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Extavagant Purchase

Puzzle Contest: Extravagant Purchase

Above is a very odd block-and-tackle configuration. Odd, as in has-no-practical-use. But rather than waste it, we’ve made it this week’s Puzzle: What mechanical advantage does this configuration have?

Assume that the sheaves have no friction, that all leads are parallel, and that equal force is exerted, straight down, on both tackle ends (arrows). The uppermost block will move toward the deck.

You don’t need to explain your answer in order to win, but as long as you get the purchase number right, your explanation doesn’t have to make sense, so hey, go for it.

Bonus points if you can approximate the maximum range of motion, up and down, of the uppermost block. Assume that the fiddle block is one foot long, and that the tackles end at the arrows.

Send your entry to puzzle@briontoss.com. The winner will be randomly selected from the pool of correct entries. Deadline for entries is noon Pacific time, Monday, March 19th.

This week’s Fabulous Prize is an autographed first edition of Kaci Cronkhite’s wonderful best-seller, Finding Pax. You can find out more about this wonderful book  here

Note: Painter Frank Hanavan recently posted our Puzzle’s photograph, from Petersson’s book on ship model rigging. It appears to be a nice enough book, but the image, as near as I can tell, shows a configuration that has never been found outside the pages of that book. If such is not the case, please let me know.

 

Whether Helm or Not, 2, The Winner!

Whether Helm or Not, 2, The Winner!

Whether Helm or Not, 2

We had a veritable flood of entries to this week’s Puzzle. To review, it went like this:

Some cruising sailors entered a local race series, and to improve their chances they decided to lighten ship. They took off their diving gear, books, extra clothing, and all the other stuff that tends to accumulate on a cruising vessel. They even offloaded their chain rodes and anchors, figuring they wouldn’t need them to go around the buoys, sent down some spare halyards, and retuned the rig.

The boat was definitely faster after all this, but the sailors were shocked that what had previously been a significant amount of weather helm had suddenly become an alarming amount of lee helm. What factor or factors might have caused this?

Things got off to a slightly rough start when Bob Perry, the Pope of Yacht Design, got the idea that I was promoting an antique method of determining helm balance in the design stage. See, in the old days, naval artichokes saw that getting hulls and sails to balance was tricky, so they came up with rules of thumb to determine how hull area and shape would relate to sail area and shape. The method worked, sort of, but it also produced a lot of vessels with infamously bad helm manners. You can read more about this in Skene’s Elements of Yacht Design. Nowadays things are more refined, and you can find more reliable methods in books like Bob’s, Larsson and Eliasson, and others. The basic idea is that the aerodynamic focal point of the sails (center of effort, or CE) needs to line up pretty closely with the hydrodynamic focal point of the hull (center of lateral resistance, or CLR). In the real world, when the vessel is under way, heel, drag, wind direction, and a host of other variables make this a fairly complex thing to determine. But when it is right, the boat will have a slight tendency to round up. When it is wrong the boat will have a violent tendency to round up (too much weather helm), or a ghastly, terrifying tendency to fall off (lee helm).

I started to detail just the basics of this relationship in preparing this post, and after several pages realized that there was far too much to say just to answer a puzzle. The short form is that, as with the previous puzzle about the effects of running rigging on weather helm, just about everything you do can have a measurable effect on helm balance, inducing either weather helm or lee helm. Just walking around on your boat while it is underway can have such an effect.

One of our more comprehensive entries came from rock star sailmaker Emiliano Marino*, author of The Sailmaker’s Apprentice. He wrote,

“Offhand, I’d say if their ground tackle was stowed up forward and they cleared it out; that would lighten and raise the bow… tending to increase lee helm [this is true for most but not all boats, BT].

“Removing anything aloft would reduce heel, which would also increase lee helm.

“And if, in retuning the rig, they did anything to bring the rig, sails, and sail power forward, that too would increase lee helm. Crew size, weight and position could be a factor.

“Mostly, I’d guess that the weight of all the beer stowed in the lazarette for the race was the culprit.”

To that I would add that, if the rig had been too slack before, the mast would have gone further to leeward, especially when loaded up and on the wind. This is a big cause of weather helm. With a proper tune, the mast would stay further uphill, and this could contribute to moving things toward lee helm. Likewise if the mast had previously been straight, and the tune imposed a proper bend, the CE would have moved forward some.

