Puzzle

It is time to announce the winner of our most recent Rigging Puzzle. But first I’ll mention that if you’d like to see previous puzzles, along with a whole bunch of essays and reports from the field, be sure to visit our Blog. And you might also want to take a look at our Front Page, where, in addition to information on rigging services, you can find details on upcoming events, including our 3-day rigging classes, the Seattle Boat Show, a link to our catalog, and news about an upcoming trip to Tasmania. Okay, on to the Puzzle!

Last week’s challenge drew a near-record number of entries, from people in a wide variety of rigging interests. You folks are  obviously enthusiastic about loading up hardware. To see the Puzzle, click HERE.

Because the  Puzzle stipulated manufacturer’s recommendations, we will start with Harken, the maker of the diamond-shaped fixed padeye we used. In their catalog Harken says, “For maximum strength, always align fixed padeye bails to the load.” They then give working strengths and breaking strengths for loads applied at various angles, with the highest strength (1) being a vertical load, and the lowest (3) a horizontal load. This is true for all padeyes and eyebolts, because the fasteners are stronger in tension than in shear, and because no leverage is applied when the load is straight up. The trouble is that the only pertinent illustration for this in the regular Harken catalog is this one:

Too many people, including quite a few Puzzle entrants, seem to think that pulling at point 1 produces the greatest strength, regardless of the plane of the pull. The warning in the catalog text, it seems, is easily overlooked. Harken does have a confusion-eliminating illustration for this issue, but for some reason they only show it in their industrial catalog. Here it is:

In the real world, slightly off-angle loads can be difficult to avoid, but they must be minimized, and the puzzle’s arrangement #1 is definitely bad for fixed padeyes.

Harken also makes a folding padeye, similar to the Wichard model we used for the puzzle, and Harken  takes pains to note that, “Folding padeyes differ from conventional padeyes in that the load should be perpendicular to the hinge and bail instead of in line with it. The strongest positions are with the D-ring vertical or leaning toward the fold-down position, which focuses the load on the side anchored with two screws.”

Harken doesn’t have a comparable illustration for their folding padeyes, but Wichard includes this one with every padeye:

Note that the smiley faces apply whether the bail is angled in either direction; I take this to mean that the difference in strength might not be all that significant, despite Harken’s advice.

The lower right frowny face tells us it is a bad idea to pull in line with the bail on a folding padeye, and this agrees with Harken’s recommendation. The idea here is that you would be applying a point load on one side of the fitting, instead of a long bearing along the length of the hinge. This is the pull shown for the folding padeye in arrangement #2, so that one is out.

Note also that the upper right frowny face calls our attention to the fact that there is a limit on how far the bail can articulate towards the two-fastener side. Go too far, and the bail crunches against the base of the padeye, producing some very unfavorable leverage, torque, and point loading. Therefore, when you are installing folding padeyes, see if there is an articulation limit on one side or the other, and then install it so the side with the greatest range of motion is facing the most likely range of load angles. If you have an application where you might need full articulation in both directions, you need a different padeye. In the first iteration of the Puzzle, I had the bail right down at the base of the padeye in arrangement #3, and sharp-eyed readers Ken Ferrari and Robert Salnick saw this. The second version of the pictures showed the folding padeye on the fully-articulating side, and no one was disqualified because of this detail.

The upshot of all this is that arrangement #1 is good for the folding model, but bad for the diamond, and the opposite is true for arrangement #2. The correct answer, then, is arrangement #3.

Congratulations to all of you who chose #3. And congratulations likewise to everyone who gave it a shot. Our winner, randomly selected from the pool of correct entries, is … Tom Dixon! Congratulations, Tom. Let me know which version of Falling you would like to receive — print, audio, or ebook — and what circumference and rope diameter soft shackle you would prefer. For everyone else, thanks for all of your thoughtful responses.

If you didn’t win the drawing, but want a copy of that book, it is available from Amazon as well as iBooks. If you would like an autographed print copy, be in touch with Sue at our shop, by writing to catalog@briontoss.com.

