This is *crazy* !

[s/v Jedi]

More research: stitching instead of splicing. I have done stitch & seize successfully in the past, where the seizing only failed after many years (more than 10 years) of UV exposure.

https://www.practical-sailor.com/sai...ad-of-splicing

[nelly]

Originally Posted by s/v Jedi

When you use a reputable rope manufacturer like Samson, New England Ropes, Yale Cordage, Marlow etc. then I am convinced their tables are correct because it has been tested and demonstrated many times incl. on countless YouTube videos and by members of this forum.

Did you see that my calculations limit the load on these lines to a maximum of 20% and much less for most of the time? This is what is recommended for maximum longevity.

We have broken lines. A genoa furling line, a genoa sheet and almost a main sheet which was down to half the fibers. But in every one of those cases it was a problem with chafe (wrong block installed by previous owner) or the lines should have been replaced earlier.

We never had a line less than 10 years old break and we have had very tough sailing, incl. through named storms.

I am not saying that they are lying - just that the numbers they give are (often) in lab settings. That's all. I trust their products, absolutely! I have used Samson and New England, probably the others as well.

Do you have a YouTube video of someone breaking Samson rope eyesplice to eyesplice and reaching 100% breaking strength? If so that's great info to have, I wasn't able to find one.

The 20% number I think is a different conversation, but yes did see that, and yes I think intuitively this makes sense. I would not want to load my lines past 20% of their advertised breaking strength!

I have never, ever broken a line on the boat. Hardware, yes absolutely. Not a line. But you have been sailing for a lot longer than me!

My "interpretation" of "lines don't break" is that "hardware breaks first" - and the loads you calculated (while the math I'm sure is 100% correct!) are never actually seen by lines, for various reasons. I think we agree on this point.

[s/v Jedi]

Originally Posted by odonnellryan

I am not saying that they are lying - just that the numbers they give are (often) in lab settings. That's all. I trust their products, absolutely! I have used Samson and New England, probably the others as well.

Do you have a YouTube video of someone breaking Samson rope eyesplice to eyesplice and reaching 100% breaking strength? If so that's great info to have, I wasn't able to find one.

The 20% number I think is a different conversation, but yes did see that, and yes I think intuitively this makes sense. I would not want to load my lines past 20% of their advertised breaking strength!

I have never, ever broken a line on the boat. Hardware, yes absolutely. Not a line. But you have been sailing for a lot longer than me!

My "interpretation" of "lines don't break" is that "hardware breaks first" - and the loads you calculated (while the math I'm sure is 100% correct!) are never actually seen by lines, for various reasons. I think we agree on this point.

I don’t have any videos at hand, but I remember that a proper, tapered eye splice often exceeds the 95% claims and the line breaks somewhere else, like in the loop which would be another weak point.

I’m afraid we actually do see high loads now and then. The numbers from the calculations are for static loading, but these are of course exceeded for shock loads like tacking, gybing etc.

[nelly]

Originally Posted by s/v Jedi

I don’t have any videos at hand, but I remember that a proper, tapered eye splice often exceeds the 95% claims and the line breaks somewhere else, like in the loop which would be another weak point.

I’m afraid we actually do see high loads now and then. The numbers from the calculations are for static loading, but these are of course exceeded for shock loads like tacking, gybing etc.

Very, very different than my understanding, that's for sure! See here:

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

He tests a LOT of dyneema - and no this stuff isn't different than what we're using

Rarely, if ever, does eye-to-eye break anywhere except the eye or the taper.

This isn't "lab conditions" but that's the point - real world use is not lab conditions either.

Does Samson publish their testing methodology?

His videos are a great resource and gives you some context for "real world" and yes - salt, dirt, oil, sunscreen, other boat stuff (paint, wax ... ) UV, etc.. do have impacts - but often varying levels of impact.

Also, some cool videos showing different (and useful) ways to splice dyneema which I need to try out on a few projects...

