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2) It serves as a shock absorber, helping to absorb the boat's movement due
to the wave action. you obviously do not understand the mathematics of catenaries. NOBODY chains a boat to a dock, or a rock on shore. It doesn't take much of a wind to pull chain tight enough to be considered zero point zero zero zero zero zero three seven three of a shocker absorber. |
"NOYB" wrote in message ... 1) It decreases the pulling angle on the anchor relative to the bottom, thus improving the the ability of the anchor to *bite* the bottom better. 2) It serves as a shock absorber, helping to absorb the boat's movement due to the wave action. 3) It provides abrasion resistance against sharp bottom structure. 4) It helps the anchor drop straight down, rather than "sailing" when there's a strong current. Good answer NOYB! What are you doing up here...spying for Jeb? |
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Two fold
To stop abrasion on the bottom In a good blow the added weight of the chain keeps the anchor pulling horizontally and therefore digs deeper as opposed to being pulled up at a 45' angle djb wrote: great question!! d "Ivan Yonge" wrote in message ble.rogers.com... My friend told me to use Anchor chain to attach between the anchor and the rope.. what is the reason? I was trying to search on Internet but couldn't find a good explanation. Can anyone tell me why please? thanks I.Y |
"JAXAshby" wrote in message ... 2) It serves as a shock absorber, helping to absorb the boat's movement due to the wave action. you obviously do not understand the mathematics of catenaries. NOBODY chains a boat to a dock, or a rock on shore. In a light wind, the chain is lying flat along the bottom. If a large wave came along, the boat would have to tug the chain off the bottom. You get a damping effect when you lift the chain from the bottom and remove the slack from the line. You go from a parabolic shape in the rope and rode, to a straight line shape. In order to do that, a lot of energy is expended. Thus, the rode as as a shock absorber. Get it? |
"Short Wave Sportfishing" wrote in message ... On 15 Sep 2004 12:26:41 GMT, (JAXAshby) wrote: 2) It serves as a shock absorber, helping to absorb the boat's movement due to the wave action. you obviously do not understand the mathematics of catenaries. Why don't you explain the math - perhaps we can all learn something. Please don't encourage the stupid. |
On Wed, 15 Sep 2004 16:35:39 GMT, "NOYB" wrote:
"Short Wave Sportfishing" wrote in message .. . On 15 Sep 2004 12:26:41 GMT, (JAXAshby) wrote: 2) It serves as a shock absorber, helping to absorb the boat's movement due to the wave action. you obviously do not understand the mathematics of catenaries. Why don't you explain the math - perhaps we can all learn something. Please don't encourage the stupid. Hey, I'm curious - about the math and all. I mean, like, it must be complicated right? After all, it involves physics and geometry and arithmetical ratios - stuff like that. I'd really like to know. :) Later, Tom |
labomba states:
-In a "good blow", the small amount of chain used in most chain and rode setups is not going to keep the rode at a shallower angle. - Bilge- I'm not a deck-ape, mind, but I've sure been on the forepeak enough during anchoring operations. You also have to consider how big a circle you're allotted, swinging around and fetching up against someone else's ship is considered bad form. Most Captains I've sailed with pay out however many shots required to radius their circle, and then have the bosun set the brake, then they back down slow astern to "set" the anchor. After the deckies set the devil's claw, the "hang" of the chain is checked regularly by the mate on watch. Especially after the Sea-Land Express dragged her anchor and grounded off Capetown last year. Cheers; Mutiny is a Management Tool Select Your Tattoo while Sober |
Subject: Why need anchor chain?
From: labomba states: -In a "good blow", the small amount of chain used in most chain and rode setups is not going to keep the rode at a shallower angle. - Bilge- I'm not a deck-ape, mind, but I've sure been on the forepeak enough during anchoring operations. You also have to consider how big a circle you're allotted, swinging around and fetching up against someone else's ship is considered bad form. What the heck does that have to do with my statement? Most Captains I've sailed with pay out however many shots required to radius their circle, and then have the bosun set the brake, then they back down slow astern to "set" the anchor. See above reply. After the deckies set the devil's claw, the "hang" of the chain is checked regularly by the mate on watch. We're talking chain AND line here. Not ALL chain. Especially after the Sea-Land Express dragged her anchor and grounded off Capetown last year. So, the 846 foot, 32,600gt Sealand Express was using line and chain at the time? Capt. Bill |
labomba asks:
-What the heck does that have to do with my statement?- Bilge- I'm essentially agreeing with you: -In a "good blow", the small amount of chain used in most chain and rode setups is not going to keep the rode at a shallower angle-labomba -We're talking chain AND line here. Not ALL chain.-labomba and -So, the 846 foot, 32,600gt Sealand Express was using line and chain at the time?- labomba Bilge- You know dang well that she wasn't, chum. The point is that even with 4 or 5 shots of chain along the bottom, AND a "set" danforth anchor, you still need to keep an eye on your angle. Yeesh...pardon me for supporting you. Have a day; Mutiny is a Management Tool Select Your Tattoo while Sober |
Subject: Why need anchor chain?
