Dyneema rigging on a budget

[Michael Pope]

I would very tactfully ask you to check on a usable Yield strength for the particular Stainless steel you are using rather than an ULTIMATE Tensile. and and ask about how many cycles at 80 to 90 degrees F,

Are the thimbles cast or wrought?? Tested?

I have been disappointed in the past do not want you to be !
The lashings are multiple layers thick so inner layers are in compression at approaching 90 deg , and tension, and being Plastic by definition they will creep and become a smaller cross section. All easily dealt with by using an appropriate factor for how many layers you end up using,

Looks appealing I would use a slightly flattened thin wall SS tube of a size to slip down over the whole assembly to protect against Caribbean Swashbucklers swords and U.V . And away you go.
You might hate me for asking this but how does Lightning effect a rig like this when it is wet and salty?? Umm Interesting!! Mike Pope

[mikedefieslife]

Originally Posted by Benz

Lashings are cheaper and lighter and don't ever crevice corrode, gall, or bind. The whole system (on my boat) requires only one clevis pin per shroud. And it looks better. The question is why are people still buying turnbuckles when lashings exist to make our lives better?

I’m not sure about that. Turnbuckles are usually used for two rigging changes so thats 20-30 years lifetime. I’ll give you weight but so low down on the deck it’s negligible. Price is similar for the coligo marine fittings.

[Benz]

Originally Posted by flyingnut40

Thanks for the input Ben. what size of bow shackle would have a favorable radius for the rope? I expect the chainplate hole to be 7/16" or maybe even 1/2" TBD.

I would feel better if I could eliminate the dogbone to simplify the rig.

I did a closer inspection of the Suncor SS thimbles and it seems the cross section is just under .2 sq " and SS 316 has a tensile strength of 80,000 lbs, so

.2 x 80,000= 16,000 x2 legs of the thimbal.... they should be good for 32,000 lbs. in tension but likely a bit less due to point loading.


I'll check out your site for that info.

Under no circumstances should you use a thimble in tension--please just abandon that idea. The sk78 lashing line you'll use for your lanyards requires a minimum of 1:1 bend radius, so anything bigger is a bonus. If your shackle (doesn't have to be bow: Ronstan and Wichard both make High Test D shackles), is 7/16" and your lanyard is 3/16", well, there you go.
The test bench I have access to is at a place where I do subcontract work--I can use it for limited personal research, and of course I use it all day to set in splices for them, but to wrongly load a thimble and break it would raise eyebrows.

[Breaking Waves]

There really are not any 'mysteries' left related to Dyneema.

Use a 1.2x or better bend ratio
Deform the fiber/weave absolutely as little as you can while splicing (and end taper very finely)
Load multiple legs as equally as you possibly but still anticipate they will not be equally loads and adjust for than in working load (note there are some tricks to minimize this issue but they are not frequently used)
Use loose (to avoid deforming weave) lock stitching to avoid low load slipping
Anticipate constructional elongation, especially in your splice buries, and anticipate long term creep
Lashings vs turnbuckles is a convenience issue and really depends on boat/rig size/load - turnbuckets are rather easier to adust and lock in place at higher loads.

[flyingnut40]

Thanks for all the inputs. I agree that using a thimble in tension without the fail safe lashing is dubious. I'm still curious about the breaking strength.... but I digress.
As for lightning I'm led to believe it's a non issue. Stainless wire is a better conductor than wet rope.

[longjonsilver]

Please take all my comments with the understanding that i am learning as i go and am no expert.

i find that the Rigging Doctor has a great video series:

https://www.youtube.com/watch?v=MctpeFJ4AuY

Including how to tie off the lanyard using his frapping knot.

Zingaro uses a thimble thru a shackle and it appears to make hard spots as the bearing surface is too small between the thimble and the shackle. i question how this would work in the long run.....

jon

[Benz]

^^Depends on the specs of the thimble. We often see heavy duty thimbles on 1" or bigger megayacht dinghy tow bridles that have cracked at the top of the bend where point loaded for long periods by a huge Tylaska shackle. The fix is a stronger thimble, perhaps with a welded gusset so it can't flex.
I wouldn't like to point-load a closed thimble with a shackle pin unless it was really beefy--there's a reason they make solid thimbles with holes through which the pin fits perfectly for stuff like that.

