Erik and Evi Menzel Ivey wrote:

But I don't like going beyond a 3x1 sheet (if I get to keep it as a single sheet) due to the total length that ends up in the cockpit.  As it is, with our 5.8m wishbone booms, we have 30m long sheets.  I've not done the math on the sheet length for the junk sails, - with the shorter booms/sheetlets, and that go all the way up the leech - but I'm guessing the sheet may be shorter.  In any case, it is still my hope to get away with a single 3x1 sheet for each sail. 

Erik

Dealing with long sheets isn't an issue, as long as you get yourself organised properly.  The best way, I've found, is to have a deck box with a lid that lifts back over centre (so stays open even when the boat is heeling to put them in.  That way, even from a pram-hood steering position, you can just pile the surplus sheet back in the box.  If you are happy to sail from the cockpit, the lid angle is less important.  You just pick up the sheet that you hauled in and dump it in the box, (without, of course, capsizing the pile).  Sheets do not need the sophistication of flaking down, but prefer not to be coiled.  I am less fond of bags (a personal opinion - lots of other people seem to like them) because you can't usually just lift up the sheet and pile it in and, IMHO, they are an inelegant solution.  Your lidded box, on the other hand, if carefully thought out, can also provide a comfortable extra seat in the cockpit.  You can have one each side, for halliard and sheet, and in your case, have an athwartships separator to keep them from getting tangled together.

I tried several ideas on Fantail, none of which was successful, and was at the stage of contemplating a box when I decided to build another boat

Sheeting: Remember to extend the top sheeted batten aft of the leech. This makes a big difference to the behaviour of the top sheet span, the one that is most likely to get caught when the sheet is slack. As Darren says, I meant upper and lower sheets. I tried port and starboard sheets, and found that they weren't necessary on the fore sail, which doesn't need to be sheeted in as much as the after sail. I did like port and starboard sheets on my mizzen, which needed to be sheeted in more, but I think that upper and lower sheets for your larger after sail will be better value for reducing twist. If you were going to be on a long closehauled tack where you needed the very best pointing ability, it would be helpful to have a way of shifting the upper sheet only up to weather - this would give the sole advantage of port and starboard sheets, without the continuous hassle.

After sail: I was thinking of simply adding a panel, keeping P the same, only increasing B a little more than for the fore sail, and going up to seven point sheeting. Even consider adding two panels, with eight sheeted points. This is perfectly possible with upper and lower sheets.

Darren Bos wrote:

I must admit I like the shorter yard of the Weaverbird style sail and am considering making that change. However, reading through the thread I feel like I've missed the point a bit. My understanding of yard angle was that you could decrease the yard angle as you increased the balance on the sail. However, if you have hinged battens you must keep the balance relatively low. Is it just that the higher AR rig used in the Weaverbird style sail is more tolerant to bending the rules around yard length and sail balance?

No, I don't think so. The rules still need to be applied fairly rigorously. I'm not sure what you mean by more tolerant, Darren?  

When I'm designing the upper portion of a rig, some of those rules are:

1. Angle between halyard and mast less than 30 degrees.
2. Halyard attached at centre of yard.
3. Diagonals of upper panels not shortening too much, sending the yard so far aft that it loses contact with the mast when the sail is furled; but shortening enough for the after end of the yard to stay aft of the topping lifts when the sail is furled.
4. Yard angle not so high that it risks getting underneath the topping lifts during the first part of the hoist; but not so low that the balance becomes unacceptably large.

I have to go through a number of iterations and much trial and error before I'm satisfied with what I've got. Thank goodness for CAD, I couldn't do it using a pencil and eraser. But once I've got something that works (and the weaverbird shape is one such), with CAD it can be scaled up or down and I know the geometry will remain valid. (Arne does the same, with the templates for his kind of sail). Any deviation from that geometry means that the whole of the upper portion has to be re-evaluated. Happily, the lower portion is more straightforward, if it simply consists of parallelograms - adding or subtracting one panel doesn't invalidate the design. 

Erik, given the similarity of our boats I've been watching this thread closely. In fact, superimposing your Weaverbird style sails onto the ones I drew based on Arne's master sails and PJR shows pretty similar results (the sails in the drawing are pasted one atop another without any rescaling, although the balance on our masts differs somewhat). 

I must admit I like the shorter yard of the Weaverbird style sail and am considering making that change. However, reading through the thread I feel like I've missed the point a bit. My understanding of yard angle was that you could decrease the yard angle as you increased the balance on the sail. However, if you have hinged battens you must keep the balance relatively low. Is it just that the higher AR rig used in the Weaverbird style sail is more tolerant to bending the rules around yard length and sail balance?

I've run the full breadth of Junk sail styles in my planning. Originally I was convinced a wingsail was right for me (I still dream of them fondly), but eventually settle on the simplicity of the cambered panel rig. However, I did go as far as to work up some hinges with David's advice and some experimentation of my own.  Here is a link to a thread that discusses the hinges and has another link to a video.  If you'd like, I'm happy to ship you one that you could use to make a mold and cast your own in urethane. There are many choices in castable urethane that let you tailor the hinge to whatever you desire in terms of strength and flexibility. I made a plaster mold in an afternoon and cast my first hinge the next day. My hinges should fit your sail without modification as my batten size choice was the same as yours.

It's interesting to see how the process evolves differently for each boat. The sailcloth I chose forces me towards vertically seamed panels, which makes broadseaming and round an obvious choice to produce camber. My foremast position and rake means that hinges aren't practical on the foresail and out of simplicity I doubt I'll make one sail hinged and the other not.  I look forward to seeing your final design.  I'm planning to sail down the California coast in 2018, it would be great to sail the boats together.

Thank you Ueli and Arne!  Good to know I'm not the only one that is using a work-around to find the CE.

David -  I downloaded the DXF file of Weaverbird and used it to tune my drafts of the mizzen and main.  I worked within the constraints that the Freedom has regarding mast spacing and my desire to be able to reach the clew and am getting to an AR of 2.6 for the main and 2.23 for the mizzen.  Any concerns with the former or the planform of the sails in general? 

et al...  based on what I've been told and learned on this forum, I think the current "Weaverbird" profile for the Freedome 40 CC couldn't  could work with camber created either by barrel-shape, shelf-foot or hinges.   Each design has it  advantages, but at present I would like to pursue a combination barrelshape/hinged design, for the following reasons...  The reduced amount of cloth for creating camber through the cut of the sail and the hinges, may help in the batten stagger during reefing, may also fill more easily in lighter winds, and with a 15% overlap, interfere less with the mast.  

Given the size of the larger mizzen at 47 sq meters and batten length of 5 meters, I'm considering 50x3 mm 6061 T8 Aluminum tubing for the boom and battens.  I have a 150x100 by 5mm wall thickness catamaran mast section available for the yard.  Are these appropriately sized?  David - where the hinges engage I can double the wall thickness either on the od or id side of the aluminum battens . This is the current supplier I have in mind - the aluminum tubing comes in 12ft lengths..  They also have similar wall thickness pulltruded fiberglass tubing, but unfortunately those are only 8ft long and (obviously) not as stiff.  Whereas the lighter weight of the aluminum fiberglass is attractive, the lenght may not fit within your hinge spacing for my 5m battens on the mizzen?!  I realize the fiberglass battens would have to be reinforced at the ends with some sort of diagonal cloth.

David - Can the hinges for this size sail(s) still be made of PVC?  Certainly it is one of the cheaper materials. 

OK. I'm am out this weekend for a sailboat race, and some festivities...  Cheers everone,    

Erik