From: (Bilgeman) labomba asks: -What the heck does that have to do with my statement?- Bilge- I'm essentially agreeing with you: -In a "good blow", the small amount of chain used in most chain and rode setups is not going to keep the rode at a shallower angle-labomba -We're talking chain AND line here. Not ALL chain.-labomba and -So, the 846 foot, 32,600gt Sealand Express was using line and chain at the time?- labomba Bilge- You know dang well that she wasn't, chum. The point is that even with 4 or 5 shots of chain along the bottom, AND a "set" danforth anchor, you still need to keep an eye on your angle. Yeesh...pardon me for supporting you. Have a day; Sorry if I misunderstood. I think it started when you started your reply with Bilge -. I though you were using it as a replacement for calling BS. And then when you went on talking about a large ship and swinging areas I lost the tie in. Capt. Bill |
labomba 'splains:
-Sorry if I misunderstood. I think it started when you started your reply with Bilge -.I though you were using it as a replacement for calling BS. And then when you went on talking about a large ship and swinging areas I lost the tie in.- Bilge---my shorthand nickname, (although many,many,many people will agree that it also means BS!). No problemo, Captain. Diego Garcia and Saipan are prime places to observe the imporatnce of staying in the little circle on the charts. Once the tide was running into Diego lagoon, and the American Cormorant was swinging, and we on the Gibson weren't...interesting watching "Big Red" come at you at such a stately pace. The unwritten backstory behind the Express' grounding is that they don't like to anchor close in, because the charterer, Maersk Line, supposedly doesn't like paying for launch service, and Capetown is one of the few ports in the container trade where you actually ride the hook while awaiting a berth...potential off time. I was on SeaLand Voyager last year, did 112 days and had 4 hours off the ship in Durban. And the corporate dummies wonder why no-one wants any past of their crappy industry! Personally, I think someone makes extra compensation for "cutting budget", that Maersk would pay launch service fees...but that's another story. In light of this, they try to anchor as far out as possible, and this being South Africa right off the Southern Ocean, they anchored maybe a little further out than was...prudent. Word around the hall is they were dragging anchor and heading for the island prison where Mandella was kept for all those years under Apartheid. Much opportunity for "pucker factor". Regards; Mutiny is a Management Tool Select Your Tattoo while Sober |
Diego Garcia and Saipan are prime places to observe the imporatnce of staying
in the little circle on the charts. of course. far and away the most important anchorages for cruisers in the entire world. btw, what does the US Navy say about anchoring around Diego Garcia? |
jaxahby asks:
-of course. far and away the most important anchorages for cruisers in the entire world. btw, what does the US Navy say about anchoring around Diego Garcia?- Bilge- Not that the US Navy has any say in the matter, (nudge-nudge, wink-wink), since it's British Territory, and you know how the Limeys can be...very clubby. "By invitation ONLY, old chap". In fact, they have had quite a fleet of seized fishing boats that they occassionally tow out and "request" that the US forces "assist" them in machine-gunning to the bottom...always an occasion for an island-wide picnic...a big draw. Hey, everyone gets bored. What in the heck would you want to go to "Dodge" for, anyway? Are you queer for sea turtles and coconut crabs? See Diego the civilized way...I pulled some strings for you...I have "friends"...check the link: http://www.zianet.com/tedmorris/dg/links.html#this Trust me, this is much better, less AA meetings to attend. Cheers; Mutiny is a Management Tool Select Your Tattoo while Sober |
Diego Garcia, according to widespread reports, is leased to the US Navy. You
heard different? I understand the indigents removed to Mosambique (?) are still ****ed even after several decades. Perhaps you can enlighten us? nah, you are a dum squat. From: (Bilgeman) Date: 9/17/2004 1:43 AM Eastern Daylight Time Message-id: jaxahby asks: -of course. far and away the most important anchorages for cruisers in the entire world. btw, what does the US Navy say about anchoring around Diego Garcia?- Bilge- Not that the US Navy has any say in the matter, (nudge-nudge, wink-wink), since it's British Territory, and you know how the Limeys can be...very clubby. "By invitation ONLY, old chap". In fact, they have had quite a fleet of seized fishing boats that they occassionally tow out and "request" that the US forces "assist" them in machine-gunning to the bottom...always an occasion for an island-wide picnic...a big draw. Hey, everyone gets bored. What in the heck would you want to go to "Dodge" for, anyway? Are you queer for sea turtles and coconut crabs? See Diego the civilized way...I pulled some strings for you...I have "friends"...check the link: http://www.zianet.com/tedmorris/dg/links.html#this Trust me, this is much better, less AA meetings to attend. Cheers; Mutiny is a Management Tool Select Your Tattoo while Sober |
gene, you are one gullible sob. ever understand a single thing you read?