There’s lots going on at briontoss.com. Scroll to the bottom of this page for details.

The Rigging Puzzle this time is about padeyes, and how to load them. In the pictures below, one padeye is a classic diamond pattern from Harken, and the other is one of Wichard’s nifty folding models.  We loaded them three different ways, all with the leads rising slightly up from the horizontal, and only one of those ways complies with the manufacturers’ recommendations for maximum strength, for both padeyes.  So what’ll it be, picture number 1, picture number 2, or picture number 3?

If you think you know the answer, send it to puzzle@briontoss.com, or reply at the bottom of this page. Feel free to kick this around online, but it won’t count unless you submit an answer. We’ll draw the winner randomly from the pool of correct answers.

The prizes this time: one of our high-strength Spectra soft shackles (suitable for securing to your favorite padeye) and a copy of my book Falling, about the perils and rewards of working aloft. The book is available as a paperback, as an ebook, or as an audiobook, the latter narrated by yours truly.

Entries must be here by noon Pacific Time, January 21st. We will announce the winner on January 23rd. Good luck!

Arrangement 1, top view

Arrangement 1, side view

Arrangement 2, top view

Arrangement 2, side view

Arrangement 3, top view

Arrangement 3, side view

In other news, if you are going to be at the Seattle Boat Show, I’ll be giving a series of talks there about various aspects of rigging. And I will soon be sending reports in from, of all places, Tasmania, at their huge, semi-annual Australian Wooden Boat Show. And finally, we will be once again bowing to popular demand and will be giving another 3-Day Rigging Workshop this April, at our loft in Port Townsend. Still some spaces available, but these workshops fill up fast. For information on all of this, and more, visit briontoss.com

In our most recent puzzle, we asked how much additional tension our rigger Julia Briggs could apply to a line by “sweating” it sideways. Here is the  puzzle, with accompanying video:

Sailors and other rope users are familiar with the process of sweating or swigging up a line: pulling sharply sideways on the fall of a purchase, above the belay point to gain a bit of slack, then quickly transitioning to a downward resolution, so that slack can be taken up at the belay point. The combination of leverage and impact-loading allows you to get more tension than you could by simply pulling down on the line. But the question is: how much more?

In the video below our rigger Julia Briggs is sweating a line in our shop. The line has been set to a starting tension of 200lbs.

Julia weighs 140 lbs.

The line is attached to a load cell that has been set up to read the maximum tension achieved.

So here is the puzzle: how many additional pounds of tension did Julia impose?

Congratulations to everyone who ventured an answer; there was some serious head-scratching going on out there. But the people who got closest to the actual answer tended to be the ones who used actual math, so to explain things, here is a simple-enough-for-my-level-of-comprehension explanation:

The maximum reading on that load cell was the result of two factors: how much force Julia could exert; and the angle that the rope formed at the peak of her pull.

Because she pulled very sharply, she exerted a shock load (accelerated load), which could easily be at least as much as her body weight, depending on how fast she was moving, how elastic the materials were, and how far she managed to deflect the line. For details on calculating shock loads here is a good site: sciencing.com/calculate-shock-load

As you can see from the video, Julia did not deflect the line more than a few inches, but this is actually a good thing in terms of getting a high load cell reading, because her leverage increases as the angle decreases, varying with the sine of the angle formed at either end of the line. If this sounds counterintuitive, there are lots of real-world applications for the idea. For instance, if you are a guitarist, you know how easy it is to “bend” a note up, tightening an already tight string by pushing sideways on it as you pluck it. Now try to get the same effect by pulling in line with the string (without using the lever known as a tuning peg), and you will see how powerful your leverage was. If you are a sailor, you know that as shroud angles diminish, tension on the shrouds goes up. And if you are an industrial rigger, you know that loads on sling legs go up as sling angles decrease towards the horizontal. For more on this, see the “Standing Rigging Design and Materials” chapter of  The Rigger’s Apprentice.

