

Great pics! It seems that the OP is going after the very lowest budget DIY solutions, though. Sometimes the biggest part of DIY is knowing when to just throw down and order the right parts. I get it--I buy used, and modify, and adapt, and build my own of many things; I've been poor: but sometimes the elegant solution is worth the $$$. I hope he sees that before too long...

[BenBowSirocco]

FlyingNut40

There is good reason these professional companies have stopped using the non-heat treated dyneema. Essentially they run out of adjustment long before the creep stops and so they have to cut and re-splice, which means starting all over again.
They have spent many years, tons of time/effort/money as well to develope the DUX and other refined dyneema blends/processes to create a usable and reliable rigging product.
It has nothing to do with strength, its all about stretch and creep. The molecules of the polyethylene (plastic) linear chains that are made by 10's of thousands into bundles and then woven together to create "dyneema" are all out of whack when first produced. Heating them to specific temperatures and then apply a specific known load to them while traveling over heated rollers causes these molecular chains to "smooth out" or "settle in".
Its in many ways similar to heat treatments of steel: what you are doing is dramatically changing the molecular structure of the material to create better properties for its intended use.

This happens to non-treated dyneema over time and use from the cyclical loading/unloading of the rig and causes the dyneema to gain length, this is called: creep.

Now, there is some background from early experimentation where after setting up the finished splices, they (professional riggers) were loading the finished piece with hydraulics to twice normal rigging loads or something- this would flush out quite a bit of the splice stretch. Although, they found did not cure the creep. It allowed them to set up a boat and go sailing though.

The plan to use turn buckles is very convenient for tuning and taking up the splice stretch, but the problem will be that the turn buckle will bottom out over time. Running lashings, you can lash and re-lash and re-lash... But they are an entire new area for stretch/creep and slack to exist.


If your goal is to save money by spending time (which is always a related equation). I believe you MIGHT be able to buy yourself a quality drill press (a proper mill would be best of course) and carefully set up a series of jigs to make copy cat parts of Colligo equipment.
I believe they use T6061 which is a heat treated hardened aluminum alloy. You can cut this on a band saw with a quality wood band and drill it with any quality steel cutting drill bits. Be VERY careful not to heat it. To edge your blanks you can use a high speed router with carbide wood bits- perhaps with a wet towel to keep the part cool.

This process would be very time consuming, but I would imagine if you looked hard enough you could find some off-cuts/scraps of the proper aluminum plate. After they are finished, acid etch the aluminum and paint them.

If you order DUX from the source importer (Northeast Canada I believe), the price is quite reasonable.
It is not a good idea to build a rig from un-treated dyneema- you will spend countless hours and it will not work as it should.
Read the blogs and posts of professional riggers and head their experience.

If you would like custom "dog bones" (the rigging eyes bolted to the mast described by Ben) to bolt aluminum discs into, I would be willing to help you by sending you DXF files to have laser cut if you send me dimensions.

[longjonsilver]

Originally Posted by BenBowSirocco

If you order DUX from the source importer (Northeast Canada I believe), the price is quite reasonable.

You mean Hampidjan? They are here in Dartmouth NS

jon

[BigNut]

Originally Posted by thinwater

A sheave and a splice are totally different in several ways. The material also matters (8:1 is too small for wire rope, for example). Not a valid reference point for eye splices. Marlow would agree.

Oh boy, my apologies if I muddied the water. I need to read a bit mor3 on this, it seems. Thanks, thinwater.