Why round sail edges if there going to be tied to the mast and boom - SailNet Community
 1Likes
Reply
 
LinkBack Thread Tools
post #1 of 15 Old 05-08-2013 Thread Starter
Junior Member
 
Join Date: May 2013
Posts: 23
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
 
Why round sail edges if there going to be tied to the mast and boom

I just dont get it, Why should I round the edges of my sail if once there tied to my mast and boom are just going to be flat. Am I missing something here? Its fustrating. Or are you supposed to keep the sail a couple inches off the mast and boom by attaching them looser. I understand rounding/ hollowing the leach but why the the foot and luff.

I read this somewhere else it makes no sense to me

"By rounding the edges of your sail, you will provide some curvature to the sail when the rounded edge is straightened against a mast or boom."

Last edited by MattMcc804; 05-08-2013 at 01:10 AM.
MattMcc804 is offline  
Quote Quick Reply Share with Facebook
Sponsored Links
Advertisement
 
post #2 of 15 Old 05-08-2013
Senior Member
 
SchockT's Avatar
 
Join Date: May 2012
Location: North Vancouver, BC
Posts: 1,440
Thanks: 1
Thanked 28 Times in 26 Posts
Rep Power: 4
 
Re: Why round sail edges if there going to be tied to the mast and boom

If you are referring to luff curve, it along with broad seaming is how you get depth into the sail. When the mast is straight, the sail shape will be fuller. As you bend the mast it stretches that material between the luff and the leech and makes the sail flatter. Remember that most masts are not straight, they have a certain amount of pre-bend when sitting at the dock, and will bend even more when the backstay and sheet are on hard. The sail must be cut to match that pre-bend.
Faster likes this.

1979 Santana 30 Tall Rig
Hull#101

Last edited by SchockT; 05-08-2013 at 02:45 AM.
SchockT is offline  
Quote Quick Reply Share with Facebook
post #3 of 15 Old 05-08-2013
baDumbumbum
 
bobmcgov's Avatar
 
Join Date: Jul 2007
Location: Windy Wyoming
Posts: 1,126
Thanks: 0
Thanked 36 Times in 35 Posts
Rep Power: 9
 
Re: Why round sail edges if there going to be tied to the mast and boom

Luff and foot rounds were how draft was introduced to bolt-roped sails, especially in the absence of broadseaming, especially in small low cost boats. If you attach a convexly curved sail to a straight spar, a baggy pocket is generated near the mast and boom. Fill it with wind, that excess cloth becomes your airfoil shape. Not an especially great airfoil shape, but it was a cheap and quick way to accomplish that end. The preferred way to induce draft, especially with modern, low-stretch synthetics, is to build in draft by curving the seams between panels (broadseaming). This allows you to control the draft location and depth much better. But it is more labor-intensive than just cutting a luff curve. For the ultimate in airfoil shaping, sailmakers have begun molding the panels over three dimensional dies to get curvature just right. That's really expensive.

The other reason to build a positive curve into your mainsail luff and foot is, as ShockT notes, because most masts and many booms (esp. with mid-boom sheeting or vangs) exhibit a certain degree of bend. If your sail's luff and foot were straight, any flex in the spars would pull all the draft out of the sail and cause embarrassing creases. This Wayfarer mast pre-bend is a bit exaggerated, but you get the idea:



On some boats, pre-bend is critical for driving upwind, esp. in chop. It can also help the mast resist bowing forward downwind, which can be bad. Depends on the boat, tho. BTW, most headsails have a negative (concave) luff curve, to accommodate headstay sag.

Buccaneer18, Grainnia
SJ21, Diarmuid
Albin Ballad 30, Fionn
bobmcgov is offline  
Quote Quick Reply Share with Facebook
post #4 of 15 Old 05-08-2013
Senior Member
 
SchockT's Avatar
 
Join Date: May 2012
Location: North Vancouver, BC
Posts: 1,440
Thanks: 1
Thanked 28 Times in 26 Posts
Rep Power: 4
 
Re: Why round sail edges if there going to be tied to the mast and boom

Bobmcgov,

your post implies that luff curve is something that was done in the past. It should be noted that cutting curve into the luff and leech remains an important part of modern sailmaking, even on the most advanced sail designs. It is not just the domain of "cheaper" sails.