In our example, we started with an initial tension of 200 pounds, minimizing the ultimate deflection, and thus maximizing the potential leverage. Then Julia maximized the effect of her weight with the classic sailor’s Two-six-HEAVE, technique, building up her acceleration to an explosive final pull. And she maximized the shock load with good body mechanics, so that she was pulling perpendicular to the line, arms fully-extended and braced, on that final pull. The result was a load of 563 pounds (!), after deducting the initial 200 pounds. That’s right, she exerted almost four times her body weight on that line. In the real world, we are usually working with more elastic materials and bigger deflections, but you can see why sweating a line can be such a valuable force multiplier.

Given all the variables, it is not surprising that the answers were all over the place, and no one got within 10 pounds of the result, but several of you were quite close, so I expanded the tolerances, and am awarding prizes to everyone who got within 150 pounds, high or low. So congratulations to Nels  Backstom (672 pounds), Ian Duff (420 pounds), a reader identified only as “nopain” (480 pounds), CarlyP (670 pounds), Captain Mike (whose entry was closest, at 600 pounds), my dear friend Ben Stockwell (644 pounds), and Seng (715 pounds, which is 2 pounds over, but what the heck). All of you folks, please be in touch to let me know whether you want the audiobook or the ebook version, and whether it should go to you, or to be a gift.

For those of you who were outside the envelope, it is really easy to get a copy of Falling by other means, by going to Apple or Amazon.

In other news, those in the Seattle area can find me at the Seattle  Boat Show later this month, giving a series of talks about a variety of rigging topics. After that, I’ll be heading to Tasmania for some talks at the wonderful Australian Wooden Boat Show.

Fair leads,

Brion Toss

This week we have a two-stage puzzle. Answer either stage correctly, and you qualify to win one of our Point Hudson Fids, good for splicing up to 5/8” 3-strand rope, and also for a variety of sizes of braided rope that need tuck splices

Answer both stages correctly and you qualify to win the above Fid and the larger version, good for up to 1 1/8” 3-strand rope, and the larger tuck-splice braids.

Stage One: In the picture above, there is something very wrong, as in could-cause-serious-injury wrong. What is it?

Stage Two: Hang on a moment, it is possible that things are not as bad as we think. What other (obscure) explanation is there that would reduce the problem to an annoying installation error? Hint, old-time racing sailors and their cruising contemporaries will have an advantage in figuring this one out.

If you think you know either or both answers send them to puzzle@briontoss.com. Entries must be in by noon Pacific Time, Monday, July 9th. We will draw the winners at random from the pool of correct entries. Please don’t post your answers on line; if you are right, you will give things away, and if you are wrong you might be needlessly embarrassed.

Computer unpleasantnesses have delayed posting this puzzle. Sorry for the delay.

As always, you might enjoy a stroll through back-issues of this Blog, and through our online Store.

Fair leads,

Brion Toss

PS,

Starting with this post, our subscribers get all content a day ahead of everyone else. If you’d like that kind of preferential treatment, scroll down and sign up.

In the picture above, our friend Alison is pulling on the fall of a purchase. She is also pulling on me, and I am the object she is trying to move. Disregarding friction and angles, what is the total mechanical advantage? Hint: notice that Alison is standing on a skateboard that is in line with the pull.

If you think you know the answer, send it to puzzle@briontoss.com, or leave a comment below (please don’t give away the answer by posting it online). The winner, randomly selected from the pool of correct entries, will receive an autographed copy of The Rigger’s Apprentice. Entries must arrive by noon Pacific Time, Monday, June 11^th. The winner will be announced on Wednesday, June 13^th.

As always, I invite you to catch up on all the back-articles and -puzzles on my Blog. The current article is called Not Falling Far, Part 2: The Bounce Test.

In other news, time is running out to sign up for our 3-day  “Rig Your Boat” workshop, here in Port Townsend.

Fair leads,

Brion Toss

Last week’s rigging puzzle, was about a puzzled rigger. Here’s an abbreviated version of the scenario:

On a boat with shrouds that attach to deck athwartships (directly out from the mast), the uppers were set up first, to a desired tension. Then the intermediates were set up. Then the rigger checked the tension on the uppers, and found that they were significantly slacker than they had been. What had happened?

