An alternative method for tensioning dyneema rigging

[Benz]

Originally Posted by peb

D you have a picture of the second method? I don't quite understand (I am rather slow at my age).

I haven't taken a pic, but perhaps I will soon and post it on my website. Looks like the world is ripe for an instructional slideshow on lashings. Trouble with posting anything is that as soon as you do, you learn a better way to do it--there's still much to discover in this soft rigging world.

[Benz]

Originally Posted by s/v Jedi

No, that is only part of the function and your alternative does not replace the frapping knot.

When a strand in a lashing breaks due to damage or a manufacturing fault, the frapping knot will prevent the whole lashing undoing itself and keeps the lashing intact with the strands that didn’t break and should still have more than enough strength to carry the load.

Also, after you hitch off the tail of the lashing, you take the Spanish windlass off, which transfers the load to the tail of the lashing which gets pulled tight and thus gives a little (or more) and now the tension is off.

For all but the smallest cruisers, a turnbuckle makes much more sense. Today the rigger posted about new fittings that look like Stalok fittings except are for Dyneema, making things very easy as they provide the same attachments as stainless steel rigging.

I'm puzzled that anyone would think it possible/likely that a strand of a lashing should break. I've never known one to nor heard of one doing so. If you buy dyneema from any reputable manufacturer, and size the lashing properly for the load, the contingency of losing one leg seems really remote.
If you find the tail of the lashing gives a little after the spanish windlass is removed, you can simply overtighten the lashing a little to begin with. Again, this is easy with a come-along on the fall of the lanyard.
I have no objection to round seizings (this 'frapping knot'); they have their place and I've made scores of them--it's just that it's time-consuming to seize a lanyard that you may want to tune a little after you take up some of the other shrouds.
For a lashing who's only purpose is to interface between a shroud and a turnbuckle, huge tension is not necessary, since the turnbuckle takes up the tension--why bother pulling it bar-tight and seizing it?
Anyway Jedi, I don't want to start a pissing match here--there's lots of ways to do things, and the best is often the one that works for you. I'm just sincerely puzzled about the frapping thing. As for connecting shrouds to turnbuckles with lashings, perhaps that's a topic for another thread, since this one is about lanyards without turnbuckles.

[s/v Jedi]

Originally Posted by Benz

I'm puzzled that anyone would think it possible/likely that a strand of a lashing should break. I've never known one to nor heard of one doing so. If you buy dyneema from any reputable manufacturer, and size the lashing properly for the load, the contingency of losing one leg seems really remote.
If you find the tail of the lashing gives a little after the spanish windlass is removed, you can simply overtighten the lashing a little to begin with. Again, this is easy with a come-along on the fall of the lanyard.
I have no objection to round seizings (this 'frapping knot'); they have their place and I've made scores of them--it's just that it's time-consuming to seize a lanyard that you may want to tune a little after you take up some of the other shrouds.
For a lashing who's only purpose is to interface between a shroud and a turnbuckle, huge tension is not necessary, since the turnbuckle takes up the tension--why bother pulling it bar-tight and seizing it?
Anyway Jedi, I don't want to start a pissing match here--there's lots of ways to do things, and the best is often the one that works for you. I'm just sincerely puzzled about the frapping thing. As for connecting shrouds to turnbuckles with lashings, perhaps that's a topic for another thread, since this one is about lanyards without turnbuckles.

I am not talking about connecting shrouds to turnbuckles with lashings… only you are doing that (and Chotu :-). I was talking about the yachtrigger who posted about new fittings from Blue Wave that are like Stalok fittings but for Dyneema.

When a lashing fails it is always on just one leg, so for every failure a disaster is prevented by using a frapping knot. How often a lashing fails I don’t know, maybe there’s data somewhere? We put two hose clamps on hoses under the waterline in case a hose clamp fails but how often this happens I don’t know either. The point is that the consequences for when these components fail are so severe that we put safeties and backups in.

If I would be tightening shrouds with a come-along, I would use two so that I can get the tension on each side correct before securing the lashing. Over tightening as anticipation on some slip afterwards must be sheer impossible to achieve balanced tension and a straight mast over both port and starboard shrouds if doing one by one.

[peb]

Originally Posted by Sos

Was it an aluminium or plastic one you tested?

