Are there true advantages to sta-loc standing rigging?

[Paul L]

If you tension the larger wire to only the tension used on smaller wire you will tend to have sloppy leeward shourds. So if you go up in size you go up in tension load. At least thats how I understand it.

[rbk]

The tensions are a percentage of the working loads of the wire generally around 15%, bigger wire = higher working loads = higher tension. Too big a wire could compromise the chain plates but you'd have to really go up in size I would think.

[Jim Cate]

If you tension the larger wire to only the tension used on smaller wire you will tend to have sloppy leeward shourds.

Why? Shrouds get sloppy because the windward wires stretch under load, and wire stretches in a sorta linear fashion with stress. Bigger wire stretches less under a given stress increment, so the leeward shrouds should remain tighter, not looser with a given load.

jim

[a64pilot]

Remember all steel stretches, it’s actually how a bolt tightens, it stretches that is why it comes loose slowly and not all at once when you turn it with a wrench.
Also steel is more elastic than rubber, it’s why springs are made from steel.

Somebody is going to challenge me on that, but I’m pretty sure it’s correct

[Sailmonkey]

Originally Posted by a64pilot

Remember all steel stretches, it’s actually how a bolt tightens, it stretches that is why it comes loose slowly and not all at once when you turn it with a wrench.
Also steel is more elastic than rubber, it’s why springs are made from steel.

Somebody is going to challenge me on that, but I’m pretty sure it’s correct

The head studs on ship engines are “torqued” by stretching the studs with hydraulic jacks then running the nuts down. But I wouldn’t say steel is more “elastic” than rubber. That it contains more energy per unit of stretch, sure. But more “elastic”, I don’t believe is the correct descriptor.

[a64pilot]

Try Googling it.
Hint elastic doesn’t mean how far something will stretch before breaking.
That’s from memory, I guess I should google and read, but a steel spring can be stretched or compressed millions of times and return to its original size and not lose any strength.

[Paul L]

Originally Posted by Jim Cate

Why? Shrouds get sloppy because the windward wires stretch under load, and wire stretches in a sorta linear fashion with stress. Bigger wire stretches less under a given stress increment, so the leeward shrouds should remain tighter, not looser with a given load.

jim

I think you are correct. I was thinking of this backward.

[RaymondR]

Originally Posted by Cheechako

Trying to think this through. Why would larger wire need to be tensioned higher? A certain load is needed to keep the mast straight, it seems to me that smaller wire MAY need more tension actually, depending on what load is required.
Larger wire will stretch less under a shock load, so may be safer in an extreme situation. For most column failures, the inability to keep the slender column straight is what makes them fail.

Your instincts are sound Cheechako. Engineers describe keeping the column straight as "in column" and when the column goes out a whole new set of bending parameters come into play.

I think it was a Swiss bloke called Euler who came up with the mathematical expression to describe column behaviour, hence the Euler formula which goes something like"

Critical buckling stress equals two times Pi times Elasticity time Moment of Inertia times a column factor divided by the length squared. The nasty in this is the length squared bit which any increase in length decreases the allowable stress very quickly because of it's exponential nature. The column factor is a variable which depends upon the treatment of the ends and whether they are fixed or not.

So having less stretchy wire will keep the column "in column" under higher forces.

I think in engineering terms the elasticity of a material is one of those length divided by difference in length things something like stress divided by strain and for steel it's something like 28,000,000 psi and for rubber a very small quantity.

Stronger, less stretchy wire is going to be able to keep your mast up better but it will at least influence other behaviour characteristics of the boat.

[fish53]

I splice and make my own galvanized rigging for less than one stalok so don't ask me.

[Sailmonkey]

Originally Posted by a64pilot

Try Googling it.
Hint elastic doesn’t mean how far something will stretch before breaking.
That’s from memory, I guess I should google and read, but a steel spring can be stretched or compressed millions of times and return to its original size and not lose any strength.

Well, I’ll be dammed.......

https://learning.knoji.com/why-is-st...ng-to-physics/

The rest of us now need to start using the term elastic correctly according to physics.

[Neptune's Gear]

I don’t go oversized, despite sailing south of 40 deg for many years. Do you think that you know more than the naval architect who designed your boat and rig? The mast step, mast, chainplates and vessels structure are designed in balance. Rigging wire is very seldom the cause of dismasting. It’s the terminals, chainplates etc that are more likely to fail. Bigger size wire adds windage and weight aloft for no benefit. It’s better to lose a rig than have it rip out a chainplate, and possibly sink? Bigger wire is just moving the failure point somewhere other than where the designer intended.

[a64pilot]

Originally Posted by Sailmonkey

Well, I’ll be dammed.......

https://learning.knoji.com/why-is-st...ng-to-physics/

The rest of us now need to start using the term elastic correctly according to physics.

It’s my understanding it’s also why a steel ball bounced on a hard surface, like steel for instance will bounce higher than a rubber ball.

[a64pilot]

Originally Posted by Neptune's Gear

I don’t go oversized, despite sailing south of 40 deg for many years. Do you think that you know more than the naval architect who designed your boat and rig? The mast step, mast, chainplates and vessels structure are designed in balance. Rigging wire is very seldom the cause of dismasting. It’s the terminals, chainplates etc that are more likely to fail. Bigger size wire adds windage and weight aloft for no benefit. It’s better to lose a rig than have it rip out a chainplate, and possibly sink? Bigger wire is just moving the failure point somewhere other than where the designer intended.

Your correct, assuming of course that the sizing of the wire was actually picked by the Engineer, often the Accounting dept. has a great say in picking rigging, winches etc size, especially if a company is barely treading water as many do occasionally.

It’s one reason to buy a “better” built boat, cause the rigging etc is considered oversized, but in fact may just be correctly sized, but when compared against some others it appears oversized.

[waterman46]

Originally Posted by Don C L

Yeah calculating the stretch on new wire and figuring that in, when you know the exact length is kind of a trick too. There’s a mathematical formula for it I bet, can’t remember now. I’ll have to ask my rigger, he put a head stay on my boat with NO turnbuckle and nailed the length. Pretty impressive.

I replaced the swaged standing rigging on my mainmast using combination of StaLoc and Norseman, and went one size larger on most of it. I did not make any allowance for stretch, I simply laid out the new wire on a lawn beside the old wire, pulled on both to get them straight and made the new terminal to terminal exactly same length. It worked perfectly, the turnbuckles after rig tuning, seemed to be in the same thread position as the old.

[Paul L]

Originally Posted by Neptune's Gear

I don’t go oversized, despite sailing south of 40 deg for many years. Do you think that you know more than the naval architect who designed your boat and rig? The mast step, mast, chainplates and vessels structure are designed in balance. Rigging wire is very seldom the cause of dismasting. It’s the terminals, chainplates etc that are more likely to fail. Bigger size wire adds windage and weight aloft for no benefit. It’s better to lose a rig than have it rip out a chainplate, and possibly sink? Bigger wire is just moving the failure point somewhere other than where the designer intended.

Agreed. Up sizing rigging is often a rookies view of what will make their rig safe. It is a rare case that the original wire is too small.