Yes dynamic loading is scary and something I think about. But I know that my hardware is almost too big to manage in most cases, and my lines are sized above that. I don't care about weight - not even on the jib sheets. Not really.

Oh - and you'll actually see in this case that the Marlow D12 Max 99 (this is stronger dyneema) actually breaks HIGHER than they advertise - but that isn't always the case!

[donradcliffe]

Back in the day, breaking a sheet was a common occurence, and we as race crews had standard ways of recovering. If you are using the new high tech lines and sizing them for handling comfort and use in self tailing winches and jammers, breaking a line is pretty rare unless you have neglected or chafed it.. Its much more likely the hardware or the sail attachment will fail. Try an uncontrolled jibe in 35 knots with a full main and you will pieces of the traveler car and mainsheet blocks all over the cockpit.

[BG305]

Originally Posted by odonnellryan

I am not saying that they are lying - just that the numbers they give are (often) in lab settings. That's all. I trust their products, absolutely! I have used Samson and New England, probably the others as well.

Do you have a YouTube video of someone breaking Samson rope eyesplice to eyesplice and reaching 100% breaking strength? If so that's great info to have, I wasn't able to find one.

The 20% number I think is a different conversation, but yes did see that, and yes I think intuitively this makes sense. I would not want to load my lines past 20% of their advertised breaking strength!

I have never, ever broken a line on the boat. Hardware, yes absolutely. Not a line. But you have been sailing for a lot longer than me!


My "interpretation" of "lines don't break" is that "hardware breaks first" - and the loads you calculated (while the math I'm sure is 100% correct!) are never actually seen by lines, for various reasons. I think we agree on this point.

Not sure if this is what you were looking for.

https://youtu.be/P3M10COESTQ

[Joli]

We've broken sheets racing, typically it's the #3 blade. The angles are extreme.

We've yet to break any lines on this boat but our jib sheet is about done after 3 years. We've end for ended it but the inner core (dyneema) is failing and will need replacement, probably next year. You can calculate sheet loads but that's static. Sailing through waves cycles the line, sails and gear at much higher loads then are calculated. Harken calculates our jib sheet at around 9,000 lbs at 35 knots, the lines we use are rated at around 21,000 lbs.

Whatever you think you need, buy bigger.

[fxykty]

Originally Posted by s/v Jedi

How can you only have 3,771lbs clew tension with the third reef at 50kts wind? I am over 4,000lbs at 45kts already, while my main is only 65 sqm vs 86 sqm for yours plus you have more roach? I have 35 sqm left with the third reef… is your 3rd reef that much more aggressive?

Our 3rd reef is 26.5sqm.

[s/v Jedi]

Originally Posted by Joli

We've broken sheets racing, typically it's the #3 blade. The angles are extreme.

We've yet to break any lines on this boat but our jib sheet is about done after 3 years. We've end for ended it but the inner core (dyneema) is failing and will need replacement, probably next year. You can calculate sheet loads but that's static. Sailing through waves cycles the line, sails and gear at much higher loads then are calculated. Harken calculates our jib sheet at around 9,000 lbs at 35 knots, the lines we use are rated at around 21,000 lbs.

Whatever you think you need, buy bigger.

My 16mm sheets are in that category and served us well in the trade winds in the Caribbean, but now in the light airs around Florida and the Bahamas, those sheets are so heavy that they made the sail unusable.

So now I’m adding 10mm sheets and strip them for light weather sheets, plus add twings

[s/v Jedi]

Originally Posted by fxykty

Our 3rd reef is 26.5sqm.

That explains it all

It makes sense now that I think of it. We simply ditch the mainsail and continue on reefed mizzen and jib, where the 3rd reef in your main is the last step, taking the role of a trysail

[Lee Jerry]

Originally Posted by fxykty

I just did the numbers for our cat.

FYI, Samson says the formula is not applicable to multihulls.