nah. go read The Daily Worker for insights in social economics, but for sure stay out of any discussions of anchors. From: "Gene Kearns" **** dumb squat**** Date: 9/17/2004 8:38 AM Eastern Daylight Time Message-id: On 15 Sep 2004 12:23:55 GMT, (JAXAshby) wrote: 1) It decreases the pulling angle on the anchor relative to the bottom, thus improving the the ability of the anchor to *bite* the bottom better. not really, except under lite wind conditions. Then it is true. I guess current and tide are different, somehow. I suppose the anchor and rode, somehow, just *know* the difference. "Lite" is ambiguous and not very useful. Moving from an all line rode to a chain rode (as shown in the accompanying URL) can increase the usable rode tension by a factor of 8. http://www.johnsboatstuff.com/Articles/anchor.htm -- Grady-White Gulfstream, out of Southport, NC. http://myworkshop.idleplay.net/cavern/ Homepage http://www.southharbourvillageinn.com/directions.asp Where Southport,NC is located. http://www.southharbourvillageinn.linksysnet.com Real Time Pictures at My Marina http://www.thebayguide.com/rec.boats Rec.boats at Lee Yeaton's Bayguide |
genie, knock it off. you are a mechanic on twenty year aircraft engines of
seventy year old engine designs. what you know about catenaries wouldn't fill a plastic coffee stirrer spoon from Mickey D's. ***dum squat*** "Gene Kearns" Date: 9/17/2004 9:49 AM Eastern Daylight Time Message-id: On 15 Sep 2004 12:26:41 GMT, (JAXAshby) wrote: 2) It serves as a shock absorber, helping to absorb the boat's movement due to the wave action. you obviously do not understand the mathematics of catenaries. NOBODY chains a boat to a dock, or a rock on shore. Nobody needs the properties of a catenary at a dock, either. Nobody makes a big deal about creating a catenary, when tying to a dock. Nobody in their right mind would even mention such a stupid and unrelated concept, if they were trying to make a logical argument. It doesn't take much of a wind to pull chain tight enough to be considered zero point zero zero zero zero zero three seven three of a shocker absorber. Stoopid, stoopid, stoopid. The intrinsic shape of a catenary is the shock absorber. Once the shape of the catenary has been pulled tight enough for the resultant to become a line, all holding power is pretty much lost, as the vertical component on the anchor increases. At that point, by definition, we aren't talking about catenaries, anyway. So, which is easier to pull tight, a line catenary or a chain catenary? Here is a URL that will conclusively... and mathematically, prove that Jax doesn't have a clue what he is talking about..... and, moreover, that he is just plain wrong (again). This website includes a snappy macro driven spread sheet that will work out nearly any what-if you could ever imagine concerning line, chain, scope, tension, etc., etc., etc. It really *is* neat.... http://alain.fraysse.free.fr/sail/ro...ic/sta_hom.htm -- Grady-White Gulfstream, out of Southport, NC. http://myworkshop.idleplay.net/cavern/ Homepage http://www.southharbourvillageinn.com/directions.asp Where Southport,NC is located. http://www.southharbourvillageinn.linksysnet.com Real Time Pictures at My Marina http://www.thebayguide.com/rec.boats Rec.boats at Lee Yeaton's Bayguide |
whoring, you done be had. hope you enjoyed it, even if you do walk a little
for a few days. From: JohnH Date: 9/17/2004 1:06 PM Eastern Daylight Time Message-id: On Fri, 17 Sep 2004 09:49:10 -0400, "Gene Kearns" wrote: On 15 Sep 2004 12:26:41 GMT, (JAXAshby) wrote: 2) It serves as a shock absorber, helping to absorb the boat's movement due to the wave action. you obviously do not understand the mathematics of catenaries. NOBODY chains a boat to a dock, or a rock on shore. Nobody needs the properties of a catenary at a dock, either. Nobody makes a big deal about creating a catenary, when tying to a dock. Nobody in their right mind would even mention such a stupid and unrelated concept, if they were trying to make a logical argument. It doesn't take much of a wind to pull chain tight enough to be considered zero point zero zero zero zero zero three seven three of a shocker absorber. Stoopid, stoopid, stoopid. The intrinsic shape of a catenary is the shock absorber. Once the shape of the catenary has been pulled tight enough for the resultant to become a line, all holding power is pretty much lost, as the vertical component on the anchor increases. At that point, by definition, we aren't talking about catenaries, anyway. So, which is easier to pull tight, a line catenary or a chain catenary? Here is a URL that will conclusively... and mathematically, prove that Jax doesn't have a clue what he is talking about..... and, moreover, that he is just plain wrong (again). This website includes a snappy macro driven spread sheet that will work out nearly any what-if you could ever imagine concerning line, chain, scope, tension, etc., etc., etc. It really *is* neat.... http://alain.fraysse.free.fr/sail/ro...ic/sta_hom.htm Wow. Great site. Thanks. John H On the 'Poco Loco' out of Deale, MD, on the beautiful Chesapeake Bay! |
JohnH wrote:
Jax, for what it's worth, I value your opinion about as much as that of Krause. John H Indeed, Herring, your head is so full of right-wing, militaristic crap, there's no room left for knowledge or wisdom, no matter the source. I pity the poor souls who are entrusted to you in the classes where you substitute. -- Not dead, in jail, or a slave? Thank a liberal! And don't forget to pay your taxes so the rich don't have to! |
whoring, for what it is worth, you couldn't tell the difference.
