I was impressed by Vics tall skinny AIRTRACK 4.5m sail a few weekends ago so when sn dropped a bundle of monofilm and dacron on the doorstep O thought Id better have a go at something.
the sail i started with is and ezzy 5.6.
whtever you think of ezzy's as windsurfer sails I gotta say they are tough.
I had to cut the battens out of this one with a cutting disk in the grinder
thats a first for me.
I was looking for a tall flat rear panel with the roach falling backwards like this
the bar on the sail represents the FIRST cutting line . once marked I cut the sail about 50-75mm into the waste part of the sail as it will change shape once cut. after cutting out the rear panel I layed it back on the floor and remarked the cut line. I have the luxury of having the space to draw full size profiles on the shed floor for reference throughout the process .
this allows you to check each step to make sure it fits and to make subtle changes to the next sail
in these 2 images you can see how the original cut changed its line afterthe first cut. now i restretch it on the floor,redraw and recut. Im trying to create a completely flat panel witha very straight leading edge. note that the battens are almost perpendicular to the trailing edge of the sail
here you can see how the trailing edge will vary when compared to my other cl5 sails(the red line)
sorry for the delay in the posts on this one,Im waiting for my daughter to explain why her computer doesnt scan like the other one
the next part of this sail is to create the luff panel. I have a full size template made from flooring vinyl,which makes life kinda easy,but you could mark it out on a floor or work bench/sewing table
heres how its made. firstly draw a box4500mm long x250mm at the bottom and 180mm at the top
next the "centre"is marked 2200mm from the bottom.this will be where the maximum curve is measured from
at the centreline a point 170mm forward of the edge of the box is marked and an even curve is marked along the leading edge of the panel. then the rear of the panel is marked from a line 25mm out from the rear line of the box..
when Im making shorter sails for the minis I use 20mm on the back and still 170mm at the front.the dimensions here are for a sail that will be 4.6m along the luff and have an area of 5.3-5.5m
as this sail is a tall skinny one the overall width of this luff panel is going to be narrower. the width is determined by deciding on the width of the sail at the mid point and caculating 35% of the width.that will be the width of the luff panel at the centre line. for a fuller sail, use 40% and for a flatter sail 30% .
the material for the luff panel needs to be lighter and more flexible than the monofilm Im using. so on this sail Ive sacrificed an old cruising sail that had large 6oz dacron panels 2 peices cut from the sail made a long enough strip .
i wouldnt recomend usng monofilm for the front panel.I have done it before but it would never set flat and would get awful creases which eventually snapped.
the matching of the very straight flat rear panel and the subtly curved luff panel is the key to getting a shape out of this sail. next time I will talk about the tricky job of getting monofilm to be sewable.
sorry for yet another delay.
so the luff pocket has been cut from the template andsewn onto the rear panel . when sewing monofilm to dacron or even monofilm to monofilm its important to have a layer of cloth rather than the mylar film on each surface , I add a layer of 10mm dacron thape or in the case of this sail a line of double sided tape then a strip of dacron.
if you have stitching hard against monofilm ,it cuts into the thread
the long cut outs of the batten pokets have been cut off extending about 50mm into the dacron luff panel,then the new pockets sewn on in the same weight of dacron as the panet to give an even stretch.
the mast pocket has been saved from an early 90's Tiaga . often those sails are stuffed and delaminated but the pockets are fine
the foot of the ezzy had some cracked and flogged monofilm , so I cut off the lower 200mm of the sail and added a soft panel of material called flex13. this will help give a cleaner wrinkle free shape on the foot. I also gained 0ver 250mm more length.
rather than eyelets Ive used stainless steel shadecloth rings held on with webbing recovered from discarded bike helmets
make sure you get a good solid overlap on the bottom panel to the monofilm
heres a pic of the finished tack(front )
A strip of webbing has been added to the pocket to tuoghen t up and prevent tearing
heres an idea of all the sails that have been sacrificed for pockets,webbing ,battens and material on this project
after all this the sail is ready to fit on a mast , to make sure there is a good fit ,particularly at the head
sorry for further delays. the sail has been finished ,tested photographed etc,with some great results. subsequently i went back into the shed whilst cyclone Rusty was dumping on us and made version 2 . managed to do some critical damage to the sewing machine.
then we gave up and went lake hunting,and found a great spot ,so tommorrow will be sailing on water again
heres the sail "finished and rigged,sorry about the angle.looks great but when you look at the head a problem is obvious
with this amountof slack in the head the sail will flap and cause the front wheel to lift so its back to the sewing table before it even gets sailed
the head was unpicked and tightened by pulling the panels closer and resewing. I think this is one of the advantages of this type of construction for amatuers as the alternative is fiddling with the luff curve or the pocket
here it resewn and ready
heres the lower panel in flex13 or you could do it in dacron ,say5.5 or 6oz.
with monofilm you can get some odd wrinkles when fully sheete here but with a softer materials the sail sets better and is easier to fill at slower speeds.
here's a photo sailing ,with the outhaul right off as the wind is only low-15knts i reckon the no2 batten (1 is the top) needs to be filed and no 1 also. when flattened it was too flat for this wind. I did notice that once up to speed it was great and stable BUT when the wind dropped suddenly it would die and not pick up after the lull. more work on technique for this sail is needed
here it is sailing , but not fully sheeted . i had a volunteer in the yacht so i could take photos. . the sail really twisted the chassis with its big head , so much so that I cracked the mast step , requiring the yacht to be stripped and rewelded
ive already started on version 2, which i think will be a beter match to the airtrack inspiration, but Ive busted my machine
as Im waiting on ordered parts I thought I could put up some pics of the next sail in comparison the next sail is taller,skinnier in the head and slightly longer in the foot.here is the profile comparison,with the faint red lines the profile of a full 5.5m sail
here Ive placed a batten along the leach to show the difference better
heres the difference in the length of the foot,sail 1 underneath and shorter,sail 2 lifted slightly for east viewing
finally the big difference in the head. taller but with a narrower head so it wont twist as much in the gusts . it will be interesting to see how different it performs
finally got the sail finished thanks to chooks Dad
apparently if you soak a frozen thread like a engine bolt or a little SS batten adjuster in deisel, and then pop it in a freezer for a few days then they come unstuck
i put 9 adjusters in the freezer and got 5 working which is great as i needed 5
new battens fitted and on to the mast for a check up
the sail is sitting very nicely with one slight wrinkle in the middle ,which i think will pull out as the stitching stretches and the sail settles in
now all we have to do is get a dry lake to play on
What did Promogirl have to say about dieselly stuff living in the freezer 
stephen
need something tidal