For the full-length version of the puzzle, see Here

Up to speed? Good. Now for some answers.

By far the most popular response – and the most frequent cause of this exact thing happening in the real world – is that the mast’s support gave way. On a deck-stepped mast it could mean that the deck compressed, or that the compression post lived up to its name, or that the part of the hull that the compression post landed on had given way. “Squishy mast step” is how Steve Willie described it, and I urge you all to check for this problem; more than a few times we have undertaken the simple task of tuning a rig, only to discover that because of this problem there wasn’t going to be enough throw in the turnbuckles.

It is also possible for the base of the mast itself to give way, especially on keel-stepped masts, where rot (wood) or corrosion (aluminum or steel) can be at work in the moist environs of the bilge. This could literally be happening right under your feet, so lift up those sole boards and take a close look, regularly.

Many entries noted that if the mast isn’t going down, the deck or chainplates might be coming up. The latter is a possibility with a keel-stepped mast where someone forgot to set up the tie rod belowdecks adjacent to the mast. Not all keel-stepped masts have or need tie rods, but in the absence of a nearby structural bulkhead, for instance, they are the only thing that can keep the deck from buckling upwards from the compression loads imposed by the shrouds, and sometimes also from the loads on blocks for halyards that are led aft. If the middle of the deck goes up, the sides of the hull can go in, and the rig can slacken.

On very flimsy hulls, the portions of the hull that the chainplates are pulling up on can deform. This is “humping” as opposed to hogging. Hogging has nothing to do with rig tune. If a hull is humping, and if the rig is being tuned correctly, it means that the hull is not up to the task of sailing.

Some entrants had more dramatic suggestions. For instance, here are two of David Randle’s many suggestions:

The shrouds connect to the mast via T-ball fittings, and one of the uppers wasn’t fully seated in its slot but slipped in while he was working on the intermediates.

and,

The mast was not fully seated on the step while tensioning the uppers, but finally settled all the way down after adding the tension of the intermediates.

These can happen, and when they do, they tend to do so with a serious bang. If this happens to you, get that mast back out and see what broke from the impact.

Several people suggested that induced bend might be the culprit, and this can happen, especially if you are starting from the top, and the backstay is also tightened at the same time. This is because almost every mast nowadays is thinner side-to-side than fore-and-aft, precisely because designers are counting on all the shrouds to prevent buckling in the lateral plane. If the shrouds are loose, but the stuff up top is tight, the mast can buckle, dramatically. How do I know this? Never mind. But the larger dimension fore-and-aft is what stiffens the mast in that plane, as there are no shrouds and spreaders to support it there.

It is also easy to get changes in tune simply by tightening shrouds unevenly, as several entrants pointed out.

A couple of people thought that the mast got shorter for every pound of tension applied. The idea is that when the uppers were tensioned the mast gets shorter, and when the intermediates are tensioned it gets shorter still, resulting in slack on the uppers.

Technically almost any material under compression gets shorter, including the stuff you make masts out of. But the kind of loads we are talking about would probably not produce shortening that would be possible to measure, let alone affect the tune of the shrouds. Think about it: if the mast compressed that much under shroud loads, then tuning would be a matter of gradually taking up on the standing rigging, trying to reach the desired tension, until the mast was a pancake.

There were lots of other ideas, and I’ve shown some of my favorites below, but now it is the time to announce our winners.

First, the randomly-chosen contributor of at least one valid response is …

Captain Pete Gustafson! His no-nonsense entry is as follows:

How about a soft or collapsing mast step? It could also be the deck straps that keep the deck from lifting are loose.

Congratulations, Pete, you are now the proud owner of my Rig Tuning DVD, or credit towards anything else in our catalog, as well as a copy of Selden’s excellent rig tuning guide. Be in touch to tell me where to send them.

The winner of our other prize, for the greatest number of somewhat realistic answers, goes to … Henry Schultz! Congratulations Henry, I actually/barely thought that 12 of your 13 entries had at least some merit. For your prize, you get exactly the same things Pete does. Be in touch.

