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p23brian

Another terminology question - "luff"

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I just watched one of John Barresi's videos and he used the term "luff".  On a sailboat this can be either a noun or a verb.  As a noun it means the edge of a sail that's closest to the front of the boat.   As a verb, it means to steer the boat slowly into the wind until the sails lose their lift.  This would be similar to pulling the top lines on a quad toward you and easing the bottom lines away from you until the kite was right on the edge of losing lift.  Is there a different meaning specifically related to kites?

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1 hour ago, p23brian said:

This would be similar to pulling the top lines on a quad toward you and easing the bottom lines away from you until the kite was right on the edge of losing lift.

I admit I may have been using the word luff rather casually without fully understanding its meaning. :)

However, the description above is certainly related, I've been calling that over-sheeting the sail (same way Revs fly without longer top leaders - lots of trailing edge flutter and loss of consistent pressure) - so much leading edge toward you, that the pressure slips off the trailing edge too easily.

Alternatively, I use luff to describe a simple loss in pressure - kind of like when you're flying along and all of the sudden a streak of turbulence or something causes the sail to lose pressure (regardless of leading/trailing edge angles).

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Except it's wrong!!! ;)  (Or at least it offends me as an almost lifelong sailor - been racing sailboats for 42 years)

The luff is the leading edge of the sail so that is also equally applicable to a kite.

However,  amomentary loss of pressure is a lull, not a luff; and over sheeting the sail is stalling it, not luffing it.

I'm not sure I would ever consider using luff as a verb in kite usage, but if it is remotely applicable then Brian's definition is the only one that would carry any weight with me: "This would be similar to pulling the top lines on a quad toward you and easing the bottom lines away from you until the kite was right on the edge of losing lift."

(P.S. Only my opinions of course.  Us Brits would never be dogmatic!)

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if you pull the top lines you create lift for kite,for that launching or lift is also named "thumb up".

is good to try to compare different "sails" but is a must to put them on the same situation.

Only my opinions of course  

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9 hours ago, John Barresi said:

I admit I may have been using the word luff rather casually without fully understanding its meaning. :)

However, the description above is certainly related, I've been calling that over-sheeting the sail (same way Revs fly without longer top leaders - lots of trailing edge flutter and loss of consistent pressure) - so much leading edge toward you, that the pressure slips off the trailing edge too easily.

Alternatively, I use luff to describe a simple loss in pressure - kind of like when you're flying along and all of the sudden a streak of turbulence or something causes the sail to lose pressure (regardless of leading/trailing edge angles).

Thanks!  Just trying to make sure I understand what everyone's talking about. :)  On a sailboat over-sheeting would be roughly the same as too much pull on the bottom lines of a quad (increasing AoA) until it stalls.  Sheets are the lines that control the angle of the sail to the wind.  Pull too much and the sail stalls.  Ease it out too far and the sail luffs.  You usually can't move the leading edge of a sail.  The headsail's LE is attached to the headstay (cable from top of mast to bow that holds the mast up).  The LE of the main is attached to the mast.

 

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Just want to add that I'm not criticizing anyone's use of terminology.  I just want to understand it, especially if it differs from mine. :)  Again, thanks for all the discussion.

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8 hours ago, jaydub200 said:

The luff is the leading edge of the sail so that is also equally applicable to a kite.

 

I attempted to simplify this by calling it the edge closest to the front of the boat because it seems on kites people refer to the leading edge as the top of the kite with the rod in it.  But depending on the orientation of the kite, the edge with the rod could be the trailing edge and the bottom of the kite could be the leading edge from an aerodynamic perspective. :)

My description of luff as a verb would be synonymous with pinching when sailing closehauled.  Sheet in all the way and head up until the sails start to luff; "luffing up".

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All good! :)

Part of what you're seeing here is the result of very little professional or high level sporting kite pastime - a lot of us have quite literally had to build a vocabulary around things that hadn't yet been discussed in such depth.

Great discussion, keep it up.

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Ok JB, 

Don't get me started on this "sailing" stuff.  We went down this road many years ago.  I bet you forgot that :rolleyes:

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By Tom Lochhaas, Sailing Expert
Definition:

Noun: The luff is the leading edge of a sail. On a mainsail, the luff attaches to the mast. The luff of a head sail, or jib, attaches to the forestay.

Verb: Luffing refers to a shaking or movement of the leading edge of a sail when it is not in trim. For example, if the sail is let out too far for the wind’s direction, the leading edge may shake or start to blow inward. Tightening up the sheet usually corrects luffing.

Verb: To “luff up” also refers to the act of turning the boat more into the wind, thereby causing the sail to luff. This may be done deliberately, for example, to slow the boat down to prevent crossing the starting line too soon in a sail race.

How that translates to kite flying I shall leave to those better informed than me.

Soggy.


Sent from my iPhone using KiteLife mobile app

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If you fly your Rev from the deck of a sailboat, would that be termed "double-luffing"? Or "penta-luffing", one single + one quad sail? What if you were fishing for crappie? Would anyone like cheese on their French fries?

Turning the boat more into the wind can be a really "tacky" move. 

Kiting does not translate into any language except Smile, one which everyone speaks.

Why are they called prevailing winds when they stop as soon as your kite is set up? Why do birds sing so gay? Why do fools fall in love? Why don't we get together and fly a kite? Come on, April -- are we there yet?

 

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