PolySail International

High Performance/Low Cost Sails for Small Sailboats



Constructing My Favorite PolySails:

The Michalak Piccup Pram Lug Sail

By Dave Gray


            Constructing this sail from one of our PolySail Kits is a simple three to six hour project, depending upon whether one chooses to stitch up the sail before use or simply use the taped up sail. Of course, we always recommend that a sail be sewn as soon as the tapes begin to loosen. The following photos outline the steps I use in constructing a simple lug balanced lug sail. This lug can be a powerful sail on a small pram or dinghy. The center of effort is lower compared to most triangular sails, and often the mast and spars can be short enough to be stowed in the boat.


Step 1  Mark Out the Sail Dimensions

            For this sail project, you will need a 10’ x 12’ Pram Kit. Unfold the white tarp and stretch it out as flat as possible. On a concrete or other flat surface, use weights at the corners. I use one-gallon paint cans. On dry grass, use tent stakes or long spikes to spread out the tarp. Next, mark out the sail dimensions. Use an erasable marker to mark the corners and at each foot along the luff, leech, and foot. I find it helpful to tape down the tape measure in two or three places so that the edge doesn’t move much while marking these straight reference lines.

Using an erasable marker allows you to make reference marks directly on the sail surface and then erase them by rubbing them lightly with your finger.




Novices sometimes ask why they can’t simply use the grommeted edges for a sail edge. The simple answer is that these tarp edges are straight, and straight edges aren’t appropriate for most sails—except for the leech where the edge grommets would disturb the air flow. Futher explanation follows in Step 3.


Step 2  Placing V-Darts (See the generic instructions for a diagram showing how to make V-Darts)

            A lug sail needs camber or belly near its forward edge to draw well. To create this camber, I usually place a fairly large V-Dart in the tack, the corner nearest the mast, and a smaller V-Dart in the head of the sail. The head is the edge that begins near the top of the mast and ends at the peak or highest point of the sail. To allow for the V-Dart in the tack of the sail, I usually leave a 2” gap at the tack between the luff and foot as seen in the first picture below. I usually place a 1” x 12” V-Dart in the tack. First, I fold a V shape into the tack. Next, I add a triangle of double-faced tape to one side of the V. Finally, I remove the backing on the double-faced tape and close up the V-Dart.  V-Darts must be placed in the sail before the edges are taped  Consequently, the sailmaker must “rough cut” the outline of the sail or create “notches” in the tarp where the V-Darts will be placed before the edges are taped and the final outline of the sail is formed. Because V-Darts will affect the sail measurements, always recheck your sail measurements after inserting V-Darts in corners and edges of your sail.


 Step3 Taping the Edges

            With the reference marks down, the next step is place the double-faced tape. Taping the leech is fairly straightforward. Place the tape along the leech just to the outside of the marks you’ve made defining the leech. There is no roach or rounding in the luff or leech of this sail, so the big challenge is to make a straight run with the tape from the peak to the clew for the leech and from the throat to the tack along the luff edge.. On the other hand, the tape in the head and foot must be rounded correctly to help create camber (curvature) in the body of the sail and in order to create a proper foil shape.  I usually eyeball these curves with the maximum of 2” rounding in the head.  For the foot, I round the edge so that the inside of the tape is at its maximum of 2 ½” at 3’ from the tack.


Step 4 Cutting Out the Sail Outline

            Once the tape is in place, you can begin to cut out the sail shape. Using a sharp pair of scissors, begin at the throat (the corner next to the upper part of the mast) and cut along the outside edge of the tape along the luff. If your scissors are sharp, you should be able to run the scissors along the edge of the tape, slicing the material, without even closing the shears. Continue cutting counterclockwise around the sail until the sail outline is finished. Save the scrap. The edge material will be used later in the process for making corner reinforcing strips.




