Determine ounce (oz) weight of sails?

[esarratt]

I have some sails that came with my boat. How do I determine the ounce weight of the fabric?

[Cheechako]

A seasoned sailor can guess close. You can bag them and take to your local sailmaker and ask him what they are.

[Spot]

I am not as seasoned as Cheechako. Below is the same method I use with random pieces of fiberglass cloth when I don't know what weight it is:

I would weigh the sail in kilograms and come up with a square area in meters (a=1/2*b*h for a basic triangle), adding in some area for tape and corner reinforcements and taking off weight for bolt ropes, hardware, etc..Then do the math for GSM (grams per square meter) and compare it to basic GSM numbers from a sailcloth company. Your number may not be a 100% match but should be close enough to indicate one or another cloth weight.

PS on Sailselect.com it's made mentioned of 'English' and 'US' oz/sqyd...that is why I said use GSM.

[hpeer]

English or American? And other inscrutable concepts!

Cloth weight - SailSelect

https://en.m.wikipedia.org/wiki/Sailcloth

Weaving Edit

Combed singles yarn sailcloth in high counts is used for spinnaker and head sails. The count often is 148 by 160 and the fabric is finished at 100 cm (40 in) wide with a length-to-mass ratio of about 13.10 m/kg (61⁄2 yd/lb).[1] The quality and weight of the weave can be more critical than the choice of fibers, since a poor weave can lead to high stretch and poor sail form. Weight is described in ounces, for example "an 8 oz. cloth". This means that an area of 72 cm × 91 cm (28+1⁄2 in × 36 in) weighs 230 g (8 oz).

Or ..... find out your sail measurements and weigh it. Then to Bacon Sails and search for sails close to those dimensions and find a sail that weighs close to yours. Then look at what weight cloth it is.

And I bet you thought it would be easy!

[esarratt]

Ahhh! That's the trick.


The sails are the originals; they were made by Ratsey and Lapthorn when they had a New York loft.


I will measure the sails, weight them and send R&L send pictures of the sails along with the year my boat was built. I bet they will know the weight.


Thank you all for your help and ideas.

[hpeer]

I found the original invoice and rough dimensions for my boats original suite of sails, along with cloth weight - specified as “English Ozs.”

That was a good find as it informed me of how the designer intended the boat to be sailed. Which was a LOT different from the sails she had when I bought her. Which contributed to some “issues.”

[ggray]

As far as weighing and measuring the square yards of material, is it sail cloth or fiberglass cloth that while weight is quoted "per yard" it's not square yard, but running yard of "standard width" which isn't 36 inches.

I'm fairly certain this is true for one, or perhaps both of these clothes, and could steer you off on what you actually have.

[StuM]

Originally Posted by ggray

As far as weighing and measuring the square yards of material, is it sail cloth or fiberglass cloth that while weight is quoted "per yard" it's not square yard, but running yard of "standard width" which isn't 36 inches.

I'm fairly certain this is true for one, or perhaps both of these clothes, and could steer you off on what you actually have.

Correct for "American Ounces.
According to Sailrite:
SAILMAKER’S YARD: A 28.5" x 36" sample area that measures the weight of sailcloth. For example, 6.5 oz. sailcloth means that a 28.5" x 36" sample piece of that sailcloth would weigh 6.5 ounces

However, the "English Ozs" mentioned by hpeer are based on a 36" x 36" yard.
There's a table comparing English Oz, Sailmakers (US) Oz and g/m² here:
http://www.sailselect.com/our-sails/cloth-weight




Added: I see hpeer linked to that page in his earler post

[Jim Cate]

Yet another place where moving to a metric measurement would resolve some ambiguity issues. g/sq meter is hard to mis-interpret!

Jim