| View previous topic :: View next topic |
| Author |
Message |
nw30
Joined: 21 Dec 2008
Posts: 6485
Location: The eye of the universe, Cen. Cal. coast
|
 Posted: Wed Oct 05, 2016 12:45 pm Post subject: |
 |
|
Boy, after skimming thru this thread, I'm really glad I don't use harness lines.  |
|
| Back to top |
|
 |
isobars
Joined: 12 Dec 1999
Posts: 20935
|
| Posted: Wed Oct 05, 2016 5:38 pm Post subject: |
|
|
Ittiandro, as an engineer with a strong emphasis on physics, I see many misconceptions in your posts about fulcrums, levers, etc as applied to WSing. I'm sorry that I don't have time to elaborate on them, but here are a few points.
• Until and unless you correct your basic misconceptions about where the fulcrums and levers are in WSing, physics will only confuse you. Fugheddabout the mast and focus instead on the distribution of forces in your hands. The further away your reactive forces are from the COE, the harder your muscles have to work.
• Although Guy Cribb is a great resource, he is not infallible. But even then I doubt he said to move our hands forward or aft to gain leverage over the mast. The boom is not a pry bar or lever and the mast is neither a fulcrum nor a lever in this context.
• Swchandler knows and usually covers windsurfing topics very well and very clearly; don't blow him off for that reason. Here's my understanding of your quote of him (Swchandler resentfully said “ Guy Cribb? Why don't you just do what he says then? Why listen to me? Problem solved, right?”): If he's resentful, it's due to your historical and present resistance to our answers to your questions. Beaglebuddy summed it up pretty well.
• Debate and explanation is neither "sparring" nor "belligerence" among adults. It's just debate, and if kept impersonal can contribute a great deal of information and options to readers.
• Where would your two hands grasp a 200-pound, 6-foot-long beam to lift it ... spanning its center of gravity or off-center towards one end?
Last edited by isobars on Thu Oct 06, 2016 3:32 pm; edited 1 time in total |
|
| Back to top |
|
|
windoggi
Joined: 22 Feb 2002
Posts: 2743
|
| Posted: Wed Oct 05, 2016 7:32 pm Post subject: |
|
|
ISO ❤️S SWCHANDLER
_________________
/w\ |
|
| Back to top |
|
|
techno900
Joined: 28 Mar 2001
Posts: 4161
|
| Posted: Fri Oct 07, 2016 7:53 am Post subject: |
|
|
You have a weight lifting barbell at your feet, a 10lb weight on the left and 20lb weight on your right (this is your boom/sail).
Clearly, the COE is not in the center but a little to the right. Guess where that point is, then spread your hands equal distance (about 12") from that estimated COE, and lift.
If there is more weight on the right hand, shuffle your hands to the right. If there is more weight on the left hand, shuffle your hands to the left. When balanced, that's where you attach your harness lines.
Only logic is needed to solve the problem, physics to understand it.
Then realize that it will be different for every sail, plus COE will change as the wind lulls and gusts, we just hope we find the average. |
|
| Back to top |
|
|
konajoe
Joined: 28 Feb 2010
Posts: 517
|
| Posted: Fri Oct 07, 2016 11:02 am Post subject: |
|
|
Hi Ittiandro! Techno nailed it.
| techno900 wrote: | You have a weight lifting barbell at your feet, a 10lb weight on the left and 20lb weight on your right (this is your boom/sail).
Clearly, the COE is not in the center but a little to the right. Guess where that point is, then spread your hands equal distance (about 12") from that estimated COE, and lift.
If there is more weight on the right hand, shuffle your hands to the right. If there is more weight on the left hand, shuffle your hands to the left. When balanced, that's where you attach your harness lines.
Only logic is needed to solve the problem, physics to understand it.
Then realize that it will be different for every sail, plus COE will change as the wind lulls and gusts, we just hope we find the average. |
Read this carefully. Draw a line from the mast end of the boom to the back end of the boom. The sail is generating lift perpendicular to this line. That's your barbell.
Drop the lever concept. Adopt the barbell concept.
I feel that the fact that you sailed a long time without a harness will help you in the long run. The 2 harness line connection points are substitutes for your hands. So, move the connection points as you would move your hands. If you have too much load on your back hand, move either one or both hands back. You've been doing it all along. Move your harness line connection points so that they are symmetrically placed between your hands.
Too much front hand load? Do the opposite. |
|
| Back to top |
|
|
ittiandro
Joined: 22 Nov 2009
Posts: 294
|
| Posted: Wed Oct 19, 2016 8:58 am Post subject: |
|
|
| isobars wrote: | Ittiandro, as an engineer with a strong emphasis on physics, I see many misconceptions in your posts about fulcrums, levers, etc as applied to WSing. I'm sorry that I don't have time to elaborate on them, but here are a few points.
