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03-27-19 03:17PM
Tony Hladun is offline Click Here to See the Profile for Tony Hladun Find more posts by Tony Hladun Add Tony Hladun to your buddy list Edit/Delete Message Reply w/Quote
Tony Hladun
Harvey Hacksmasher

 

Registered: Feb 2019
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Scratch Sweeping Dilemma

I've made two posts about corner sweeping and I've gotten counter arguments from supporters of the currently in vogue scratch sweeping school. Being a physicist let's do one of Einstein's thought experiments (Gedankenexperiment). If diagonal scratch sweeping can generate sufficient forces to change a rock's direction, then why won't sweeping across the face of a rock result in the scratches reducing the rock's travel? If scratch sweeping is true all of us curlers have got it all wrong and sweeping perpendicular to the rock path will actually reduce how far a rock slides. Yeah sure!

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03-27-19 03:29PM
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nervous_times21
Harvey Hacksmasher

 

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Tony - what you propose is exactly what happens. While only limited results from the NRC study were published, those that were suggest exactly that: sweeping perpendicular to the direction of rock travel "carries" the rock less than other sweeping directions. The "scratchier" the head, the less the rock traveled.

Note specifically the difference in the distance traveled by the red stones (non-confirming broom) between the first and last illustrations in figure 2 on the linked page.

See results here: https://www.curling.ca/national-res...cutive-summary/

Speaking of everyone "getting it wrong" - I think the average club curler has the advantage (in this case) of using old broom heads and a less-aggressive stroke than your average tour player. As a result, most curlers are probably using something akin to a WCF-approved head, which, as the results indicate, yield results agnostic to the sweeping method.

Last edited by nervous_times21 on 03-27-19 at 03:31PM

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03-27-19 03:57PM
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Tony Hladun
Harvey Hacksmasher

 

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Ah, horror stories and the Frankenbroom. The information in the post above doesn't address what I said. There is no comparison of a non-swept rock to sweeping using a legal WCF broom.

But let me get this straight, you're saying that all those tour curlers sweep to make the rock stop sooner? If nothing else we should at least get the commentators to stop misleading everyone.

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03-27-19 05:36PM
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Harvey Hacksmasher

 

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Fair enough - I did note that there was not illustration for the control - ie, the non-swept rock. The study looked at impact on rock path, not how far sweeping can extend the distance a rock travels.

But I wouldn't dismiss it so quickly - what I think is interesting about the study is that it shows that with a conforming head being used by some of the "best" sweepers (since we don't know let's assume that "best" means high stroke rate coupled with lots of weight on the broom), the ability to control the path by more than a rock-width is eliminated and stroke path has limited impact on distance traveled when compared to non-conforming heads.

To my eye, it looks like you get two more feet of distance sweeping on an angle than you do straight across the face. (sure, whether you get more distance by not sweeping at all is not addressed by the NRC diagram).

I may be missing your point again - but wonder if you would be interested in doing an experiment. We're about to get some 45 hours of curling coverage during the men's worlds - time draws hog to hog (or hog to stop, whatever you like), chart the paths, the amount of sweeping, and where the rock ends up. It's imperfect, but my own experience suggests rocks are going to travel farther (as measured by longer times) with sweeping.

As a PS - I don't think many curlers, club or tour, sweep perpendicular to the path of travel. My gut suggests something closer to 45 degrees is the norm - easier to keep moving with the rock.

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03-27-19 06:40PM
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Tony Hladun
Harvey Hacksmasher

 

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The sweeping alternatives in the study are too vague to draw any real conclusions other than Frankenbrooms had a huge impact.

On either of my two previous posts I posted a link and a time in one of Chelsea Carey's games that illustrated what I consider corner sweeping errors. I didn't refer to that here because I was commenting on the scratch theory.

Hits, draw arounds and run backs are determined by inches (fractions of maybe) so the sweeping effect does not need to be large. One rock width is massive. If you look at the Swedes and Swiss they stayed away from corner sweeping and went home winners.

I'm looking forward to the men's championships. Do they corner sweep the wrong side and do they miss those shots is all we need to look at. Remember though it's not the side the sweeper is on but it's the side he/she is sweeping. The stronger sweepers reach over and really make a mess. Also if the skips are complaining about the ice it's possible the sweepers are the problem.

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03-27-19 09:03PM
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nervous_times21
Harvey Hacksmasher

 

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Well, I tried to engage with your thought experiment. If you're going to ask the question, you should do better than simply waving away alternative reasoning.

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03-28-19 12:00AM
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Tony Hladun
Harvey Hacksmasher

 

Registered: Feb 2019
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Well if you want an honest answer I didn't engage because your assertion that a swept rock stops sooner is just wrong. I agree with Curling Canada who in this study https://www.curling.ca/blog/2010/10...eeping-secrets/ said: "It was found that top sweepers could extend the path of the stone by 6 to 7 feet over the final 1/3 of the sheet. " I believe this study was done before the Frankenbroom debacle and the scratch obsession so the brooms used were more like they are now.

Last edited by Tony Hladun on 03-28-19 at 12:13AM

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