Date: 9/18/2004 9:18 AM Eastern Daylight Time Message-id: On 18 Sep 2004 03:43:41 GMT, (JAXAshby) wrote: whoring, you done be had. hope you enjoyed it, even if you do walk a little for a few days. From: JohnH Date: 9/17/2004 1:06 PM Eastern Daylight Time Message-id: On Fri, 17 Sep 2004 09:49:10 -0400, "Gene Kearns" wrote: On 15 Sep 2004 12:26:41 GMT, (JAXAshby) wrote: 2) It serves as a shock absorber, helping to absorb the boat's movement due to the wave action. you obviously do not understand the mathematics of catenaries. NOBODY chains a boat to a dock, or a rock on shore. Nobody needs the properties of a catenary at a dock, either. Nobody makes a big deal about creating a catenary, when tying to a dock. Nobody in their right mind would even mention such a stupid and unrelated concept, if they were trying to make a logical argument. It doesn't take much of a wind to pull chain tight enough to be considered zero point zero zero zero zero zero three seven three of a shocker absorber. Stoopid, stoopid, stoopid. The intrinsic shape of a catenary is the shock absorber. Once the shape of the catenary has been pulled tight enough for the resultant to become a line, all holding power is pretty much lost, as the vertical component on the anchor increases. At that point, by definition, we aren't talking about catenaries, anyway. So, which is easier to pull tight, a line catenary or a chain catenary? Here is a URL that will conclusively... and mathematically, prove that Jax doesn't have a clue what he is talking about..... and, moreover, that he is just plain wrong (again). This website includes a snappy macro driven spread sheet that will work out nearly any what-if you could ever imagine concerning line, chain, scope, tension, etc., etc., etc. It really *is* neat.... http://alain.fraysse.free.fr/sail/ro...ic/sta_hom.htm Wow. Great site. Thanks. John H On the 'Poco Loco' out of Deale, MD, on the beautiful Chesapeake Bay! Jax, for what it's worth, I value your opinion about as much as that of Krause. John H On the 'Poco Loco' out of Deale, MD, on the beautiful Chesapeake Bay! |
JAXAshby wrote:
whoring, for what it is worth, you couldn't tell the difference. Oohhh... John Whoring. Great! You don't mind if I borrow that one, eh? -- Not dead, in jail, or a slave? Thank a liberal! And don't forget to pay your taxes so the rich don't have to! |
Gould 0738 wrote:
JAXAshby wrote: whoring, for what it is worth, you couldn't tell the difference. Oohhh... John Whoring. Great! You don't mind if I borrow that one, eh? The only thing worse than Jaxashby running out of meds and mounting his keyboard for a day or two has to be Jaxashby runing out of meds, mounting his keyboard, and you encouraging him, Harry. Hey! Jax doesn't often come up with anything worthwhile...but that "nick" for Herringbrain is a keeper. -- Not dead, in jail, or a slave? Thank a liberal! And don't forget to pay your taxes so the rich don't have to! |
Chuck, Maybe we need more anchor chain to keep both bodies down.