Step 5 Taping in the Rope Reinforcement

            Lay out the reinforcing rope around the edges with one end protruding about three inches from the tack.  Peel back the paper backing from the fiberglass-reinforced tape at the tack and fold the overlap over the rope at the tack corner. Next, place a weight on the overlapped corner. Stretch out the rope and the luff edge and place a similar weight on the rope and material at the throat of the sail. Work up the luff, removing a few feet of tape backing at a time and folding over the overlap. As you work, remove the erasable markings by rubbing them with your finger.. Repeat this process for the head, leech, and foot making certain that the leech is straight and that the head and foot have a fair curve. Once the overlaps are taped down, I pound down the overlaps with a rubber hammer—on the advice of an adhesives expert from 3M.



Step 6 Reinforcing the Corners

            From the edge strip you removed in Step 4, cut out two similar edge strips for each corner of the sail. For the tack, the length should be adequate to cover the V-Dart or about 12”. For the head and clew, the pieces should be about 10”. Place double-faced tape on one side of each edge strip and trim up the edge material to the width of the tape, then trim the ends as shown. These strips will have the effect of distributing the strain on the corner grommets into the body of the sail. Once these strips are in place, add vinyl tape (shown in red in the pictures) to the corners for additional reinforcement. I use two strips of vinyl tape placed diagonally at each corner. Cut the tape so that it overlaps the edges and can be wrapped around to the opposite side. Cut the corners off the tape diagonally as shown below in the first picture on the second row. When you add tape on the reverse side, follow the same procedure in order to construct a finished corner.



Edge material and a strip with tape backing shown cut to size.


Cut the vinyl tape so that it

overlaps the sail edges by about ¾”


Nip the corners off this strip of tape before wrapping it around the sail edge.



Step 7 (Optional) Stitching the Perimeter

            After the corners have been reinforced, you must decide whether you want to stitch up the perimeter of the sail. If you really can’t wait to get out on the water, you can skip sewing the sail and begin grommeting the corners and luff. If you decide to stitch up the perimeter, on the other hand, it helps to have a sewing machine with a walking foot and an edge guide like the one shown below. Use V-69 polyester sail thread or a similar thread for the seams. After stitching down the reinforcing strips and tape in the corners, I run a straight stitch around the perimeter of the sail about 1” in from the edges.


Step 8 Placing the grommets

            In my custom-made sails larger than 50 sq. ft., I usually place a larger 7/16” brass spur grommet in each corner just to the inside of the reinforcing rope. I place slightly smaller 3/8” grommets evenly along the foot and head. The combination of vinyl tape, corner reinforcement strips, rope reinforcement, and stitching makes for exceptionally strong corners in this sail.

When the sail is finished, it can be attached to the mast with the cable ties supplied with the kit or with rope or commercial mast hoops. Mast hoops can also be made by sawing ¾” strips from a large diameter piece of PVC water pipe. Make certain that you file down any sharp edges. One of the better sites for pictures showing how to rig the Leg o’ Mutton sail is at Michael Storer Boat Design. Michael, an Australian designer and racer, has created a photo essay showing how he rigs his PDRacer at this site: http://www.flickr.com/photos/boatmik/sets/72157594524425079/ 


The Piccup Pram lug sail can be built in other configurations by stretching the dimensions. For a smaller pram or dinghy, this sail is ideal. Below is the finished sail except for the grommets.






This 280 sq. ft. lug was constructed for a Roberts 27. The foot of the sail is over twice as long  as the PDRacer .


This Bolger  Windsprint lug at 113  sq. ft. is a great sail for a 16-18’ boat. Note the reef points


Custom British Balanced Lug

Shellback Dinghy  Balanced Lug

Custom Balanced Lug

My 100 sq. ft. PDRacer lug sail

John Nystrom’s 55 sq. ft. PDRacer lug sail

Standing lug with   4--batten leech for Welsford Rogue


For additional information and diagrams of constructing balanced lug sails from polytarp, click on this link.


PolySail International

2291 SE Gaslight St., Port St. Lucie, FL 34952-7332

 Email polysail@polysail.com or call Dave Gray at 317 385-3444

PolySails–Sold on the Web since 1996. Customers in all 50 states and around the globe.


This page updated on 2/8/20010