If the ali ones are strong enough it would be easy to buy them as supplied and then get them polyester powder coated. Would last ages then.

Aluminium

[sailingharry]

Originally Posted by s/v Jedi

How often a lashing fails I don’t know, maybe there’s data somewhere? We put two hose clamps on hoses under the waterline in case a hose clamp fails but how often this happens I don’t know either. The point is that the consequences for when these components fail are so severe that we put safeties and backups in.

Two hose clamps below the water line preventing a failure is so unlikely that it is not even recommended by ABYC, a body notoriously focused on unlikely events!
(Note, this is not a criticism ABYC. Organizations like this exist to find and prevent accidents and death.)

[s/v Jedi]

Originally Posted by sailingharry

Two hose clamps below the water line preventing a failure is so unlikely that it is not even recommended by ABYC, a body notoriously focused on unlikely events!
(Note, this is not a criticism ABYC. Organizations like this exist to find and prevent accidents and death.)

You only have one hose clamp? You never seen two hose clamps used?

[sailingharry]

Originally Posted by s/v Jedi

You only have one hose clamp? You never seen two hose clamps used?

No, most if not all of mine came with two. It is almost universal. It's sort of interesting that in many cases, many people object to all kinds of ABYC "Chicken Little" rules, but in this case we all know what ABYC doesn't.
ABYC has clearly thought about double hose clamps, because they require them on exhaust hoses. One can only surmise that in this case they have evaluated the likelihood of failure and determined that the additional safety is not worth the cost of a hose clamp.

[s/v Jedi]

Originally Posted by sailingharry

No, most if not all of mine came with two. It is almost universal. It's sort of interesting that in many cases, many people object to all kinds of ABYC "Chicken Little" rules, but in this case we all know what ABYC doesn't.
ABYC has clearly thought about double hose clamps, because they require them on exhaust hoses. One can only surmise that in this case they have evaluated the likelihood of failure and determined that the additional safety is not worth the cost of a hose clamp.

I’m not sure, I think they simply don’t have a plumbing document? I can’t find anything about hose and hose clamps in their thru-hull document…

[Benz]

Originally Posted by s/v Jedi

I am not talking about connecting shrouds to turnbuckles with lashings… only you are doing that (and Chotu :-). I was talking about the yachtrigger who posted about new fittings from Blue Wave that are like Stalok fittings but for Dyneema.

When a lashing fails it is always on just one leg, so for every failure a disaster is prevented by using a frapping knot. How often a lashing fails I don’t know, maybe there’s data somewhere? We put two hose clamps on hoses under the waterline in case a hose clamp fails but how often this happens I don’t know either. The point is that the consequences for when these components fail are so severe that we put safeties and backups in.

If I would be tightening shrouds with a come-along, I would use two so that I can get the tension on each side correct before securing the lashing. Over tightening as anticipation on some slip afterwards must be sheer impossible to achieve balanced tension and a straight mast over both port and starboard shrouds if doing one by one.

By that logic, we would end up with two shrouds each place for redundancy (some have suggested it). While I appreciate redundancy, I prefer to engineer something to be strong enough to to worry about. So I have ONE chainplate per shroud; ONE shroud per chainplate; ONE engine--you get the picture. My lanyards are four passes of 5mm SK78--I'd drop it to three and still have more strength left than the shroud itself, but the Colligo deadeyes have four holes.
My concern with seizing the lashing legs is that until the system has been stressed by hard sailing, the legs may not have faired themselves around into sharing equal load: it seems like you'd be making the contingency you fear more likely with it's cure! When making covered loops, we're careful not to put any stitching or obstructions through the core, at least until it's been pre-stressed on the test bench, so all the turns can equalize.
Anyway--redundancy has its place, but we must not get tied up in knots about it.

[s/v Jedi]

Originally Posted by Benz

By that logic, we would end up with two shrouds each place for redundancy (some have suggested it). While I appreciate redundancy, I prefer to engineer something to be strong enough to to worry about. So I have ONE chainplate per shroud; ONE shroud per chainplate; ONE engine--you get the picture. My lanyards are four passes of 5mm SK78--I'd drop it to three and still have more strength left than the shroud itself, but the Colligo deadeyes have four holes.
My concern with seizing the lashing legs is that until the system has been stressed by hard sailing, the legs may not have faired themselves around into sharing equal load: it seems like you'd be making the contingency you fear more likely with it's cure! When making covered loops, we're careful not to put any stitching or obstructions through the core, at least until it's been pre-stressed on the test bench, so all the turns can equalize.
Anyway--redundancy has its place, but we must not get tied up in knots about it.

I’m sorry, I think I need to retire from this thread as your comments make no sense to me. Covered loops are not under tension so completely different than lashings on shrouds which are. When you pretension a covered loop before locking the core, this is more like the lashing on a tensioned shroud.

Also, many capshrouds are supported by intermediates and lowers, forestays by cutter- and baby-stays, aft stays sometimes by aft lowers and/or running backstays and the engine is a backup for your sails… auxiliary engine.

Nothing you write makes sense to me so I’ll leave the thread to you

[jcapo]

Originally Posted by s/v Jedi

You only have one hose clamp? You never seen two hose clamps used?

A surveyor commented on my double clamps below the waterline saying the only place he cared about double hose clamps was on engine exhaust hoses.

[Benz]

Originally Posted by s/v Jedi

I’m sorry, I think I need to retire from this thread as your comments make no sense to me. Covered loops are not under tension so completely different than lashings on shrouds which are. When you pretension a covered loop before locking the core, this is more like the lashing on a tensioned shroud.

Also, many capshrouds are supported by intermediates and lowers, forestays by cutter- and baby-stays, aft stays sometimes by aft lowers and/or running backstays and the engine is a backup for your sails… auxiliary engine.

Nothing you write makes sense to me so I’ll leave the thread to you

One last try: multi-pass covered loops and lashings both depend on all the legs sharing the load: the more even the strain on every leg, the more strength the whole system retains. When you put a tight seizing on the lashing, as per the Youtube vids, if every leg wasn't evenly loaded when the seizing went on, they have no chance to equalize, as they would if the tail was simply hitched off and no seizing applied.
Rather than promote redundancy, the 'frapping knot' seems to encourage failure.

[s/v Jedi]

Originally Posted by Benz

One last try: multi-pass covered loops and lashings both depend on all the legs sharing the load: the more even the strain on every leg, the more strength the whole system retains. When you put a tight seizing on the lashing, as per the Youtube vids, if every leg wasn't evenly loaded when the seizing went on, they have no chance to equalize, as they would if the tail was simply hitched off and no seizing applied.
Rather than promote redundancy, the 'frapping knot' seems to encourage failure.

That’s the point Benz, when you construct a covered loop there is no tension before you pretension it, but when you tighten a shroud with a lashing and balance the load over the legs of the lashing like demonstrated in all the videos I linked then the lashing is as balanced as it’s gonna be and the frapping knot secures it. You simply can’t compare the two with a straight face

Your method creates imbalance when you tie the tail end, increasing the risk of a failure of a leg in the lashing. This imbalance is what everyone always warns against and you promote it.

[Benz]

Originally Posted by s/v Jedi

That’s the point Benz, when you construct a covered loop there is no tension before you pretension it, but when you tighten a shroud with a lashing and balance the load over the legs of the lashing like demonstrated in all the videos I linked then the lashing is as balanced as it’s gonna be and the frapping knot secures it. You simply can’t compare the two with a straight face

Your method creates imbalance when you tie the tail end, increasing the risk of a failure of a leg in the lashing. This imbalance is what everyone always warns against and you promote it.

I contend that a shroud is pulled harder when sailing than when tuning, and that pull will make all the legs of the lanyard even out and share the load more evenly. If you lock them up before the ultimate load has been placed on them, you negate their ability to render around when fully loaded until they all pull evenly.

That even pull is what's important for the strength of the system. It's also why I like deadeyes such as Colligo makes, where each pass has a dedicated hole, so the passes of line aren't all squeezed together and riding over each other around the radius they're turning. I also prefer less passes of thicker lanyard line; my optimum is 3: beyond that, the friction is really a drag. Even with a 4-pass system, I often take out the last leg while tensioning, so I'm tensioning on 3, then thread the last leg and hitch it off while holding the rest racked up in a spanish windlass.

[zachduckworth]

I’m curious to hear if there were ever any follow-up experiments with the wire tighteners. I may be buying some Dux and hardware to try this out myself soon, in situ on my boat. As someone else pointed out there are some very robust aluminum versions of this device available.