So, our randomly selected winner from our pool of even remotely correct entries is… Richard Shearley! Be in touch about where to send your Fabulous Prize, which is an autographed copy of Bob Perry’s Yacht Design According to Perry.

Thanks to all of you for your entries! Next week’s Puzzle: Extravagant Purchase.

 

*He also recently added to our list of the tiny number of running rigging pieces that do not, in normal use, affect helm balance: a tripping reef clewline.

 

PS,

My regular Friday blog post this week is Adventures in Maintenance: Achieving Resonance

 

 

 

Puzzle: Whether Helm or Not, 2

Puzzle: Whether Helm or Not, 2

,

Some cruising sailors entered a local race series, and to improve their chances they decided to lighten ship. They took off their diving gear, books, extra clothing, and all the other stuff that tends to accumulate on a cruising vessel. They even offloaded their chain rodes and anchors, figuring they wouldn’t need them to go around the buoys, sent down some spare halyards, and retuned the rig.

The boat was definitely faster after all this, but the sailors were shocked that what had previously been a significant amount of weather helm had suddenly become an alarming amount of lee helm. What factor or factors might have caused this?

Send your answers to puzzle@briontoss.com. The winner, drawn from the pool of correct entries, will win a Fabulous Prize. Deadline for entries is noon Pacific Time, Monday, March 5th.

Photo courtesy of Robert Perry

 

In other news, if you haven’t seen the “Parachutes” story yet, scroll down in the Blog to see both installments. This has been our most-read article here, by a good bit, and I hope you will join in the fun.

This coming Friday we’ll tell the Depression-era tale of the schooners “Commodore” and “Vigilant,” and how they unintentionally thrilled America in a voyage from Hawaii to the Pacific Northwest.

Breaking Stuff, 1: The Winner

Hello all,

A record number of responses to the most recent Puzzle. To review, here it is:

A rigger invested in serious quantities of 1” Nylon and Dacron rope for some destruction testing. The ropes included single-braid, double-braid, and 3-strand. Multiple samples of each type. It was a lot of work to put the splices in, and it had to be done around a full schedule of paying jobs. To make matters worse, the only day that could be arranged for breaking all the pieces was one with heavy, driving rain. So the rigger had to lug all this heavy rope out of the shop, dump it in the bed of a pickup truck for the drive over, and then lug the even-heavier, soggy rope into the testing facility.

At the end of the day, the lab technician said, “I have some good news and some bad news. The good news is that all of your Dacron pieces show very good efficiencies, approaching 100%. But I’m afraid that all of the Nylon pieces broke at about 15% short of that. We did a couple of independent tests with some of the same size and brand rope that we had in-house, and I can tell you that the problem isn’t with the rope.”

“Actually, that is great news all around,” said the rigger, to the surprise of the technician. “My Nylon samples were just as good as my Dacron ones.”

How could this be true?

Some answers attributed the weakness of the nylon to steam, inherent weakness, mismeasurement, and other factors, but our Winner this week — Henry Schultz — kept things simple by saying, “Wet nylon breaks sooner than dry.” This is true, of somewhat short on detail. For a denser explanation, here is the entry from treehouse maestro Ian Weedman:

“Well, I suppose it’s obvious in a couple accounts, still doesn’t mean I’ll get it right though. Both the dacron and the nylon absorb water, albeit at different capacities.  The nylon however, has a distinctly different reaction.  Nylon, being a crystalline polyamide,  is held together by a polarity bond, a  positive and a negative in attraction.  When water finds its way into the rope, it seeks out the charged areas and forces apart the bond.  This results in a weakened connection.  Dry the rope, polarity bond is back.”

I love how Ian starts out in aw shucks mode, and then turns into Richard Feynman. But he is correct, wet Nylon is typically about 15% weaker than dry. Anyway, congratulations, Henry, you have won my “25 Knots” DVD, or equivalent merchandise of your choice. Contact catalog@briontoss.com to arrange shipment.

Next week’s Puzzle: Whether Helm or Not, 2.