"Gould 0738" wrote in message ... JAXAshby wrote: whoring, for what it is worth, you couldn't tell the difference. Oohhh... John Whoring. Great! You don't mind if I borrow that one, eh? The only thing worse than Jaxashby running out of meds and mounting his keyboard for a day or two has to be Jaxashby runing out of meds, mounting his keyboard, and you encouraging him, Harry. |
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spell it any way you want, you still do not have any idea what it is.
yo-yo, a string strung between two points has, and always has, a catenary. go look it up. Gene Kearns Date: 9/18/2004 2:03 PM Eastern Daylight Time Message-id: On 18 Sep 2004 03:42:02 GMT, (JAXAshby) wrote: genie, knock it off. you are a mechanic on twenty year aircraft engines of seventy year old engine designs. what you know about catenaries wouldn't fill a plastic coffee stirrer spoon from Mickey D's. I don't know about that.... at least I have taught you to *spell* the word correctly... you haven't spelled "caternary" once. That's nice. Actually is seems to indicate that you can be trained... at some level. I still haven't made any progress in teaching you the math and physics of the function, though. I don't feel bad, though, you never learned it during all those years of high school, either... Now, take your crayons and try to draw, to your own satisfaction of course, how one uses catenaries to make fast to the dock. If you want to make construction paper cutouts to help, do let mommy or daddy in the white coat get the round pointed scissors, ok? -- Grady-White Gulfstream, out of Southport, NC. http://myworkshop.idleplay.net/cavern/ Homepage http://www.southharbourvillageinn.com/directions.asp Where Southport,NC is located. http://www.thebayguide.com/rec.boats Rec.boats at Lee Yeaton's Bayguide |
genie, knock it off. you are a mechanic on twenty year aircraft engines of
seventy year old engine designs. what you know about catenaries wouldn't fill a plastic coffee stirrer spoon from Mickey D's. I'm still appreciate you explaining the mathematics of catenaries. here is a utterly simple book for you (it is $48). I was looking for one a little more engineering oriented, but still quite simple and only goes in the special case of oil rig anchors ($1,015, plus shipping and handling), but I can't remember the exact title. (I don't have it in my personal library) What happens during the interaction of forces on the rode would be most fascinating. Later, Tom |
What happens during the interaction of forces on the rode would be
most fascinating. a way to simplified look at it is to consider the chain/rode/line to have zero weight pulled between two points (say 100 feet apart), then hang a 1# weight in the center point and check how much strain it put on the end points when the weight hangs 20 feet, then 10 feet, then 5 feet, then 1 foot, then 1 inch, then 1/10th inch. Just use trig to figure the forces. the forces get out of hand ********VERY******** quickly. Even worse, is that the weight in the middle (or chain) has momentum as the boat rocks, so the "natural" position of the weight overshoots and makes for seriously high g-loads. |
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a way to simplified look at it is to consider the chain/rode/line to have
zero weight pulled between two points (say 100 feet apart), then hang a 1# weight in the center point and check how much strain it put on the end points when the weight hangs 20 feet, then 10 feet, then 5 feet, then 1 foot, then 1 inch, then 1/10th inch. Just use trig to figure the forces. So what would the forces be using your example? I don't have a trig calc handy, but do this. divide 50 feet by 20 feet, then 10 feet, then 5 feet, then 1 foot, then 1 inch, then 1/10th inch. that will give you the tangent of each angle. look up each tangent, then divide each number into 1#. that will give you the #'s force on the end points of the line. a catenary is worse and much, much, much more difficult to calculate, but the above will give you an idea of the HUGE forces involved once the chain starts to pull tight Later, Tom |
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On Sat, 18 Sep 2004 19:46:04 -0400, Gene Kearns
wrote: On 18 Sep 2004 21:15:33 GMT, (JAXAshby) wrote: What happens during the interaction of forces on the rode would be most fascinating. a way to simplified look at it is to consider the chain/rode/line to have zero weight pulled between two points (say 100 feet apart), then hang a 1# weight in the center point and check how much strain it put on the end points when the weight hangs 20 feet, then 10 feet, then 5 feet, then 1 foot, then 1 inch, then 1/10th inch. Just use trig to figure the forces. So.... we just used intuitive trig to figure out why (1) we use scope with an anchor and (2) why we don't tie boats to the dock with chain. Now *that* is some real science...... And your "simplified look" does not apply.... an anchor rode does not employ both ends at the same "Y" value.... therefore assumptions of Y=Y'=0 do not obtain and is, therefore, the root cause of your lack of understanding in this area. There isn't *anything* *attached* to the