Go Back   Starboard Forums > Free Forum

Reply
 
Thread Tools Display Modes
Old 6th July 2010, 10:41 PM   #1
Cmarois
New Member
 
Join Date: Jul 2010
Posts: 3
Default How to calculate the sail size

Hi everybody,

I have a sail that I wish to sell, and I'd like to provide the size of the sail ( which I don't know and it's not indicated).

I originally searched online for the methods, which I did not find, so I guessed it was similar to calculate the area of a triangle.

So here is what I came up with:
My sail is 13.5 feet tall, 7 feet at the boom. I converted that to meters which gave me 4.11 meter tall and 2.13 meters at the boom.

After doing the calculation : (4.11*2.13)/2, it comes down to 4.3 square meters.

so I thought my sail was of size 4.3. But someone came and compared what is supposedly a 4.5 sail, and it's half the size of mine.

So therefore, how do I calculate the size of the sail, since apparently it's not what I thought.

Many thanks in advance.
Chris.
Cmarois is offline   Reply With Quote
Old 6th July 2010, 11:54 PM   #2
Unregistered
Guest
 
Posts: n/a
Default

Well if the 4.5 is half the size of yours that would make it a 9 meter! But with a 411cm mast that's pretty doubtful I'm guessing that the shape of your sail and the 4.5 are quite different, so it's difficult to accurately compare their sizes.

This is probably a pretty old sail? Does it have any full battens; ones that go all the way from the leech (trailing edge) of the sail all the way to the mast?

One minor adjustment would probably be in the mast sleeve - it's probably curved so it's not quite a triangle.

If it's old enough, it might be marked with the area in square feet. Then you can convert using: sq ft x 1.1 = sq meters

You can always just sell it with a picture and the mast & boom measurements.

Drew
  Reply With Quote
Old 7th July 2010, 12:03 AM   #3
Farlo
Member
 
Join Date: Aug 2006
Posts: 527
Default

Hi Chris, unless your sail is very old fashioned it has not a triangle shape and there is much surface outside. Based on my own sails collection I would suggest a x1.4 factor so ~6.2 m². This been said 4.11 sounds very compact for a 2.13 boom. I have a 7.3 m² sail with same boom length and 4.86 mast luff. What type of sail is yours?
Farlo is offline   Reply With Quote
Old 7th July 2010, 03:46 AM   #4
Cmarois
New Member
 
Join Date: Jul 2010
Posts: 3
Default

Thanks for the replies.

I think it's somewhat old. I am not the original buyer. And it's a NeilPryde (or something like that).
The battens are not full length (3 in total), and it's not far off from a triangular shape.
I looked everywhere on it, and it does not say anything about the size.

The measurements I took are approximate with a measuring tape, but I mean, in worst case it's an error margin of 1/2 feet.

As for the other 4.5, you could clearly see it had a lot less surface. It was approximately the same luff length, just half the width.

I'll try to post a picture to give a general idea.
Cmarois is offline   Reply With Quote
Old 7th July 2010, 06:32 AM   #5
joe_windsurfer
Member
 
Join Date: Apr 2009
Location: Montréal (PQ) CANADA
Posts: 211
Default

did an experiment since i have my sail specs in a spreadsheet

did reverse engineering and discovered luff * boom / 1.5 is REALLY close to sail size

so, in this case ...

4.11*2.13/1.5=5.836 sq meters
rounded up that's a 6.0 sail - make sense ??
__________________
joe windsurfer @ 100 kg
2006 AHD type-F FF 160/79cm, 2002 BIC Techno Formula, 2000 Fanatic BEE 124 LTD + Mistral Equipe I LCS
HSM Fire 6.3, Gaastra Flow 3x 7.0, TR-6 8.4, TR4 10.0

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
joe_windsurfer is offline   Reply With Quote
Old 7th July 2010, 08:47 PM   #6
Ken
Member
 
Join Date: Aug 2006
Location: Dallas, Texas USA
Posts: 799
Default

Sounds like a 25 year old regatta sail. Short mast and long boom with three short battens. Is the sail all Dacron (no plastic laminate on the sail), with a thick flexible window?

Given the mast and boom sizes, it my be around 5 - 5.5 meters. I still have my 1985 Superlight regatta sail and use it on the original board.

Are there any markings on the main body of the sail (numbers or a design)?

Any pulleys or just a grommet at the foot of the sail?
__________________
Toys:
Formula 160; iSonic 111; HiFly Move 105; Tiga 263; '85 Mistral Superlight.
Maui Sails TR 11.0; 9.2; 8.4; 7.6; 6.6; Maui Sails Switch 6.0; 5.2; Maui Sails Global 4.5; 4.0.
Ken is offline   Reply With Quote
Old 7th July 2010, 10:25 PM   #7
Cmarois
New Member
 
Join Date: Jul 2010
Posts: 3
Default

Joe and Ken, thank you very much.

The sail is pretty much how you describe it, Ken: no laminate, small plastic window, no marking or number, and it's a grommet at the bottom.

Joe, I was dividing by 2, so your 1.5 is probably what I had wrong.

With a visual comparison (from memory) with the 4.5 sail, 5.5 or 6M would make sense.

I'll go with that.

Thanks for all the help, guys!

Chris.
Cmarois is offline   Reply With Quote
Old 7th July 2010, 10:55 PM   #8
nonopr
Member
 
Join Date: Aug 2008
Location: San Juan, Puerto Rico
Posts: 573
Default

There is an Application on iTunes that gives you the sail size depending on your weight and wind velocity.
The name is Sail Size.. Check it out. They also offer a windows excel program with the same things.
http://www.vims.edu/general/sailpadd...calculator.xls
http://www.vims.edu/general/sailpadd...calculator.xls

Last edited by nonopr; 7th July 2010 at 10:59 PM.
nonopr is offline   Reply With Quote
Old 8th July 2010, 03:23 AM   #9
Unregistered
Guest
 
Posts: n/a
Default

Good Lord Sir !
By the sound of your sail, it is more likely you will be paying somebody to take it away !
I recently saw some wallets in Tarifa made from "old sail cloth".
You might do better to "recycle" it some other way.........
  Reply With Quote
Old 8th July 2010, 04:01 AM   #10
Floyd
Member
 
Join Date: Sep 2006
Posts: 459
Question

Hi
Its a little off topic but a technique I use to compare my sails (from different manufacturers/ranges) is boom length x mast length (in cm) divide by 1000.

A 7 metre comes out around 100. A 5 metre around 70. Its sort of a power index which I find better for comparing sail "sizes" than quoted areas.

See where yours comes out and then work backwards to size.
Floyd is offline   Reply With Quote
Reply

Bookmarks

Tags
None

Thread Tools
Display Modes

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 Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Isonic 133 what fin size for sail size. Nick F Ask Our Team 3 31st May 2010 05:58 AM
Max sail size in PWA? Unregistered Free Forum 4 30th May 2010 07:46 PM
Sail Size vs Mast Size/Weight robwootton Windsurfing School 3 24th March 2009 05:32 PM
Sail size on 162 Crash Ask Our Team 1 11th March 2008 12:00 AM
Fin Size/Sail Size Roly Gardner Windsurfing School 2 7th February 2008 04:27 PM


All times are GMT +7. The time now is 09:09 PM.