[Lee Jerry]

Originally Posted by odonnellryan

Very, very different than my understanding, that's for sure! See here:

He tests a LOT of dyneema - and no this stuff isn't different than what we're using

Rarely, if ever, does eye-to-eye break anywhere except the eye or the taper.

This isn't "lab conditions" but that's the point - real world use is not lab conditions either.

Does Samson publish their testing methodology?

His videos are a great resource and gives you some context for "real world" and yes - salt, dirt, oil, sunscreen, other boat stuff (paint, wax ... ) UV, etc.. do have impacts - but often varying levels of impact.

I think that is very much lab conditions. How could it be more so? I'm sure it's quite similar to how everyone, including Samson, does their testing.


I expect Samson tests to some standard, either ASTM or ISO or the like. It shouldn't be too hard to find which one. Also, much of their commercial products are class approved (ABS, DnV, etc.), which is a one measure of quality.

[s/v Jedi]

Originally Posted by Lee Jerry

I think that is very much lab conditions. How could it be more so? I'm sure it's quite similar to how everyone, including Samson, does their testing.


I expect Samson tests to some standard, either ASTM or ISO or the like. It shouldn't be too hard to find which one. Also, much of their commercial products are class approved (ABS, DnV, etc.), which is a one measure of quality.

Yes, I need to find the time to watch that video. A few skips showed breakes at the loop as well, plusI saw inadequate tapering as well. Tapering is more than cutting a strand at a time; the strands themselves must be tapered as well.

But I also think thise breaks will be close to the rated tensile strength?

Last but not least, this is not the line we use. I can not bring myself to spend the money on SK99 and even if I would, chandlers only stock it in small diameters.

It’s better to watch Amsteel Blue tests, which is in reach of cruisers and also the core of Warpspeed II double braid.

[fxykty]

Originally Posted by Lee Jerry

FYI, Samson says the formula is not applicable to multihulls.

That’s correct. Other calculators (Harken for eg) say that they’re for average monohulls with Dacron sails, so also not applicable to a ULDB or very stiff boat with high modulus sails.

For a generic formula like this I’m not sure type of boat matters - the load on the sail is the same regardless of righting moment as it defines load based on sail area for a particular wind strength. A monohull sail will generate the calculated load and then heel, reducing the load. The sheet will still need to handle the calculated load defined by the formula, but will mostly be working at less than the calculated load. For a multihull, the sail will generate calculated load and maintain that load, hence the sheet (and all hardware) will need to work at that highest level. So multihullers size for peak calculated loads, while Jedi and other monohullers can size for median loads, knowing that there will be occasional higher peak loads with lower safety factors.

That’s why standing and running rigging on a multihull is typically larger than for an equivalent length monohull. For example, a Harken System C batten car is good for monohull mains up to 180sqm, for multihulls it’s only up to 140sqm. Though type of cat matters too - a Hanse 548 has cap shrouds larger than ours (14mm vs 12mm) and requires 65 ratio winches, while we are happy with 54 ratio.

So I could add a 20% fudge factor to the formula for the cat. If I choose high modulus lines for my running rigging then my loads are still within 5:1 safety factors of lines that are sized for the calculated loads and are too small to handle easily. So upsizing for handling takes care of that fudge factor.

[s/v Jedi]

The problem is that calculations lead to equipment failures on catamarans in the past. The source of those problems turned out to be shock loading, caused by the stiffness of the catamaran that doesn’t heel to absorb these loads.

So they tried to adjust calculations, but in the end they gave up because they simply failed to find the correct formulas. This wasn’t just for running rigging but also for standing rigging. The solution was actual testing and upgrading until it stopped failing.

So for cats it is very important to know the original sizes for all rigging wires and ropes used. You can still upgrade to high tech, but make sure the new choice at minimum equals the specs for the oem rigging. I have met cat sailors who came from monohulls and wanted to go to smaller sheets based on their experience with monohulls… that’s a bad strategy.

For companies like Samson they simply don’t want to deal with the issue and only offer guidelines for monohulls, referring cat sailors to manufacturer specifications.