middle. But wouldn't the strain be equal at the arthimetical center and can be equated to weight? It's really just another to figure energy transfer, right? I'm not totaly familiar with this so if I mess this up, it's an electronic engineer with a math degree playing at mechanics, but catenary defined means the shape of the line (or in this case rode) as a curve. A funciton of strain would be weights at either end. Strain can be defined as stored energy which is, I would think, distributed evenly along the line to the end points. One way to define how much strain is being applied would be to add weight to the middle and measure the deflection. At that point, it becomes a trig function - yes/no? the forces get out of hand ********VERY******** quickly. Even worse, is that the weight in the middle (or chain) has momentum as the boat rocks, so the "natural" position of the weight overshoots and makes for seriously high g-loads. There is no weight "in the middle" (other than the weight of the rode) .... so you put two anchors on the same rode? Odd. Using that concept, most people use kellets and think it is a good and useful idea. What's a kellet? Later, Tom |
"Gene Kearns" wrote in message ... On 18 Sep 2004 21:15:33 GMT, (JAXAshby) wrote: What happens during the interaction of forces on the rode would be most fascinating. a way to simplified look at it is to consider the chain/rode/line to have zero weight pulled between two points (say 100 feet apart), then hang a 1# weight in the center point and check how much strain it put on the end points when the weight hangs 20 feet, then 10 feet, then 5 feet, then 1 foot, then 1 inch, then 1/10th inch. Just use trig to figure the forces. So.... we just used intuitive trig to figure out why (1) we use scope with an anchor and (2) why we don't tie boats to the dock with chain. Now *that* is some real science...... And your "simplified look" does not apply.... an anchor rode does not employ both ends at the same "Y" value.... therefore assumptions of Y=Y'=0 do not obtain and is, therefore, the root cause of your lack of understanding in this area. There isn't *anything* *attached* to the middle. the forces get out of hand ********VERY******** quickly. Even worse, is that the weight in the middle (or chain) has momentum as the boat rocks, so the "natural" position of the weight overshoots and makes for seriously high g-loads. There is no weight "in the middle" (other than the weight of the rode) .... so you put two anchors on the same rode? Odd. Also, in jaxassby's example, the points can't always be 100' apart if the weight is hanging further and further down each time...unless he has an extremely elastic line and there's a large amount of stretch. I assume that jaxassby meant to say "using a 100' rope". |
On Sat, 18 Sep 2004 20:14:34 -0400, "NOYB" wrote:
"Gene Kearns" wrote in message .. . On 18 Sep 2004 21:15:33 GMT, (JAXAshby) wrote: What happens during the interaction of forces on the rode would be most fascinating. a way to simplified look at it is to consider the chain/rode/line to have zero weight pulled between two points (say 100 feet apart), then hang a 1# weight in the center point and check how much strain it put on the end points when the weight hangs 20 feet, then 10 feet, then 5 feet, then 1 foot, then 1 inch, then 1/10th inch. Just use trig to figure the forces. So.... we just used intuitive trig to figure out why (1) we use scope with an anchor and (2) why we don't tie boats to the dock with chain. Now *that* is some real science...... And your "simplified look" does not apply.... an anchor rode does not employ both ends at the same "Y" value.... therefore assumptions of Y=Y'=0 do not obtain and is, therefore, the root cause of your lack of understanding in this area. There isn't *anything* *attached* to the middle. the forces get out of hand ********VERY******** quickly. Even worse, is that the weight in the middle (or chain) has momentum as the boat rocks, so the "natural" position of the weight overshoots and makes for seriously high g-loads. There is no weight "in the middle" (other than the weight of the rode) .... so you put two anchors on the same rode? Odd. Also, in jaxassby's example, the points can't always be 100' apart if the weight is hanging further and further down each time...unless he has an extremely elastic line and there's a large amount of stretch. I assume that jaxassby meant to say "using a 100' rope". The main definition of catenary is that of a curve formed by a perfectly flexible, uniformly dense, and inextensible cable suspended from its endpoints. It would look a lot like hyperbolic cosine if you graphed it out. Which, now that I think about it, wouldn't look a lot like an anchor rode as much as a tow line. I'm more curious about strain towards the middle of the curve. That would be fairly easy to measure at either end, but if you have two opposing forces of two different weights, say as in a barge tow, the center strain would constantly move towards one or the other depending on the weights. How would you determine that mathematically? Later, Tom |
whoring, once you lose sight of a trick, you lose sight of anthing real.
try again, this time without anything in your mouth. From: JohnH Date: 9/18/2004 8:34 PM Eastern Daylight Time Message-id: On 18 Sep 2004 23:14:45 GMT, (JAXAshby) wrote: a way to simplified look at it is to consider the chain/rode/line to have zero weight pulled between two points (say 100 feet apart), then hang a 1# weight in the center point and check how much strain it put on the end points when the weight hangs 20 feet, then 10 feet, then 5 feet, then 1 foot, then 1 inch, then 1/10th inch. Just use trig to figure the forces. So what would the forces be using your example? I don't have a trig calc handy, but do this. divide 50 feet by 20 feet, then 10 feet, then 5 feet, then 1 foot, then 1 inch, then 1/10th inch. that will give you the tangent of each angle. look up each tangent, then divide each number into 1#. that will give you the #'s force on the end points of the line. a catenary is worse and much, much, much more difficult to calculate, but the above will give you an idea of the HUGE forces involved once the chain starts to pull tight 50/20=2.5 50/10=5 50/5=10 50/1=50 50/1/12=600 50/1/120=6000 If each of these are divided into 1, the results would be, respectively: 0.4 0.2 0.1 0.02 0.001666... 0.0001666... These numbers don't look so big. Could you have made an error? John H On the 'Poco Loco' out of Deale, MD, on the beautiful Chesapeake Bay! |
clown, check the meaning of the word.
Gene Kearns Date: 9/18/2004 7:22 PM Eastern Daylight Time Message-id: On 18 Sep 2004 20:49:57 GMT, (JAXAshby) wrote: spell it any way you want, you still do not have any idea what it is. yo-yo, a string strung between two points has, and always has, a catenary. go look it up. And a yo-yo is about the depth of your comprehension, here.... -- Grady-White Gulfstream, out of Southport, NC. http://myworkshop.idleplay.net/cavern/ Homepage http://www.southharbourvillageinn.com/directions.asp Where Southport,NC is located. http://www.thebayguide.com/rec.boats Rec.boats at Lee Yeaton's Bayguide |
genie, shut up.
Subject: Why need anchor chain? From: Gene Kearns Date: 9/18/2004 7:46 PM Eastern Daylight Time Message-id: On 18 Sep 2004 21:15:33 GMT, (JAXAshby) wrote: What happens during the interaction of forces on the rode would be most fascinating. a way to simplified look at it is to consider the chain/rode/line to have zero weight pulled between two points (say 100 feet apart), then hang a 1# weight in the center point and check how much strain it put on the end points when the weight hangs 20 feet, then 10 feet, then 5 feet, then 1 foot, then 1 inch, then 1/10th inch. Just use trig to figure the forces. So.... we just used intuitive trig to figure out why (1) we use scope with an anchor and (2) why we don't tie boats to the dock with chain. Now *that* is some real science...... And your "simplified look" does not apply.... an anchor rode does not employ both ends at the same "Y" value.... therefore assumptions of Y=Y'=0 do not obtain and is, therefore, the root cause of your lack of understanding in this area. There isn't *anything* *attached* to the middle. the forces get out of hand ********VERY******** quickly. Even worse, is that the weight in the middle (or chain) has momentum as the boat rocks, so the "natural" position of the weight overshoots and makes for seriously high g-loads. There is no weight "in the middle" (other than the weight of the rode) .... so you put two anchors on the same rode? Odd. Using that concept, most people use kellets and think it is a good and useful idea. -- Grady-White Gulfstream, out of Southport, NC. http://myworkshop.idleplay.net/cavern/ Homepage http://www.southharbourvillageinn.com/directions.asp Where Southport,NC is located. http://www.thebayguide.com/rec.boats Rec.boats at Lee Yeaton's Bayguide |
"Short Wave Sportfishing" wrote in message ... On Sat, 18 Sep 2004 19:46:04 -0400, Gene Kearns wrote: On 18 Sep 2004 21:15:33 GMT, (JAXAshby) wrote: What happens during the interaction of forces on the rode would be most fascinating. a way to simplified look at it is to consider the chain/rode/line to have zero weight pulled between two points (say 100 feet apart), then hang a 1# weight in the center point and check how much strain it put on the end points when the weight hangs 20 feet, then 10 feet, then 5 feet, then 1 foot, then 1 inch, then 1/10th inch. Just use trig to figure the forces. So.... we just used intuitive trig to figure out why (1) we use scope with an anchor and (2) why we don't tie boats to the dock with chain. Now *that* is some real science...... And your "simplified look" does not apply.... an anchor rode does not employ both ends at the same "Y" value.... therefore assumptions of Y=Y'=0 do not obtain and is, therefore, the root cause of your lack of understanding in this area. There isn't *anything* *attached* to the middle. But wouldn't the strain be equal at the arthimetical center and can be equated to weight? It's really just another to figure energy transfer, right? I'm not totaly familiar with this so if I mess this up, it's an electronic engineer with a math degree playing at mechanics, but catenary defined means the shape of the line (or in this case rode) as a curve. A funciton of strain would be weights at either end. Strain can be defined as stored energy which is, I would think, distributed evenly along the line to the end points. One way to define how much strain is being applied would be to