Sail Size Database
For the basics of how to balance a sail rig over your duck, see Design Your Duck
Yes, this is another one of my goofy non-standard ways of defining the way to do something, but I hope that after you "get it", hopefully you will agree this is a simple way to measure and layout a sail from polytarp. The idea behind this technique is to start with a polytarp, and quickly locate the corners of your sail, while also preserving the original edge of the tarp which already has grommets.
Parts of a sail
Here are some of the names for basic parts of a sail, plus my definitions of the parts used in this technique such as "up 1" and "over 1".
1 - Measure Up the Luff
Start at the tack, and measure up the luff. This will be the original edge of the polytarp you are going to preserve.
2 - Find the Clew
Find the clew by using "up 1", then across using "over 1"
3 - Find the Peak
If making a 3 sided sail, skip this step. If making a 4 sided sail, find the peak by using "up 2", then across using "over 2".
4 - Fold Your Dart(s)
3 sided sails usually have 1 dart, and 4 sided sails have 2 darts.
5 - Build the rest of your sail
Look at the other polytarp sail making instructions, and continue building your sail.
List of sail dimensions
Here are dimensions of some sails that people have used on their puddle ducks. The 3 sided sails will not have a dimension for head or up/over 2.
| Sail Name | Sqft | Luff | Up 1 | Over 1 | Up 2 | Over 2 | Foot | Leech | Head |
| Bolger 59 Leg-O-Mutton | 59 | 14' | 3'5" | 8'3" | --- | --- | 9' | 13'4" | --- |
| Texas Mutton (Everything in Texas is BIG) | 82 | 15' | 2'9" | 10'2" | --- | --- | 10'7" | 15'10" | --- |
| Abrahams Lateen | 57 | 12'0" | 6'5" | 9'6" | --- | --- | 11'4" | 11'0" | --- |
| PD Lug 74 (luff and leech reversed) | 74 | 12'1" | 1'9" | 10'10" | 6'2" | 8'4" | 10'8" | 4'10" | 10'8" |
Dart Sizes
Some of the voodoo magic of sails and odd materials is tweaking the size and location of the darts or curved luff & foot. Different people try different darts and their locations, so the size and location of the dart will change from person to person.
| Sail Name | Person | Up D1 | Over D1 | Dart Fold | Up D2 | Over D2 | 2nd Dart Fold |
| Bolger 59 leg-o-mutton | Shorty | 4' | 3' | 3" | --- | --- | --- |
Other Sail Sizes and Instructions
Steve Henshall - Cybernaught's Polytarp Sail Making MethodMitch Longtin - Balanced Lug Sail Details and Dimensions
Dave Gray - PolySail.com - making polytarp sails
Dave Gray - PolySail.com - sail size library
Jim Michalak - Jimsboats.com - Sail Area Math - calculate the size of sail and locating it
Jim Michalak - Jimsboats.com - Michalak Lug Sail Rigging Instructions
Jim Michalak - Jimsboats.com - Michalak Lug Sail Reefing Instructions