[longjonsilver]

Originally Posted by Benz

there's a reason they make solid thimbles with holes through which the pin fits perfectly for stuff like that.

The only ones i have seen in which the pin fits perfectly are the Colligo ones, and someone above cast thimbles in solid bronze. i suppose Lunenburg foundry could cast a run of thimbles in bronze.

[Benz]

Originally Posted by longjonsilver

The only ones i have seen in which the pin fits perfectly are the Colligo ones, and someone above cast thimbles in solid bronze. i suppose Lunenburg foundry could cast a run of thimbles in bronze.

They're rare birds: I've run across a galvanized one as well as bronze. But for the price and availability, I can't see looking further than Colligo.

[longjonsilver]

Disclaimer: i have never done this. i am theorizing how i plan on doing my boat.

First pic is from Rigging Doctor We have the thimble attached to a pin



Here we have a point load on the 12 o'clock point of the pin and the thimble. Is not the pin designed to spread the load from 9 o'clock to 3 o'clock? Is the thimble designed to take all the load at 12 o'clock?

Second pic is from Sailing Zingaro. We have a thimble attached to a toggle.

image url

Here we have the load at 10 o'clock and 2 o'clock on the thimble and the load on the edges of the toggle. Is not the toggle designed to take the load all along its length and not just on the edges? Likewise the thimble is taking the load at only two points.

We know that SS work hardens. When you have point loads, does not the SS work harden faster at those points? Do you want weak points on your thimble, your pin or your toggle? Well, i don't.

So, here is my cheap solution. (Second disclaimer: this is for entertainment purposes only - consult your rigger for better advice)



These are showing the inside of the thimble and an insert machined out of at least 1/4" SS tack welded in place. The first one is for the pin and the second one is for the toggle. This allows for much greater bearing surface between the pin and the thimble or the toggle and the thimble.

(This morning i came upon the idea of using old chainplates for the SS. You already have a hole drilled, which is the hard part of making these inserts. You can drill SS with a 1/2 inch drill motor, good split point drill bits, and lots of cutting fluid. With the money you can save from buying Colligo terminals, you can buy yoself some titanium chainplates...... and use the old SS ones for your inserts)

Next point is that the thimble size used on both Zingaro and Rigging Doctor are smaller diameter than that recommended by Colligo (and Hampidjan) for Dux. As i understand it, Dux requires a greater radius than regular Dyneema, n i notice that Zingaro states Dyneema and Rigging Doctor states synthetic, so i doubt that they are using Dux or any heat treated line. So if you are going to use thimbles you probably should use regular Dyneema. It might stretch more, but hey you are going to use deadeyes and lanyards to adjust your rigging anyway, so you're gonna have to learn to do it yourself. No?

What am i missing here?

jon

[longjonsilver]

I asked Hampdjan: What is the minimum radius of bending for Dynice 75 and Dynice Dux 3/8", 9mm?

The reply from Hampdjan:

In a sling, 1X the PIN diam.

In a grommet, 2X the PIN diam.

Running rope on a sling, 20 D/d.

Can somebody interpret this for me?

[Matt Johnson]

We used Facnor stainless steel thimbles with solid center for our runners. The model for the FX-2500 has, I believe, a pin hole size of 10mm (3/8") and is made for 12mm Torque Rope... but you'd want to verify. Price was about $25 each, but it seems they've gone to $32 now.

https://www.mauriprosailing.com/us/product/FAC0264.html

Ronstan aluminum is slightly more if you're only using 5/16" line:

https://www.mauriprosailing.com/us/p...NRS208040.html

Matt

[Benz]

Originally Posted by longjonsilver

Disclaimer: i have never done this. i am theorizing how i plan on doing my boat.

First pic is from Rigging Doctor We have the thimble attached to a pin



Here we have a point load on the 12 o'clock point of the pin and the thimble. Is not the pin designed to spread the load from 9 o'clock to 3 o'clock? Is the thimble designed to take all the load at 12 o'clock?

Second pic is from Sailing Zingaro. We have a thimble attached to a toggle.

image url

Here we have the load at 10 o'clock and 2 o'clock on the thimble and the load on the edges of the toggle. Is not the toggle designed to take the load all along its length and not just on the edges? Likewise the thimble is taking the load at only two points.

