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Mach 3 question

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Created by mikey100 > 9 months ago, 15 Jul 2020
seanhogan
QLD, 3424 posts
25 Jul 2020 9:32AM
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don't know why my post appears like a quote..... weird


You can tighten the leash with this rope.

Pulling it will make the leash a bit more tight and less open.

Ben1973
957 posts
25 Jul 2020 8:29AM
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Pretty sure it's not a leach line, very weird place and way of attaching one.

dkeating
VIC, 256 posts
8 Aug 2020 10:34PM
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Ben1973 said..
Pretty sure it's not a leach line, very weird place and way of attaching one.

My R7 s have the same string so been there on a few models.
Would not make sense as a tell tail as sewn at both ends and if one end was loose you would not see it from the normal sailing position as its too close to the top of the sail.
You could tie on a streamer but you could do this with only the white loop.
Also don't understand why the R7 reflexes have 2 plastic and 2 metal pulleys on the down haul.

Ben1973
957 posts
9 Aug 2020 8:42AM
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The pulley things makes sense and is still uses on the mach's and ODs. It's probably to save money as the first 2 take lower load so don't need to be metal

Pacey
WA, 525 posts
9 Aug 2020 11:38AM
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Ben1973 said..
The pulley things makes sense and is still uses on the mach's and ODs. It's probably to save money as the first 2 take lower load so don't need to be metal


The tension is equal on all parts of the purchase, but the sheaves rotate by different amounts as the tail is pulled in. So the sheave closest to the tail will have more Revolutions and more wear than the sheave at the other end, so a more durable material would be preferred. Its a good tradeoff between weight and durability.

Subsonic
WA, 3118 posts
9 Aug 2020 4:08PM
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seanhogan said..


You can tighten the leash with this rope.


Pulling it will make the leash a bit more tight and less open.



Its there to re-tension something, im sure. Its quite common to see a piece of string left dangling in other forms of sail (yacht and dinghy sails) but about as commonly used (Almost never).
im gonna take a closer look next time i've got a sail unrolled.

Subsonic
WA, 3118 posts
9 Aug 2020 9:32PM
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Subsonic said..


seanhogan said..






You can tighten the leash with this rope.




Pulling it will make the leash a bit more tight and less open.





Its there to re-tension something, im sure. Its quite common to see a piece of string left dangling in other forms of sail (yacht and dinghy sails) but about as commonly used (Almost never).
im gonna take a closer look next time i've got a sail unrolled.



It could from memory also be there to drop tension from the leech as the rest of the sail stretches.

Ben1973
957 posts
10 Aug 2020 6:09AM
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Pacey said..




Ben1973 said..
The pulley things makes sense and is still uses on the mach's and ODs. It's probably to save money as the first 2 take lower load so don't need to be metal






The tension is equal on all parts of the purchase, but the sheaves rotate by different amounts as the tail is pulled in. So the sheave closest to the tail will have more Revolutions and more wear than the sheave at the other end, so a more durable material would be preferred. Its a good tradeoff between weight and durability.





Wrong. The last pulley takes more. Just look at it when your pulling the last pulley always ends up lower. If the pulleys had zero friction then it would be the same.
your rotating answer is also correct.

Pacey
WA, 525 posts
10 Aug 2020 6:46AM
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Ben1973 said..

Pacey said..





Ben1973 said..
The pulley things makes sense and is still uses on the mach's and ODs. It's probably to save money as the first 2 take lower load so don't need to be metal







The tension is equal on all parts of the purchase, but the sheaves rotate by different amounts as the tail is pulled in. So the sheave closest to the tail will have more Revolutions and more wear than the sheave at the other end, so a more durable material would be preferred. Its a good tradeoff between weight and durability.






Wrong. The last pulley takes more. Just look at it when your pulling the last pulley always ends up lower. If the pulleys had zero friction then it would be the same.
your rotating answer is also correct.


Really? Maybe you are doing it wrong or have crappy pulleys. A multi-purchase system will equalise so that all parts have the same tension unless there is significant friction in the system.

This is my Mach2 6.2, looks equalised to me:

Ben1973
957 posts
19 Aug 2020 9:07AM
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I think looking at that your pulleys are a lot newer than mine.
still haven't found the answer to the original question, everyone know about the short white loop but no one the long red loop.

Subsonic
WA, 3118 posts
19 Aug 2020 1:36PM
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I had a look the other day and it doesn't go down the leach.

You mentioned severne replied saying something about "streamer system". Some PWA events require/d a rider to display a set of streamers off the top of the sail so the race committee could readily identify which heat they were competing in. The streamers I believe were issued right before they left the beach between heats so maybe the string is put there for a quick fastening point for the streamers?



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"Mach 3 question" started by mikey100