Draft stripes. Anyone use them?

Justin_NSA

Justin_NSA

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Jul 7, 2004
8,462
Hunter 30T Cheney, KS
I confess this is new to me. Anyone getting benefit from using them?

A draft stripe is a horizontal strip of dark colored sailcloth placed at one or more points along the luff on each side of a sail. Each stripe indicates the path of air molecules as they pass over the surface of the sail

UK Sails even has software that will analyze them


UK+Sailmakers+Draft+Stripes.jpg
 
kloudie1

kloudie1

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Nov 6, 2006
10,006
Hunter 34 Mandeville Louisiana
Very useful to mentally picture and set the halyard tension and outhaul tensions for draft/twist optimization.
 
DArcy

DArcy

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Feb 11, 2017
1,752
Islander Freeport 36 Ottawa
Draft stripes are very useful for understanding your sail shape. That picture you attached is a great representation showing the depth of draft but also where the point of maximum draft is for each of the 3 stripes. Sail shape is somewhat set by the loft when they make the sail but is also somewhat adjustable by halyard tension and sheet lead as mentioned above.

You can reduce draft by increasing halyard tension but this also moves it forward a bit. The sheet lead angle will adjust the twist which changes the shape from top to bottom.

In the illustration it looks like the top and bottom stripes are just about right with the max draft around 1/3 chord (distance from leading to trailing edges) but the middle stripe is bit farther aft indicating this sail has a bit of belly in the middle. Not a lot you can do about that pulling on strings, that is the cut of the sail. On a main, you can remove belly by bending the mast.
 
rgranger

rgranger

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Jan 19, 2010
12,548
Hobie 16 & Rhodes 22 Skeeter Charleston
I have them on my new genoa but I spend more time looking at the tell tales than the draft stripes.
 
Will Gilmore

Will Gilmore

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Oct 19, 2017
7,823
O'Day 19 Littleton, NH
"Anyone use them?"
Yes. Even if you don't pay attention to them specifically, an exprienced sailor will be looking at the sails, watching the luff, judging the twist, looking for leach flutter, etc. Draft stripes, even though I've never given them a thought, inform my eye of the trim of the sail, but also of the condition of the sail. If you know what a new sail should look like, draft stripes will tell you when you're sails are getting blown out.

I use to sail a Hobie 18 for many years, the brightly colored horizontal panels acted as draft stripes.

Where I a sailmaker, like @DrJudyB, I would always include draft stripes in a new sail build. It encourages a sailor to become conscious of the condition of old blown sails and get them replaced sooner. It is easy enough to live with blown sails when all you do is sail out of the harbor on pleasure cruises of only a few hours, but if every time you look up and see the evidence of your sail's condition and you say to yourself, I'm going slower than I should be because my sails are in bad shape, you will be more likely to come back and get a new sail sooner.

-Will (Dragonfly)
 
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Will Gilmore

Will Gilmore

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Oct 19, 2017
7,823
O'Day 19 Littleton, NH
Justin, is that a picture of your sails? The main looks back winded by the Jenny, but the sails look in awesome condition.

-Will (Dragonfly)
 
Justin_NSA

Justin_NSA

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Jul 7, 2004
8,462
Hunter 30T Cheney, KS
Will Gilmore said:
Justin, is that a picture of your sails? The main looks back winded by the Jenny, but the sails look in awesome condition.

-Will (Dragonfly)
Click to expand
Nope. I wish. I took it off of UK Sails. It's part of their software pitch.
 
D

dlochner

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Jan 11, 2014
12,327
Sabre 362 113 Fair Haven, NY
Draft stripes are most useful when the sail begins to age. You can see the draft move aft and the shape change.

Before then it helps to set the sail and get halyard, outhaul, and Cunningham tension correct on the main and halyard tension on the jib.
 
Tally Ho

Tally Ho

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Jan 7, 2011
5,264
Oday 322 East Chicago, IN
I was supposed to get them on my new North Sail main I had made...but they forgot to put them on.

I also have full batten, so those work pretty well to provide a visual of the sail draft...
IMG_0859.JPG


Greg
 

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Tally Ho

Tally Ho

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Jan 7, 2011
5,264
Oday 322 East Chicago, IN
dlochner said:
I hope they didn't charge you for the draft stripes. :huh:
Click to expand
Not “extra”, but I am sure it was included in the cost of the sail somewhere.
North did offer to have me bring it in, and they could apply them over the off season.

Greg
 
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Dalliance

Dalliance

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Oct 6, 2007
1,107
Hunter H30 1982 Chicago IL
I have them on both my main and genoa. I look at the telltales more often, but the draft stripes do help me read the sail shape when I might otherwise just see a bright white sail in the sun.
53DCC1B1-6C4A-48A0-8538-E15C20AF68AB.jpeg
 
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JRacer

JRacer

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Aug 9, 2011
1,350
Beneteau 310 Cheney KS (Wichita)
Oh yeah. Like your American Express. Don't leave the dock without 'em.
 
Jackdaw

Jackdaw

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Nov 8, 2010
11,386
Beneteau First 36.7 & 260 Minneapolis MN & Bayfield WI
A couple of quick thoughts regarding draft stripes. Unlike telltales, they are not a trim element but a shape element. That means they are not adjusted to nearly as regularly.

1) Definitely more usable with Dacron sails. The more high-tech your sails become, the more the shape is baked into them, and is not that changeable. If you see these new black north 3DIs, there’s not much shaping going on with those guys.

2) If you don’t adjust your jib or main halyard tension regularly based on conditions, or use your Cunningham, Then draft stripes will matter nothing to you.
 
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dLj

dLj

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Mar 23, 2017
3,877
Belliure 41 Back in the Chesapeake
Well, I've just learned something new. I first didn't look at this thread because I was thinking who the heck needs these on a sail boat???
1617243429307.png


But indeed, the subject is not this at all!!!! Draft stripes and Draft Marks are two different things...

dj
 
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Will Gilmore

Will Gilmore

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Oct 19, 2017
7,823
O'Day 19 Littleton, NH
dLj said:
Well, I've just learned something new. I first didn't look at this thread because I was thinking who the heck needs these on a sail boat???
View attachment 192265

But indeed, the subject is not this at all!!!! Draft stripes and Draft Marks are two different things...

dj
Click to expand
I was actually thinking draft marks are a great idea on a sailboat. Put them on the bow and the stern and use them to be sure your trim is level when tuning your rig and setting your rake. Of course, there is the boot stripe.

-Will (Dragonfly)
 
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