STIRLING MARBLEHEAD YACHT RACING CLUB Inc.

Woorabinda Lake - Stirling South Australia

SAIL MAKING - Choosing and Sourcing Sail Material  
by Ben Morris (last edited 08/06/2021)

Shape in Sails

Building Board

Making Seams

Set the Seam Curvature

Making a Sail

Sail Material

Diagonal Seams etc

Back to Intro page

Setting the Sails

The Claudio Tool

Measuring Procedures

 

Choices of Sail Material

The type of material used by sails determines the effectiveness of the airfoil shape.  There is a forward force acting on the sail material  attempting to fold the material forward and potentially creasing the sail.  This is balanced by the pressure difference on either side of the sail forcing the material flat.  The problem is compounded where there is a significant roach to support as well.  These issues can be dealt with in three ways.

• use a  material which is essentially rigid - too stiff and light winds will be unable to force it to the correct shape; too flexible and the folding issues arise

• reduce the amount of roach in sail - may not be possible as design may define shape e.g.; Marblehead designed with significant roach, IOM define shape even more precisely.

• use longer battens - even full length battens to support softer material and large roach - may not be legal e.g. Marblehead & IOM define length of batten but 10R yachts have no such restriction.

In addition the sail material should be as smooth as possible, easily worked and cuts easily, holds well with double-sided tape and has no permanent set or curl .  I have used a variety of materials and indicate their properties below.

 

Material	Properties	Availability
Code Zero 1.7oz	Mylar film laminated to very light Dacron? cloth with diamond shaped carbon fibre reinforcing between,  Tough as old boots, does not crease readily strong and will not tear readily, sticks well especially Mylar side, fairly smooth, quite stiff but often has a slight curl - need to alternate panels	Radio Yacht Supplies Australia Radio Sailing Shop
Code Zero 2.1oz, 2.3oz, 2.9oz	Probably overkill for strength - these have some Kevlar between laminations, surface is  not as smooth and not as rigid as 1.7oz	Radio Yacht Supplies Australia Radio Sailing Shop
Ripstop polyester 0.7 oz	Very light  and difficult to manage but very good for a super light wind situation.  Not to be confused with the nylon (polyamide) Ripstop spinnaker material, unaffected by water and quite stretch resistant	Radio Yacht Supplies Australia Radio Sailing Shop
Dacron sail cloth 3.3-4.4oz	Not much experience with this but dimensional stability and stretching can be an issue.  Seams probably need stitching to hold	Radio Yacht Supplies Australia Radio Sailing Shop
Mylar drafting film 25, 35, 50 and 70 micron (1.2, 1.5, 2, 2.2 mil or thousandths of an inch)	This is probably the material of choice.  It is smooth strong, easily cut and stuck with little or no permanent curl - alternate panels anyway to cancel.  However, it creases easily so don't fold it, it can tear readily if a small cut is made on an edge so protect all edges with adhesive Mylar tape	Radio Yacht Supplies Australia Radio Sailing Shop Midwest Model Yachting from America Floataboat in Melbourne.  See website then contact them for catalogue by e-mail
Mylar film from florist	tough and stable but quite difficult to work, very lightweight	florist or florist suppliers
White probably Mylar film described as tracing film	as per thicker Mylar film but is a laminate and can delaminate if resetting seams quite good really	premier art suppliers

 

There are probably other materials to try but that should get you started.