1979 Santana 30 Tall Rig
Hull#101
SchockT is offline  
Quote Quick Reply Share with Facebook
post #5 of 15 Old 05-08-2013 Thread Starter
Junior Member
 
Join Date: May 2013
Posts: 23
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
 
Re: Why round sail edges if there going to be tied to the mast and boom

Wow this sail making stuff is quite confusing isnt it, no wonder they cost so much money.
I dont mind putting hours and hours into a sail I enjoy that stuff but it seems like ill be spending way more time trying to figure it out. Ill get a book
MattMcc804 is offline  
Quote Quick Reply Share with Facebook
post #6 of 15 Old 05-08-2013
Barquito
 
Barquito's Avatar
 
Join Date: Dec 2007
Location: Madison, WI
Posts: 2,267
Thanks: 0
Thanked 27 Times in 27 Posts
Rep Power: 8
 
Re: Why round sail edges if there going to be tied to the mast and boom

Quote:
Ill get a book
I think someone mentioned in another thread that Emiliano Marino's Sailmaker's Apprentice, is a good resource. I agree. Or, if you don't want to figure our how, and just wnat to do, then you could also just order a kit from Sailrite.

Bristol 27
Cirque
Barquito is offline  
Quote Quick Reply Share with Facebook
post #7 of 15 Old 05-08-2013
Senior Member
 
Join Date: Jan 2011
Posts: 763
Thanks: 0
Thanked 19 Times in 19 Posts
Rep Power: 5
 
Re: Why round sail edges if there going to be tied to the mast and boom

Latteen sails should be cut flat. Polytarp Sails is simply mistaken about this. The shape is introduced by allowing the boom to rise at the end.
Frogwatch is offline  
Quote Quick Reply Share with Facebook
post #8 of 15 Old 05-08-2013
Just another Moderator
 
Faster's Avatar
 
Join Date: Sep 2005
Location: New Westminster, BC
Posts: 16,563
Thanks: 110
Thanked 317 Times in 302 Posts
Rep Power: 10
     
Re: Why round sail edges if there going to be tied to the mast and boom

I think you're overanalysing all this.. as an auxilliary kayak sail it can be pretty simple. You're not trying to with the America's teacup, and it's never likely to go as well to weather as you paddling...

Ron

1984 Fast/Nicholson 345 "FastForward"

".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)
Faster is offline  
Quote Quick Reply Share with Facebook
post #9 of 15 Old 05-08-2013 Thread Starter
Junior Member
 
Join Date: May 2013
Posts: 23
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
 
Re: Why round sail edges if there going to be tied to the mast and boom

Quote:
Originally Posted by Barquito View Post
I think someone mentioned in another thread that Emiliano Marino's Sailmaker's Apprentice, is a good resource. I agree. Or, if you don't want to figure our how, and just wnat to do, then you could also just order a kit from Sailrite.
Ordered it a few hours ago, Ill have it in 2 days

Last edited by MattMcc804; 05-08-2013 at 03:56 PM.
MattMcc804 is offline  
Quote Quick Reply Share with Facebook
post #10 of 15 Old 05-08-2013 Thread Starter
Junior Member
 
Join Date: May 2013
Posts: 23
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
 
Re: Why round sail edges if there going to be tied to the mast and boom

Quote:
Originally Posted by Faster View Post
I think you're overanalysing all this.. as an auxilliary kayak sail it can be pretty simple. You're not trying to with the America's teacup, and it's never likely to go as well to weather as you paddling...
I dont paddle anymore and can maintain 4 knots in 10 mph winds. And thats with a rugged plywood leeboard and it has to create lots of drag. And thats with a 20sq ft poly tarp sail crudely made, I dont know if it can tack well yet but ive been able to sail away and sail home. Once I get my book Im going to sew something nice from 4oz dacron, A bermuda if I can figure it out. Oneday I would like to use this sailing triak in the everglades challenge a 300 mile race/expedition to the everglades. Of course, I have a long way untill then. One benift is I live on the water and sail, and learn everyday
MattMcc804 is offline  
Quote Quick Reply Share with Facebook
Reply

Quick Reply
Message:
Options

By choosing to post the reply above you agree to the rules you agreed to when joining Sailnet.
Click Here to view those rules.

Register Now



In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.


User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Forum Replies Last Post
Mast & boom MSO sailor General Discussion (sailing related) 8 01-18-2013 06:31 AM
C&C 32 boom and mast cec513 Gear & Maintenance 3 01-13-2013 11:31 PM
ladder tied to mast? RNC725 General Discussion (sailing related) 4 03-19-2012 11:31 AM
mast vs boom jnanjorl Gear & Maintenance 13 05-25-2010 04:51 PM
Charleston edges Mattoon in soccer regional (Journal Gazette & Times Courier) NewsReader News Feeds 0 05-18-2006 12:15 AM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome