Wednesday, March 23, 2011

Lots o' patches

Each of the four corners of the Lug need additional reinforcement to bear the load and distribute it to the rest of the sail without failure.  My references agree that the size of each patch should be about one inch of length per foot of sail.  Since I'm working in metric anyway, I just decided to use a 10% rule of thumb.  I had considered getting fancy with the shapes of the patches, but I came to realize that simple triangles would be easiest to sew, given the fact that the sail is full size now.

I worked it out on paper first.  Each patch edge is 10% of the sail's edge, which makes for unequal sides and sizes.  At first I had thought to have more symmetry, but I didn't like the look on paper.  This drawing doesn't reflect the actual shape of the throat patch though.

I made paper templates first.  This would allow me compensate for the edge tapes as well as to make note of the cloth's weave direction.  The proper technique is to match the weave of the patch to the weave of the sail to prevent puckering or other odd transfer of strain.

This cutout comes from a patch on the luff, not the leech seen in the previous photo.

The guidance is for three or four layers that are set back at least an inch from each other.  I chose to divide the exposed portion of the largest patch (i.e. what is not covered by the edge tape) into thirds.

Leech patches

Luff patches

Peak patch
The reefing the sail reduces the length of the sides.  I scaled the intermediate reinforcements to match the length of the sail at that point.  The result is the graduated sizes above.

The one patch that isn't triangular is at the throat.  Many sails  feature a semi-circle at this point, but I continued my 10% scheme and found that it results in a miniature version of the full lug itself.  Once I realized that would be the shape, I was hooked.

Here they all are.  This clearly shows how each patch is different in size.  It looks a little awkward since they're so close to each other, but I'm confident they'll look good once they're attached.

 I'm glad I took the time to lay out the sail and position all the patches because I found out that the throat and the peak were not shaped correctly somehow.  I would have noticed when trying to sew them on of course, but I'm glad I found out earlier.

Some awkward rolling of the cloth was required to stitch each patch.  I did three seams in this direction, unrolled to the next patch and repeated.  Then I opened the whole sail again, this time rolling on a different axis to do the other seams.  Fun, but time consuming.

I haven't yet attached the throat or the peak patches.

Next up: edge tapes

Thursday, March 17, 2011

Taking shape

Things dried up in my neighborhood enough for me to roll out the full sail today.  Wow!  It's big!  Generally, I'm very pleased at the amount of shape I can discern from just laying out in my driveway.  How she sets when bent on spars in a fresh breeze or under "brutal downhaul" (that's an official Storer term) remains to be seen.

 This view is from atop a ladder that is set down hill of the sail.  More important are the wrinkles.  This shows that the cloth is not flat and will develop some shape when filled with wind.

 I rotated the sail and shot this pic from a window of my house.  Neither photo captures how tall this sail is.  It's over 5 meters or 17.5 feet tall.

These two pics are from opposite ends of the luff.  I pulled a chalk line out to compare the edge curve to a straight line.  This is the luff which is meant to be straight.  At over 2 meters or 6+ feet long, the amount of deviance is slight.  When it comes time to stitch on the edge tape, I will pull this edge taught.  What ever excess shape there is will be pushed into the body of the sail, creating more draft.

 This is what I was most interested in.  This is the head of the sail, looking from the throat to the peak.  This amount of rounding is what will match up with the yard's shape as it bends under tension.  During light to moderate winds, there will be less tension on the yard and this amount of excess cloth will be free to fill with wind and create a nice foil shape.  Under stronger winds, the downhaul will be tightened, the yard will flex, and the sail will flatten to about what is seen here.  Or so the theory goes.

Next up: corner reinforcements.

Sunday, March 13, 2011

If Drunken Monkeys Sewed... might look something like this:

For some reason, my sewing skills took a dive with my last two seams today.  Could be the longer length was too much for one person to guide smoothly.  Could be the machine was not happy.  Nonetheless, I've stitched together all the panels of the sail.  I haven't laid it out flat yet because we have some very soggy ground right now.  But as soon as I can, I will.

View from the leech looking forward.  This seam strikes right in the middle of the luff, which is where I need to generate the most shape.

View from the luff.  The pencil mark is 10mm from the edge, so you can get a feel for how much curve is being built in.

After taping, the wrinkles confirm that the sail is not flat.  Is it shaped enough?  Only time will tell.

Starting to get a little wacky.  There's another section similar to this, but most of the seam is fairly even.

This is IT!  The foot of the sail joins the rest.  I'm very pleased that Sailcut put this seam right at the tack.  Maybe it's 40mm off of the very point of the corner, but given all the corner reinforcement patches that are going to cover the corner, it's essentially a tack seam.

Again, the "broadseam" is about 20mm or so.

Not only did I have trouble keeping the seam spacing uniform, I also ran out of bobbin within about a meter of completing the seam.  Grrr.  Of course, these flaws all occur in the seams that are closest to the crew.  This couldn't have happened way up at the peak; that would have been too easy...

I'm happy with the result so far.  Again, I'm not shooting for perfection.  I just want something I can point to and say "I did this myself."  Sadly, the evidence is clear that I did.  No worries.