add weight to the middle and measure the deflection. At that point, it becomes a trig function - yes/no? Yes, assuming the line itself has negligible mass compared to the weight pulling on it...which is not a practical assumption when comparing it to an anchor line and chain rode. I don't know why jackassby even used this example. Jackassby's example describes a straight line...not a catenary. It is not even close to replicating what is happening to an anchor line and chain rode. The only time that Jax's example *may* similate an anchor line is when the force of the wind is so great that the line and chain is perfectly straight...which *never* happens in a real world situation anyhow. If the wind pulled so hard that the line was perfectly straight, it wouldn't be a catenary any longer...it would be a straight line. And if it were a straight line, the vertical component of force exerted by the boat on the anchor would be so high that the anchor would pull loose. Go look at the website Gene posted: http://alain.fraysse.free.fr/sail/ro...ic/sta_hom.htm It explains it all. |
"JAXAshby" wrote in message ... genie, shut up. Subject: Why need anchor chain? From: Gene Kearns Date: 9/18/2004 7:46 PM Eastern Daylight Time Message-id: On 18 Sep 2004 21:15:33 GMT, (JAXAshby) wrote: What happens during the interaction of forces on the rode would be most fascinating. a way to simplified look at it is to consider the chain/rode/line to have zero weight pulled between two points (say 100 feet apart), then hang a 1# weight in the center point and check how much strain it put on the end points when the weight hangs 20 feet, then 10 feet, then 5 feet, then 1 foot, then 1 inch, then 1/10th inch. Just use trig to figure the forces. So.... we just used intuitive trig to figure out why (1) we use scope with an anchor and (2) why we don't tie boats to the dock with chain. Now *that* is some real science...... And your "simplified look" does not apply.... an anchor rode does not employ both ends at the same "Y" value.... therefore assumptions of Y=Y'=0 do not obtain and is, therefore, the root cause of your lack of understanding in this area. There isn't *anything* *attached* to the middle. the forces get out of hand ********VERY******** quickly. Even worse, is that the weight in the middle (or chain) has momentum as the boat rocks, so the "natural" position of the weight overshoots and makes for seriously high g-loads. There is no weight "in the middle" (other than the weight of the rode) .... so you put two anchors on the same rode? Odd. Using that concept, most people use kellets and think it is a good and useful idea. http://www.johnsboatstuff.com/Articles/anchor.htm " Having a lot of sag in the rode reduces shock loads " Isn't that what started this whole argument? Anchor chain introduces sag in the rode. Sag in the rode reduces shock loads. So I guess I was right when I said that anchor chain acts as a shock absorber, eh jaxie? |
"Short Wave Sportfishing" wrote in message ... On Sat, 18 Sep 2004 20:14:34 -0400, "NOYB" wrote: "Gene Kearns" wrote in message .. . On 18 Sep 2004 21:15:33 GMT, (JAXAshby) wrote: What happens during the interaction of forces on the rode would be most fascinating. a way to simplified look at it is to consider the chain/rode/line to have zero weight pulled between two points (say 100 feet apart), then hang a 1# weight in the center point and check how much strain it put on the end points when the weight hangs 20 feet, then 10 feet, then 5 feet, then 1 foot, then 1 inch, then 1/10th inch. Just use trig to figure the forces. So.... we just used intuitive trig to figure out why (1) we use scope with an anchor and (2) why we don't tie boats to the dock with chain. Now *that* is some real science...... And your "simplified look" does not apply.... an anchor rode does not employ both ends at the same "Y" value.... therefore assumptions of Y=Y'=0 do not obtain and is, therefore, the root cause of your lack of understanding in this area. There isn't *anything* *attached* to the middle. the forces get out of hand ********VERY******** quickly. Even worse, is that the weight in the middle (or chain) has momentum as the boat rocks, so the "natural" position of the weight overshoots and makes for seriously high g-loads. There is no weight "in the middle" (other than the weight of the rode) .... so you put two anchors on the same rode? Odd. Also, in jaxassby's example, the points can't always be 100' apart if the weight is hanging further and further down each time...unless he has an extremely elastic line and there's a large amount of stretch. I assume that jaxassby meant to say "using a 100' rope". The main definition of catenary is that of a curve formed by a perfectly flexible, uniformly dense, and inextensible cable suspended from its endpoints. It would look a lot like hyperbolic cosine if you graphed it out. Which, now that I think about it, wouldn't look a lot like an anchor rode as much as a tow line. I'm more curious about strain towards the middle of the curve. That would be fairly easy to measure at either end, but if you have two opposing forces of two different weights, say as in a barge tow, the center strain would constantly move towards one or the other depending on the weights. How would you determine that mathematically? Later, Tom The end points are not at the same elevation. |
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