UPDATE: I have made several sails for my little Skerry. [ READ ABOUT MY SAILMAKING EXPERIMENTS] I was in search of the perfect sail. I started with a nylon sail that worked well but eventually stretched. I then made this white polytarp sail. It worked really well for high winds but was not good for calmer conditions. My third sail was an orange polytarp and it was a very successful sail after some modifications. The Orange Polytarp sail became the pattern for a more permanent Dacron sail. I also added a small jib. The latest sail is the largest but my skill at sailing has increased enough that I'm comfortable in all but the strongest conditions.
Making a new White POLYTARP Sail
With this sail I wanted to address 2 issues. I wanted a smaller sail that was less hair raising than the previous one had been (I got caught in some very scary squalls) and I wanted a less stretchy better performing fabric than the nylon I had used to make my first spritsail
The sprit sail design proposed by the designer John Harris of CLC worked really well for me so I want to keep to that design for now. I decided to give polytarp a try. I had a large piece left over from the Skerry boat cover. At least it is white. I once again cleared the furniture from the workshop AKA the living room, and to my cats delight started making another sail. The polytarp was crumpled and this made it harder to measure accurately. I tried to integrate the seams already present in the tarp so it would not look too odd. I cut out the existing grommets though because they are not well set and not reinforced enough and they pull out.
First step is always 'remove cat from unfolded tarp. Edges being finished and corner reinforcement being placed. 2 cats assisting.
Marked the sail using dry erasable markers. Just rub the marks off when done! Stitched the edges. I put a binding on most of the edges except for the one that had a double layer in the tarp. That one I just folded under. Stitched using a triple zig zag. 3 layers of corner reinforcements.
I went over the sail and stitched a double line of zig zag along the edges and on all the patches. The sail now has a good solid feel.
The grommet holes in my first sail were too close together soon this one I measured a longer interval and melted the holes withmy soldering iron. it's easier than using a punch and this way thereis no unravelling of the holes. Also used the iron to finish thecorners. I stitched over the corners that have been rounded.
The grommets fit tightly in the holes and there is enough thickness to seat the grommet solidly. With this last step the sail is ready to be tried out.
This sprit sail is smaller than the previous one. The tack of the sail fits much better. I'm concerned about the creases coming from the boom to the mast. Maybe this is too tight. I will try it out then adjust. (As it turns out the creases seem to disappear when sailing.) The new sail is nowhere near as pretty as my first sail. sigh...
I used similar measurements to the first sail but made the foot shorter and adjusted other dimensions to make a balanced rig. You can see there is about 6 inches of extra boom.
Laced new sail on Skerry mast. Needs tweaking! Later I did re lace the sail and it fits much better. There is no shaping on this sail and all the lines are straight. This is not as serious as if the sail was made of dacron. The polytarp stretches and the sail acts as though it had some shape.
Finally I tested my new Skerry sprit sail.
After tweaking the attachment of the sail onto the boom it looked much better. I evened out the tension and it lost the creases that you see in the above photos.
I had a perfect sailing day. The best day ever. The white sail was perfect for the conditions, 12 knot wind with gusts to 18 and small waves.
The sail is easy to control, not as powerful as the nylon one and clearly not powerful enough in wind below 6 or so knots. It is also a lousy sail trying to go upwind. It tends to twist quite a lot.
This sail wasn't pointing very well and I have to figure out how to tighten-loosen the sail while under way from the back where I sit. My Boat is simply too sensitive to weight distribution to comfortably go to the front and adjust the downhaul and snotter when there is a lot of wind. I guess I would need to stop and let the sail go.
Arwen marine modified his rigging to bring the ropes to the backusing pulleys and a couple of cleats. I think I will try this. Meanwhile the new white polytarp is a success. I have a piece of bright orange heavy duty polytarp and will make a bigger sail next, about 6 inches lower than the standard Chesapeake Light Craft design for the Skerry. I can tilt my mast quite a lot so I can play with the balance that way. This should give me about 3-4 square feet larger sail area. Sail area is not an issue when there is good wind because the Skerry quickly gets to hull speed with the standard sail and it's pretty useless to try and push it beyond that, but there is often light wind and a larger sail would be useful in that case.
The White Polytarp was good for brisk days but did not work in low wind and was poor at going upwind. Time to make a new sail! Read about the Orange Polytarp sail.
UPDATE: The orange polytarp sail was a great success but finally stretched out of shape. I made a new red dacron spritsail and it rocks! It took 3 sails to figure out what worked best but I think this sail is as good as it gets ... maybe.Read about the latest Red Dacron sprit sail.
Read about other parts of my Skerry boat being constructed
This web site reflects my personal ideas and doesn't represent anyone else's point of view.