• Until and unless you correct your basic misconceptions about where the fulcrums and levers are in WSing, physics will only confuse you...The further away your reactive forces are from the COE, the harder your muscles have to work.
• Swchandler knows and usually covers windsurfing topics very well and very clearly; don't blow him off for that reason. Here's my understanding of your quote of him (Swchandler resentfully said “ Guy Cribb? Why don't you just do what he says then? Why listen to me? Problem solved, right?”): If he's resentful, it's due to your historical and present resistance to our answers to your questions.
• Debate and explanation is neither "sparring" nor "belligerence" among adults. It's just debate, and if kept impersonal can contribute a great deal of information and options to readers.
|
I think we should really put this issue to rest, as you suggest, because to further pursue it from my original perspective would necessitate both of us venturing more deeply into physics, which is beyond the scope of a windsurfing forum, of no interest to most windsurfers and probably beyond the understanding of the average person, including myself (even though the physics of the lever are simple enough to be understood by any high-school graduate without having recourse to..Riemann’s geometry).
Before putting this issue to rest, though, I’ll only comment briefly on your remarks about my misconceptions and your idea that I have a” historic resistance” to the answers given by various members on this issue.
I may have misconceptions on the physics underlying these issues and you probably have, as an engineer, a better understanding than me..
What you call my “historic resistance to our answers” is however far from dogged contradicting or a unwillingness to listen, as the phrase seems to imply: it is rather that, unfortunately, the arguments brought in by various members amount to no more than refutations, some more dismissive than others, without showing where I am going wrong. Indeed, I see no attempt to lay out any refutation based on the principles of physics I invoked in the lever-boom analogy..
Your contention that in holding the boom it is the increased distance from the C.O.E. that requires more force and not the distance from the mast is true, but, interestingly, it does not disprove my analogy with the lever. It is just another way to put it, because the C.E.O., in the end, is the force of the wind which is to be resisted by holding the boom, just as in the lever-fulcrum context, the force to be overcome in lifting a weight with a lever is gravity and it varies according to the distance from the fulcrum, just as it varies depending on the distance from the C.O.E.
If my reasoning is based on misconceptions, these can only be dispelled by explaining them..
Finally, I never said that debate and explanation are “ sparring” or “ belligerence.
When I speak of sparring or belligerence I refer only to those who stray from a healthy debate by expressing their disagreement( or misunderstanding) in a way which is dismissive, curt, sometimes impolite ..
Unfortunately, Isobars, not everybody in this Forum ( and I guess in any Forum) is like you, or Swchandler or me.. You know it very well! This is why I enjoy debating with you all and hearing from you, even though I may not always agree.
Take care
Ittiandro |
|
| Back to top |
|
|
isobars
Joined: 12 Dec 1999
Posts: 20935
|
| Posted: Wed Oct 19, 2016 9:27 am Post subject: |
|
|
| ittiandro wrote: | | If my reasoning is based on misconceptions, these can only be dispelled by explaining them. |
Agreed, but I haven't the time. |
|
| Back to top |
|
|
U2U2U2
Joined: 06 Jul 2001
Posts: 5467
Location: Shipsterns Bluff, Tasmania. Colorado
|
| Posted: Wed Oct 19, 2016 9:58 am Post subject: |
|
|
| ittiandro wrote: | | isobars wrote: | Ittiandro, as an engineer with a strong emphasis on physics, I see many misconceptions in your posts about fulcrums, levers, etc as applied to WSing. I'm sorry that I don't have time to elaborate on them, but here are a few points.
• Until and unless you correct your basic misconceptions about where the fulcrums and levers are in WSing, physics will only confuse you...The further away your reactive forces are from the COE, the harder your muscles have to work.
• Swchandler knows and usually covers windsurfing topics very well and very clearly; don't blow him off for that reason. Here's my understanding of your quote of him (Swchandler resentfully said “ Guy Cribb? Why don't you just do what he says then? Why listen to me? Problem solved, right?”): If he's resentful, it's due to your historical and present resistance to our answers to your questions.
• Debate and explanation is neither "sparring" nor "belligerence" among adults. It's just debate, and if kept impersonal can contribute a great deal of information and options to readers.
|
I think we should really put this issue to rest, as you suggest, because to further pursue it from my original perspective would necessitate both of us venturing more deeply into physics, which is beyond the scope of a windsurfing forum, of no interest to most windsurfers and probably beyond the understanding of the average person, including myself (even though the physics of the lever are simple enough to be understood by any high-school graduate without having recourse to..Riemann’s geometry).
Before putting this issue to rest, though, I’ll only comment briefly on your remarks about my misconceptions and your idea that I have a” historic resistance” to the answers given by various members on this issue.
