Genoa measuring, help please. - SailNet Community
Reply
 
LinkBack Thread Tools
post #1 of 14 Old 11-16-2013 Thread Starter
Member
 
budvar's Avatar
 
Join Date: Mar 2013
Location: Tri-Cities, Wa. USA
Posts: 51
Thanks: 29
Thanked 2 Times in 2 Posts
Rep Power: 4
 
Genoa measuring, help please.

Hi!

I am in the market for new/slightly used Genoa for my US Yacht 25. I took my trusty 30' tape measure and took measurements.

I'm getting confused with regard to the foot of the sail, and the J, and the LP.
Some websites with sails listed show only the sail's Luff and Foot. I guess I'm getting confused when it comes to the foot. Other sites show the Luff and L/P. What should I be looking for when a seller only lists the luff and foot.

Here's my measurements:
Headsail Luff: 26' 3" max.
LP: 11' 3"
J: 9' 7".

Goal is a 133% Genoa.

Thanks for any help!

Chris
Richland, Wa.
budvar is offline  
Quote Quick Reply Share with Facebook
Sponsored Links
Advertisement
 
post #2 of 14 Old 11-16-2013
no longer reading SailNet
 
Alex W's Avatar
 
Join Date: Oct 2012
Posts: 2,309
Thanks: 2
Thanked 140 Times in 133 Posts
Rep Power: 5
 
Re: Genoa measuring, help please.

There are two jib calculators that I find helpful:
Jib Overlap Calculator
http://l-36.com/LP_calc.php

Both will compute LP for you given sail size. The L-36 one will also compute foot height relative to tack if you know your forestay angle.

I'm no longer participating on SailNet.
Alex W is offline  
Quote Quick Reply Share with Facebook
The Following User Says Thank You to Alex W For This Useful Post:
budvar (11-16-2013)
post #3 of 14 Old 11-16-2013
Senior Member
 
JimsCAL's Avatar
 
Join Date: May 2007
Location: Glen Cove, NY
Posts: 3,563
Thanks: 3
Thanked 129 Times in 121 Posts
Rep Power: 10
 
Re: Genoa measuring, help please.

You really should look at the headsail area. You can calculate the area using Luff x LP/2 = Area. If they give you luff, leach and foot, you'll have to do a some geometry/trig calcs to get there. If they only give you the luff and foot, you will have to guess. The LP will be less than the foot, but it depends on how high the sail is cut. Looks like for your boat I=30.27' and J=9.5' so 100%=30.27x9.5/2=143.8 so 133% would be 191.2 square feet.
JimsCAL is offline  
Quote Quick Reply Share with Facebook
The Following User Says Thank You to JimsCAL For This Useful Post:
budvar (11-16-2013)
post #4 of 14 Old 11-16-2013
Senior Member
 
Join Date: Feb 2010
Location: Narragansett Bay
Posts: 13,881
Thanks: 64
Thanked 337 Times in 317 Posts
Rep Power: 8
   
Re: Genoa measuring, help please.

This might help.

US 25 sailboat specifications and details on sailboatdata.com


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Jeanneau 54DS

In the harsh marine environment, something is always in need of repair. Margaritas fix everything.
Minnewaska is offline  
Quote Quick Reply Share with Facebook
The Following User Says Thank You to Minnewaska For This Useful Post:
budvar (11-16-2013)
post #5 of 14 Old 11-16-2013
no longer reading SailNet
 
Alex W's Avatar
 
Join Date: Oct 2012
Posts: 2,309
Thanks: 2
Thanked 140 Times in 133 Posts
Rep Power: 5
 
Re: Genoa measuring, help please.

I'm looking for a smaller headsail now (leaning towards having a new one made) and find it useful to look at both sail area and LP. You can have 133% LP sails made to almost any sail area by varying the luff length of the sail. On a 133% it is unlikely that you'd make the luff length short, but on smaller sails (<100%) they are often cut that way.