Next up will be corner patch reinforcements.  I haven't yet settled on a design for those and I think I'll mock them up with paper first to get a feel for different shapes.


Thursday, March 10, 2011

Assembly begins

It's time to start building this thing.  I got three of the six panels joined, starting with the smallest (the peak) and working my way down.

Production moved from my basement den to the main livingroom of the house.  I measured double the sail's longest seam to allow the full length in front and behind the sewing machine. It just barely fits...

The first seam.  This has little to no shaping.  A good way to start getting the feel for the process.

Double sided tape is essential, at least for my level of skill.  Much gratitude goes to the good folks at, not only for the tape and other materials but also for a great collection of free videos available online.  They gave me the confidence that mere mortals can do this and showed me a good technique for taping.  Highly recommended.

Voila!  Rolling both ends gave me good control over the work as it fed through the machine.  I used tiny spring clips, simply because I had them handy.

Perfect? No. Pretty darn good? Methinks so.

Seam two.  This how far I got before things went awry.  I suspect the glue from the tape was gumming up the needle.

Eww.  This is the back side.  Most of the gather thread is from the top side, not the bobbin.  I was able to pick it all apart, smooth the holes somewhat, and clean off the needle before restarting.  The remainder went without a hitch.

The third seam.  Not we're beginning to get some shaping (the far end from this view).

Shaping seen from the other end.

That puckering is the amount of draft produced once the two edges come together.  This seam stitched up with no problem.  Somehow I forgot to shoot a pic, but I think you get th idea.

So that leaves me with half a sail.  Well, something less than half since all the reinforcements have to be done too.  Stay tuned...

Wednesday, March 9, 2011

"That's it; now I gotta cut ya..."

I turned our family room into a sail loft for two days and cut the six panels of the sail.  A real lofting job involves nailing the rough dimensions into the wood floor, marking lines on the same, laying the fabric out all at once and tacking them to the floor here and there.  None of that can take place in my basement.  The next best thing for me was to work on one panel at a time, using some heavy plywood sheets to play the role of loft floor.  I can honestly say that if I didn't have the computer prinouts of each panel's dimensions, I could never have done this (in my basement, which means not at all).

So this is my psuedo-loft.  I aligned the edge of the cloth to the straigth edge of the plywood.  Not shown in this picture is the metric tape measure used to determine the X-axis coordinates, left to right from this view.  The t-square with metric ruler alongside was used to determine the Y-axis coordinates.  The hammer is for tapping a small nail into place.  I thought I was going to use the nails as flex points for a batten.  That didn't happen because the wood moulding I bought far the purpose was not stiff enoughpast a half meter or so.  Plus, the curves involved were so slight, a straight line between points was virually the same as a faired curve.

The string in this picture also didn't last long.  I quickly moved to using the ruler when possible, or other methods to be shown shortly.  Notice the dimensions on the plan?  That's in millimeters--to one decimal place!  Yeah... I SO was able to place my 1.5mm nail at precisely Y=875.3mm.

This is the second panel from the peak and the two nails describe a portion of the head round along the yard.  The next panel contains the point where head and luff meet (the throat).  Honestly, this did not feel like the 50mm of round I plugged into SailcutCAD.  I'll have to check that out once the panels are stiched together.

The shape of the draft starts here.  I didn't capture how far along the chord length this is (or even which panel this is) but this is the point where shaping of the seam begins to depart from a straight line.  In traditional lofting this would have been marked by hand after all the panels were laid out and would have been placed by traditional formulae or by a well seasoned eye.  I have none of that. Thank you Mr. SailcutCAD Computer Dude.

From there, the shape Gradually makes its way inward (upward?).  The ruler is placed up to the leading edge in this pic, so that the seam's end is 590mm away.

...which is here.  So this panel's curve goes from 14.5mm to about 1.5mm over the span of 590mm, and then to zero over another meter or so.  Since the ruler happens to show the imperial measure in this pic, it's clear that I have achieved a 1/2" broadseam whose maximum draft is way past the 590mm mark.  I suppose the gradual slope of this line defines the entry angle of the luff (if indeed this seam is endin at the luff, it could be hitting the head--I forget which panel this is).

We don't need no steenking plotter!  This is the bottom panel and the curve being drawn will define the shape of the foot.  I suspect there will be too much round to lash this foot to the boom; I think SailcutCAD assumes a loose-footed boom.  Anyway, the wood shown here is two strips of scrap luan ply I had on hand, clamped together so I could have a straight edge long enough to reach from tack to clew.  It worked.  SailcutCAD describes all intermediate coordinates in terms of their deviation from the straight line between the endpoints.  For all other panels, that straight line was parallel with the edge of the plywood.  In this case, the line cuts diagonally across the cloth.  Here, the wood is the tack-clew line and the pencil is pointing to the "deviation" point.  Who'da knew sailmaking could be so geeky?

I didn't photograph the panels themselves because I quickly rolled and stored them as the came off the "loft."  Shown here is all the excess material, which will go toward the corner and reef reinforcements.

Next time: panel assembly.