I may have misconceptions on the physics underlying these issues and you probably have, as an engineer, a better understanding than me..
What you call my “historic resistance to our answers” is however far from dogged contradicting or a unwillingness to listen, as the phrase seems to imply: it is rather that, unfortunately, the arguments brought in by various members amount to no more than refutations, some more dismissive than others, without showing where I am going wrong. Indeed, I see no attempt to lay out any refutation based on the principles of physics I invoked in the lever-boom analogy..
Your contention that in holding the boom it is the increased distance from the C.O.E. that requires more force and not the distance from the mast is true, but, interestingly, it does not disprove my analogy with the lever. It is just another way to put it, because the C.E.O., in the end, is the force of the wind which is to be resisted by holding the boom, just as in the lever-fulcrum context, the force to be overcome in lifting a weight with a lever is gravity and it varies according to the distance from the fulcrum, just as it varies depending on the distance from the C.O.E.
If my reasoning is based on misconceptions, these can only be dispelled by explaining them..
Finally, I never said that debate and explanation are “ sparring” or “ belligerence.
When I speak of sparring or belligerence I refer only to those who stray from a healthy debate by expressing their disagreement( or misunderstanding) in a way which is dismissive, curt, sometimes impolite ..
Unfortunately, Isobars, not everybody in this Forum ( and I guess in any Forum) is like you, or Swchandler or me.. You know it very well! This is why I enjoy debating with you all and hearing from you, even though I may not always agree.
Take care
Ittiandro |
If you had followed the first line of your post and put this to rest you would not have carried on for 5 paragraphs.
You AFAIK have posted 8 threads on THREE CONTINENTS IN regard to harness, and harness line placement. Some responses echo those above in regard to move the lines to suit , leave the physics, quantum mechanics , hydrodynamic phenomena .
Just to further a point that in no way reflects on this thread, I offered to send you I think for $10 a pair of fins for your BIC, which by anyone's standards is close to a give away. You never acknowledged not thanked me for the offer.
That is impolite
_________________
K4 fins
4Boards....May the fours be with you
http://www.k4fins.com/fins.html
http://4boards.co.uk/ |
|
| Back to top |
|
|
konajoe
Joined: 28 Feb 2010
Posts: 517
|
| Posted: Wed Oct 19, 2016 2:35 pm Post subject: |
|
|
Hi Ittiandro!
It's interesting to re-read your first few posts on this thread. I didn't read it close enough either!
So, if you want to think of the booms as two levers with the fulcrum at the COE, that's ok by me.
OK, so hands farther apart apart gives you more leverage. And you'll see that happen with the best sailors when overpowered. And, as you theorized, the best racers will move their hands very close together in light winds. There is a lack of 'feel' in light winds if the hands are far apart, because there is so much leverage.
Harness line width is another issue. When you're in the harness, it's not easy to selectively load the back or front line. So, it's common to see folks who always have their harness lines a fist width apart, no matter what the wind strength, but have their hands wider apart as the wind picks up, or gets gustier. |
|
| Back to top |
|
|
ittiandro
Joined: 22 Nov 2009
Posts: 294
|
| Posted: Wed Oct 19, 2016 4:53 pm Post subject: |
|
|
| U2U2U2 wrote: |
If you had followed the first line of your post and put this to rest you would not have carried on for 5 paragraphs.
You AFAIK have posted 8 threads on THREE CONTINENTS IN regard to harness, and harness line placement. Some responses echo those above in regard to move the lines to suit , leave the physics, quantum mechanics , hydrodynamic phenomena .
Just to further a point that in no way reflects on this thread, I offered to send you I think for $10 a pair of fins for your BIC, which by anyone's standards is close to a give away. You never acknowledged not thanked me for the offer.
That is impolite |
Please note that in my recent posts including my last one in response to Isobars, I abstained from continuing to argue WITH YOU on this issue, given the level reached. A level, which, I must say now, is a far cry from an intelligent debate,( both in the form and in the substance).
Perhaps more importantly, I also refrained from naming you in my last post, as the true paradigm of what I was telling Isobars is far from the spirit (and perhaps even the rules) of a Forum.
I did this for a basic sense of civility because, as somebody else has recently said “ When the others go low, we go high” …
I thought that the best way to protect oneself from the effects of mud slinging is not to continue throwing mud , but to withdraw..
However much there is that I object to in your post ( practically all) and however tempting it would be to fully respond , I ‘ll therefore say no more, also because you did the job: you shot yourself in the foot. Congratulations!
For whatever you care, let the others see you through your own words..
Ittiandro |
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You can attach files in this forum
You can download files in this forum
|
|
|
Search
Profile
Log in to check your private messages
Register