Honorable mention to David Randle, who had just one valid answer less than Pete.

And now for a randomized list of further possible answers, taken from all entries. Thanks to everyone who took the time and effort to throw a light on this topic.

Temperature variance in the rig when adjusted.  Example, the uppers were done when the temperature was 35 and intermediates were done at 85 degrees.

The uppers stretched under the initial load after being tensioned, while he was fiddling with the intermediates. [This can happen with brand new wire]

He had installed a Corian step to replace some much pitted aluminum and with the combined strain of the shrouds there was molecular creep letting the mast down a little.

Throughbolts on the mast elongating the hole. [A surprisingly common problem. Likewise we see throughbolt failures. [Both problems can readily lead to dismastings]

One or more of the uppers’ swages (wire), rod ends (rod), or splices (composite) was/were failing and slipped. [Poorly-seated mechanical terminals can allow wire to move significantly before everything settles into place. Similarly, synthetic rigging must be stretched hard at first, to remove constructional elongation]

He neglected to pin the turnbuckles of the uppers, and while he was fiddling with the intermediates, the upper turnbuckles backed off.

His tension gauge was inferior or perhaps he used it incorrectly and all the readings were wrong anyway. [Words of wisdom. Just because you have one of those gauges doesn’t mean you know how to use it]

The uppers were adjusted at low tide with the keel resting on bottom thereby pushing the keel step mast higher the normal position when free floating.  Intermediates were done when floating. [Not a likely scenario, true, but correct in principle. It is why we never tune on the hard]

The rigger was at a wedding the night before and still pretty looped when he tuned the uppers. [My favorite]

Thanks again to everyone who entered. You have provided us all with food for thought.

If you would like to learn more about the principles and practice of rig tuning, you can find that abovementioned DVD at our Online Store and on Vimeo

Newsworthy note: our June Rig class is filling up, so if you were hoping to attend, contact catalog@briontoss.com soon.

This Friday, watch for “The Bounce,” the second installment in our “Not Falling Far” series.

Fair leads,

Brion Toss

A client recently called for a consultation on tuning. He has a 30-something-foot contemporary sloop, double-spreaders, with all the shrouds even with the mast (athwartships). That might sound impenetrably salty for the non-sailors here, but it just means that there are three shrouds (lateral stays) on each side of the mast. The upper two shrouds go over spreaders, which are just struts that create a good angle to the mast. The lowermost shrouds go straight to deck. Checkstays and babystay omitted for clarity. See my illustration above, which simultaneously shows the rig’s configuration and explains why I use actual illustrators for my books.

My client had started by tuning the uppermost shrouds first. This is a red herring. Please do not be distracted by it. But I would always tune the lowermost shrouds first on this rig.

Not distracted? Good. So he got the tension he wanted on the uppers, and went to tension the next ones down, the intermediates. After he had done this, he re-checked the tension on the uppers, and was puzzled to discover that they were significantly slacker than they had been. This is not supposed to happen.

And here is the puzzle: How many possible reasons can you think of for why those upper shrouds lost tension? You only need to come up with one believable explanation to qualify for a Fabulous Prize, but we will have a separate, Also Fabulous Prize for the person or group that can come up with the most answers that, in my utterly subjective opinion, make some kind of sense. Your rigging can be made of wire, rod, or synthetics, but to reduce variables let’s say the mast is aluminum. You can assume your rig is anywhere in the world, at any time of year you like.

Deadline for entries is noon Pacific Time, Monday, May 28^th. Send your entries to: puzzle@briontoss.com

If you have a hankering to read prose or other puzzles from me, there are some treats in store for you in the Blog section of our site. You can click on the highlighted word, or scroll to the bottom of this page. Also down there you can join the over 1,000 other people who receive email notifications when I post new items. 

Our June Rig Your Boat Class is filling up fast, so if you have been thinking about coming, don’t delay.

Oh yes, and we have a superlative Online Store. Go shopping there. Now.

Fair leads,

Brion Toss