We know that SS work hardens. When you have point loads, does not the SS work harden faster at those points? Do you want weak points on your thimble, your pin or your toggle? Well, i don't.

So, here is my cheap solution. (Second disclaimer: this is for entertainment purposes only - consult your rigger for better advice)



These are showing the inside of the thimble and an insert machined out of at least 1/4" SS tack welded in place. The first one is for the pin and the second one is for the toggle. This allows for much greater bearing surface between the pin and the thimble or the toggle and the thimble.

(This morning i came upon the idea of using old chainplates for the SS. You already have a hole drilled, which is the hard part of making these inserts. You can drill SS with a 1/2 inch drill motor, good split point drill bits, and lots of cutting fluid. With the money you can save from buying Colligo terminals, you can buy yoself some titanium chainplates...... and use the old SS ones for your inserts)

Next point is that the thimble size used on both Zingaro and Rigging Doctor are smaller diameter than that recommended by Colligo (and Hampidjan) for Dux. As i understand it, Dux requires a greater radius than regular Dyneema, n i notice that Zingaro states Dyneema and Rigging Doctor states synthetic, so i doubt that they are using Dux or any heat treated line. So if you are going to use thimbles you probably should use regular Dyneema. It might stretch more, but hey you are going to use deadeyes and lanyards to adjust your rigging anyway, so you're gonna have to learn to do it yourself. No?

What am i missing here?

jon

Please don't do what Zingaro is doing in that picture. While there's probably a margin of safety left due to over-spec (5:1, or five times stronger than the expected load is a common margin for important stuff), as you noted neither the thimble nor the toggle are being loaded properly. That setup is like swearing in church.
But there's a good reason for using pre-stretched dyneema even if you have lanyards: normal dyneema will stretch somewhat as puffs hit the boat, more than heat-set will. So even if only set up with lanyards (which you can get pretty tight if you know how), the rig will still be more stable with DUX or other heat-set.
If you want to modify thimbles according to your drawings there's nothing wrong there--but paying for good SS welding might come out more than buying Colligo or some other similar already made.

[andreas.mehlin]

Originally Posted by longjonsilver

Disclaimer: i have never done this. i am theorizing how i plan on doing my boat.

First pic is from Rigging Doctor We have the thimble attached to a pin



Here we have a point load on the 12 o'clock point of the pin and the thimble. Is not the pin designed to spread the load from 9 o'clock to 3 o'clock? Is the thimble designed to take all the load at 12 o'clock?

Second pic is from Sailing Zingaro. We have a thimble attached to a toggle.

image url

Here we have the load at 10 o'clock and 2 o'clock on the thimble and the load on the edges of the toggle. Is not the toggle designed to take the load all along its length and not just on the edges? Likewise the thimble is taking the load at only two points.

We know that SS work hardens. When you have point loads, does not the SS work harden faster at those points? Do you want weak points on your thimble, your pin or your toggle? Well, i don't.

So, here is my cheap solution. (Second disclaimer: this is for entertainment purposes only - consult your rigger for better advice)



These are showing the inside of the thimble and an insert machined out of at least 1/4" SS tack welded in place. The first one is for the pin and the second one is for the toggle. This allows for much greater bearing surface between the pin and the thimble or the toggle and the thimble.

(This morning i came upon the idea of using old chainplates for the SS. You already have a hole drilled, which is the hard part of making these inserts. You can drill SS with a 1/2 inch drill motor, good split point drill bits, and lots of cutting fluid. With the money you can save from buying Colligo terminals, you can buy yoself some titanium chainplates...... and use the old SS ones for your inserts)

Next point is that the thimble size used on both Zingaro and Rigging Doctor are smaller diameter than that recommended by Colligo (and Hampidjan) for Dux. As i understand it, Dux requires a greater radius than regular Dyneema, n i notice that Zingaro states Dyneema and Rigging Doctor states synthetic, so i doubt that they are using Dux or any heat treated line. So if you are going to use thimbles you probably should use regular Dyneema. It might stretch more, but hey you are going to use deadeyes and lanyards to adjust your rigging anyway, so you're gonna have to learn to do it yourself. No?

What am i missing here?

jon

How about mold some epoxy with fibers of the thimble and clevis pin/toggle?

[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?