I also find that doing a search on sailritesails.com will give you target dimensions for common sail sizes on your boat. Here is a link to your boat (the second genoa listed is about a 135%):
http://sailritesails.com/ShowAd.aspx?id=6486&sourceid=2

The sail for my boat that will be about 200sqft. A 200sqft sail for my boat (39' forestay, 37.5 I, 11.25 J) could be made as a sail with a roughly 32' luff and 14' foot (around 105%, called a working jib), or with a 36' luff and 11' foot (around 95%, called a blade jib). Both have the same sail area, the aspect ratio and LP are just different. The blade seems easier to tack.

I'm no longer participating on SailNet.
Alex W is offline  
Quote Quick Reply Share with Facebook
The Following User Says Thank You to Alex W For This Useful Post:
budvar (11-16-2013)
post #6 of 14 Old 11-16-2013 Thread Starter
Member
 
budvar's Avatar
 
Join Date: Mar 2013
Location: Tri-Cities, Wa. USA
Posts: 51
Thanks: 29
Thanked 2 Times in 2 Posts
Rep Power: 4
 
Re: Genoa measuring, help please.

Thanks to everyone for the great help! Much appreciated.

Chris
Richland, Wa.
budvar is offline  
Quote Quick Reply Share with Facebook
post #7 of 14 Old 11-18-2013
Senior Member
 
Sabreman's Avatar
 
Join Date: Sep 2006
Location: Yeocomico River, VA
Posts: 1,643
Thanks: 3
Thanked 18 Times in 15 Posts
Rep Power: 12
   
Genoa measuring, help please.

BTW. For virtually all masthead rigs, when you do the trig, foot and LP are virtually the same.

Sabre 38 "Victoria"
Sabreman is offline  
Quote Quick Reply Share with Facebook
post #8 of 14 Old 11-18-2013
no longer reading SailNet
 
Alex W's Avatar
 
Join Date: Oct 2012
Posts: 2,309
Thanks: 2
Thanked 140 Times in 133 Posts
Rep Power: 5
 
Re: Genoa measuring, help please.

If virtually means within 20%, then yes, you are correct. It depends on the angle of the foot to the luff and the angle of the forestay.

I check filter as a first gauge, but still do the actual LP calc to check percentage overlap. I also check square feet if the sail that I'm looking at doesn't use the full luff.

I'm no longer participating on SailNet.
Alex W is offline  
Quote Quick Reply Share with Facebook
post #9 of 14 Old 11-18-2013
Senior Member
 
overbored's Avatar
 
Join Date: Oct 2010
Location: Dana Point, Ca
Posts: 1,776
Thanks: 1
Thanked 110 Times in 109 Posts
Rep Power: 7
 
Re: Genoa measuring, help please.

Quote:
Originally Posted by Sabreman View Post
BTW. For virtually all masthead rigs, when you do the trig, foot and LP are virtually the same.
I must be using different trig then you. it would make the sail makers job a lot easier . all sails would be square. the LP and foot can never be the same on a triangle sail.

"FULL TILT II" 2011 BENETEAU FIRST 30
"GOLD RUSH" PRINDLE 16

Last edited by overbored; 11-18-2013 at 02:13 PM.
overbored is offline  
Quote Quick Reply Share with Facebook
post #10 of 14 Old 11-18-2013
Senior Member
 
mikehoyt's Avatar
 
Join Date: Nov 2000
Posts: 687
Thanks: 0
Thanked 1 Time in 1 Post
Rep Power: 17
 
Re: Genoa measuring, help please.

run a tape up your forestay attached to the halyard. That gives you a good idea of the luff length you can use. LP is easily determined by measuring shortest distance from the clew to the luff. Divide this by your boat's J measurement and you have LP.

Mike

Mike

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
mikehoyt is offline  
Quote Quick Reply Share with Facebook
The Following User Says Thank You to mikehoyt For This Useful Post:
budvar (11-18-2013)
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
Measuring Tool wind_magic Gear & Maintenance 25 10-08-2013 12:39 AM
Measuring a foresail Gregrosine General Discussion (sailing related) 4 07-10-2013 08:46 PM
Measuring stainless dimension. GMC Gear & Maintenance 7 06-12-2012 01:12 PM
Measuring Battery Voltage ccriders Electrical Systems 6 11-13-2010 07:41 PM
Measuring Boat Speed Dan Dickison Racing Articles 0 07-02-2002 09:00 PM

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