Puzzle: Breaking Things, 1

A rigger invested in serious quantities of 1” Nylon and Dacron rope for some destruction testing. The ropes included single-braid, double-braid, and 3-strand. Multiple samples of each type. It was a lot of work to put the splices in, and it had to be done around a full schedule of paying jobs. To make matters worse, the only day that could be arranged for breaking all the pieces was one with heavy, driving rain. So the rigger had to lug all this heavy rope out of the shop, dump it in the bed of a pickup truck for the drive over, and then lug the even-heavier, soggy rope into the testing facility.

At the end of the day, the lab technician said, “I have some good news and some bad news. The good news is that all of your Dacron pieces show very good efficiencies, approaching 100%. But I’m afraid that all of the Nylon pieces broke at about 15% short of that. We did a couple of independent tests with some of the same size and brand rope that we had in-house, and I can tell you that the problem isn’t with the rope.”

“Actually, that is great news all around,” said the rigger, to the surprise of the technician. “My Nylon samples were just as good as my Dacron ones.”

How could this be true?

If you think you know the answer, send it to puzzle@briontoss.com. Correct entries will be eligible for a drawing to win a Fabulous Prize. Deadline for entries is noon, Pacific Time, Monday February 19th.

Puzzle: Whether Helm… or Not, the answers

Last week’s Puzzle gave you two chances to win. Here’s how it went:

Name at least two running rig components that, in normal use, can have a distinct effect on helm balance (inducing or reducing weather helm).

Second way: name at least one running rig component that, in normal use, can not have a distinct effect on helm balance.

As many of you realized, almost every running rig component, in normal use, affects helm balance  This is because most running rig components exist to control and shape the sails, and those sails are, of course, a primary determinant of helm balance. With some lines, like the main sheet or outhaul, this is a given. With others the effect on balance is not as obvious. For instance, the running backstays control forestays’l luff sag, and the main boom topping lift (or the quarter-lifts on a gaffer) can shape the mainsail by lifting the boom in light airs. Thanks for that catch, Carol Hasse.

There are not nearly as many answers to the second question,  at least for a modern Bermudian rig; I only came up with two lines: flag halyards and lazyjacks. But Anna R, in her entry, also listed jib downhauls. Doh. Yes, lowering the jib affects helm balance, but the downhaul is just an optional securing device, taking the slack provided by the halyard and sheets. Any other possibilities? There are certainly some more that you square-rig sailors could have listed…

For a while, I wanted to include, for all applicable rigs, the lazy sheet for the jib or other staysail, but eventually realized that any running rig component, when not in its intended use, has no effect on helm balance.

With all that said, the randomly-drawn winner is … Lee Youngblood! In his entry, Lee wrote, “…It’s all the same system! You do this all the time!  Catch me with the quick answer, outhaul & traveler, but in reality all lines from vang to halyards, and even over-sheeting or easing are part of the balance, all the running rigging, and even the forestay, shrouds, backstay…” That is true, Lee. And your revelation has won you a “Fair Leads” T-shirt. Be in touch with a size and a mailing address

Congratulations to all of you who qualified for the drawing. Next week you will have another chance to win, in a Puzzle about breaking things on purpose.

In other news, you’ll see a new article here on Friday, February 9th. It’s about codes, the kind that keep us from being electrocuted.

We are just back from the grueling 9-day boat show in Seattle, and busy reassembling the shop. When that is done, we will commence scheduling rigging jobs for the Spring. Call us to get on the calendar.

 

 

The Rigging Puzzle: Whether Helm … or not

This week you have two chances to win our Puzzle drawing. First way:

Name at least two running rig components that, in normal use, can have a distinct effect on helm balance (inducing or reducing weather helm).

Second way: name at least one running rig component that, in normal use, can not have a distinct effect on helm balance.

List as many answers as you like, with as much explanation as you like. Incorrect answers will not be counted against you. Correct entries in either category will be eligible for a random drawing for a Fabulous Prize. Send your answers to puzzle@briontoss.com. We will draw the winners at noon Pacific time, February 5th. Winners will be announced February 7th.

The Pirate’s Solution

Hello all,

Last week we posted a Long-John-Silver-ized version of a classic puzzle. Here’s how it went:

Captain Montgomery Hall, the famous pirate, was getting ready to retire, and wanted to be sure he had a qualified successor, so one morning he came on deck with three buckets, their tops covered. As the crew watched he hoisted each of them overhead on separate halyards.

“To be a captain,” he said, “Ye have to be smart. Who amongst ye is the smartest?”

The pirates conferred a bit, and then pushed forward their reluctant choice.

“All right, we’ll see how smart ye are. There’s a gold doubloon in one a’them buckets. There’s a piece of stale, weevily bread in the other two. Pick the right bucket, and you get the doubloon, and the command. Pick the wrong one, ye get yer usual breakfast.”

“But captain,” said the sailor, “No matter how smart I might be, I could only pick the right bucket by luck.”

“Just by sayin’ that, it shows that at least ye aren’t stupid. But pick one anyway.”

So the sailor chose one of the buckets, walked over to the pin its halyard was on, and prepared to cast off.

“Wait just a minute,” said the captain, “Let’s make this more interesting.” And he went over to one of the other pins, lowered one of the other buckets to deck, and removed its cover. Inside was a piece of stale, weevily bread.

“This means that the doubloon is either in the bucket ye chose, or in the third bucket,” said the captain. Could be either one, right?”

“Ye-e-ss,” said the sailor thoughtfully.

“I’ll let ye change your mind, if ye want,” said the captain.

After the sailor considered the matter for a while, he walked away from his first choice, and lowered the third bucket to deck.

So here is the puzzle: Was this the smart thing to do? By changing his mind, did the sailor improve his chances, or make them worse, or did they stay the same?

The solution is tricky, which is why, for this puzzle, any answer right or wrong qualified entrants for the prize drawing. And the winner of that drawing is…. my dear old friend Jim Cole who, along with his spouse Barbara have been cruising the South Pacific recently. Jim is an actual rocket scientist, but even his answer wasn’t quite correct. But as promised, here is my utterly subjective choice for best explanation, courtesy of Jerry Andrews, who wrote:

“The best choice (by a factor of 2) is to pick the OTHER bucket. When the pirate picks a bucket, he has a 1 in 3 chance o’ bein’ right, and a 2 in 3 chance o’ bein’ wrong. Now the captain knows which bucket bears the doubloon, so he’ll always lower a bucket with weevily bread—he’ll never choose the bucket with the doubloon, whether the pirate picked it not. Since the captain’s choice isn’t random, the odds that the pirate is wrong haven’t changed—they’re still 2 in 3. By changing his choice, he’s doubled his chance o’ bein’ right, and becomin’ captain himself. By stickin’ with his original choice, he [would’ve] proved he’s a regular pirate himself, and may not be bright enough to be captain. On the other hand, it’s usually better to be lucky than good, so maybe he’ll win the job anyway.”

I liked this answer because it was about as concise as possible, as well as being expressed in piratical patois.  Jerry, Jim, you are hereby awarded a genuine Rigger’s Apprentice T-shirt. Let me know your sizes and mailing addresses and we will get them shipped.

By the way, the first version of this puzzle was published by Joseph Bertrand in 1889, and people have been arguing about it ever since. It is best-known today as the Monty Hall Puzzle (hence the name of the pirate captain). There is a considerable body of commentary around the puzzle, with my favorite being that spurred by Marilyn Vos Savant’s version in Parade magazine, back in 1990. You can read one account of this here: http://www.stayorswitch.com/history.html.

The problem is that the correct answer is so deeply counterintuitive that most non-experts — and even many experts

— refuse to believe the answer, even when it has been carefully explained.

We’ll be posting a helm balance puzzle in a week, so be sure to check in. If you would like to be notified when we post a puzzle or article, you can subscribe at the bottom of this post, or any of my other posts.

 

Puzzle: The Pirate’s Dilemma

 

 

Captain Montgomery Hall, the famous pirate, was getting ready to retire, and wanted to be sure he had a qualified successor, so one morning he came on deck with three buckets, their tops covered. As the crew watched he hoisted each of them overhead on separate halyards.

“To be a captain,” he said, “Ye have to be smart. Who amongst ye is the smartest?”

The pirates conferred a bit, and then pushed forward their reluctant choice.

“All right, we’ll see how smart ye are. There’s a gold doubloon in one a’them buckets. There’s a piece of stale, weevily bread in the other two. Pick the right bucket, and you get the doubloon, and the command. Pick the wrong one, ye get yer usual breakfast.”

“But captain,” said the sailor, “No matter how smart I might be, I could only pick the right bucket by luck.”

“Just by sayin’ that, it shows that at least ye aren’t stupid. But pick one anyway.”

So the sailor chose one of the buckets, walked over to the pin its halyard was on, and prepared to cast off.

“Wait just a minute,” said the captain, “Let’s make this more interesting.” And he went over to one of the other pins, lowered one of the other buckets to deck, and removed its cover. Inside was a piece of stale, weevily bread.

“This means that the doubloon is either in the bucket ye chose, or in the third bucket,” said the captain. Could be either one, right?”

“Ye-e-ss,” said the sailor thoughtfully.

“I’ll let ye change your mind, if ye want,” said the captain.

After the sailor considered the matter for a while, he walked away from his first choice, and lowered the third bucket to deck.

So here is the puzzle: Was this the smart thing to do? By changing his mind, did the sailor improve his chances, or make them worse, or did they stay the same?

If you think you know the answer, send it to puzzle@briontoss.com. Give a reason for your choice. Even if your answer isn’t correct, your courage alone qualifies for a drawing for a Rigger’s Apprentice T-shirt. There will be a bonus prize for the best explanation of the correct answer. Entries must be submitted by noon, Pacific Time, January 22nd. We will announce the winners on January 24th.

 

January 5 blog puzzle picture

Reef Knot, Thief Knot, Granny Knot, Grief Knot

Last week we showed you two knots, but asked you to name four. That’s because knots are partly about topography, partly about where the ends are. A classic example is that the Sheet Bend and the Bowline are identical in terms of topography, but one is a loop, one is a bend, and if you don’t make that distinction, bad things can happen in terms of how the structure is loaded.

In this Puzzle, we started with the picture at the top of this post. The upper one looks like a Square Knot, but it could also be what is known as a Thief Knot, thus:

The upper knot is a Reef Knot (Square Knot). The lower one is a Thief Knot.

The structure is the same, but the ends are on the same side of the standing parts with the Reef Knot, and diagonally opposed for the Thief Knot. As dear Mr. Ashley tells its story, “There is a legend that sailors tie clothesbags, and bread bags with this knot, and that thieves always retie them with reef knots and so are inevitably detected. It is a pleasing story that should encourage honesty. However, if I have ever met this knot in practical use, I have neither recognized it nor paid penalty for my failure to do so.”

An even more obscure pair of knots are the two that share the structure of the lower knot at the top of this post. If you were to pull back on that picture, you would either get the Granny Knot or the Whatknot. Neither of these knots are to be recommended for general use, but Ashley notes that, with the ends arranged in one way, the Whatknot is the least secure bend in the world. Pull on the standing parts, and the knot just crawls out of the rope. But flip the ends past each other, and it miraculously becomes one of the most secure bends in the world. You can see details on this, as well as how to turn this phenomenon into a really mean knot prank, in the ABK, #2579. Here is what the two not-quite-twins look like:

The upper knot is a Granny Knot. The lower knot is a Whatknot (Grief Knot).

I will take this opportunity to note that the Whatknot’s bipolar behavior is only an extreme example of a common issue; many knots’ reliability is entirely dependent, not just on how they are tied, but how they are drawn up, and how their ends are disposed.

Of the entries that got two of the knots right, the winner is Allan Jaenecke, who wins his choice of any of our DVD’s.

No one guessed correctly on three of the possible answers, but from the pool of got-’em-all entries, the winner is John D. Rae who runs the Marlinespike Sailor’s Guild page on Facebook. I am particularly pleased that John’s name got picked, as it makes it easy for me to give his site a plug. Go there, join that group. Oh, and John also introduced me to a new name for the Whatknot: the Grief Knot. This is a portmanteau of “Grief” and “Granny.” Makes for a catchy couplet (see title).

As always, the winners are welcome to trade their prizes in on other items in our catalog. Also as always I encourage readers to submit candidates for future Puzzles. So far no one has…

Until now I’ve been tacking the Puzzle onto the end of each blog entry, but in future it will have its own space. Next Wednesday, watch for a particularly tough puzzle about the difficult choice made by a pirate with aspirations to captaincy.

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