Alinghi experimented with 3Di in the 32nd America’s Cup (they didn’t race with it), in the intervening 5 years, the technology has been refined to the point where it’s now being more widely used for performance sails.
Anyone heard about anything similar being used on RC sails ?
Zvonko Jelacic makes(or did) them. They are causing quite a problem in the IOM class. See this link http://www.iomclass.org/phpBB3/viewtopic.php?t=1662 Or this one http://www.jelacicsailing.com/index.php?page=shop.product_details&flypage=flypage_images.tpl&product_id=66&category_id=15&option=com_virtuemart&Itemid=104
Don
There is a big difference between 3Di sails and what Zvonko is doing. One common trait is the use of heat and pressure, but 3Di sails have a lot more than just the single laminate.
The original question was 3Di sails for RC sails. My answer is that there would be no point in such complex and expensive construction. A 3Di sail starts as a set of single sheet laminates seamed together over a curved airfoil former. But on big boats, the stresses are so great that the laminate would quickly stretch and distort and be ruined. (Not a problem in RC boats as the forces and the material strengths scale differently).
To add the necessary strength to the sails, a series of tapes, each containing many strips of carbon fiber or kevlar, are laid onto the laminiate. The strips are carefully laid down along the high force lines of the sail. More strips (extra weight) are laid where necessary, and fewer (less weight) in the center of the sail where forces are least. Finally, the sail is vacuum bagged and heated, to fuse the layers together.
All the work of laying reenforcing strips are not necessary in RC . They would add weight and stiffness and huge cost. So - ‘No’ - I don’t see 3Di sails in RC sail.
But single or multi panel sails (without reenforcing tapes) heated and stretched over an airfoil are being done now for RC. The issue of legality will depend upon the specific class rules and as this is a new idea may cause some controversy in some classes (as in the IOM class as pointed out by Don).
John
John, I agree with you about the NS patented 3Di sail making technology (not to forget the cost) is far beyond the needs of RC sails however, Zvonko Jelacic’s moulded sails hits the RC sail sweet spot, reading his explanation in the IOM threat link provided by Don on how simple they are to make … is great food for thought !
Cheers Alan
Any comparative tests made ?
ClaudioD
Good question ! …after reading 4 pages of IOM discussion on ruling of moulded sails I wondered the same 
Have sent e-mail off to Jelacic asking that exact question about his 3D monofilm sails compared to panelled sails, will share response when it arrives
other questions:
What is the lifetime of such sail ?
How long can maintain the shape ?
ClaudioD
Info on the web site states:
Advantages of Jelacic 3Dmf sails:
We are still working on better esthetical look of 3Dmf heat moulded sails. If you carefully inspect the sail, you may see small dots and bubbles. This is unwanted production side effect. Dust and air particles are trapped between the sail and the mould and they are causing mentioned imperfections. You may also find small dried water drops because every sail is washed to improve bonding ability.
The disadvantage I see is that you have to make a mold to form the sails. Lets say you go to all the work to make the mold and you test the sails. You then decide that a little fuller in the top might be better. Now you have to start all over. With a seamed sail you pick a different block and make a new one. I can see the advantage for commercial use once you’ve decided on a shape but then you’re stuck with that shape. I guess I’m looking at it from the point of veiw of someone who makes his own sails.
Don
For me seams and battens are producing a more stable sail form like on surf sail.
According to what I see, rigid sail offer better speed/power while the shape is more cornered then a nice curve . Why ?
ClaudioD
I agree about what you think of the surf sails, but I think that relationship between the size of the sail surf, and sail material thickness, allows stretch and take a gradual curve in between the battens, much higher than the to expect a RC sail, which has much higher relative thickness.
I would like to know your opinion.
Greetings.
Hi Alberto ,
For my models I simply stick with what I have, reinforced mylar sheet and multi panel sails, until someone will prove with multiple comparative tests, that the molded sail are better and last longer !
ClaudioD
Still no response to my e-mail
Has anyone experienced or know or anyone who has used Jelacic moulded sails or similar ?
-Thanks “Claudio”
-Hello “Alan” Sorry, I do not understand, if you want to know is if anyone has experienced sailing with sails thermoformed, or if anyone has experienced trying to make them.
-A year ago I did some tests with an Vacuum Forming (Formicator) with a plastic sheet , and I achieved good results, but my Vacuum Forming measures only 30 X 40 cm. and remained a project to build a VacuumForming 50 X 160 cm. but the real project is to make the oven to warm.
-All this was because in my area, heat of 43 degrees with 90% relative humidity make double-sided tape that binds the panels come off easily.
Greetings.
-Thanks “Claudio”
-Hello “Alan” Sorry, I do not understand, if you want to know is if anyone has experienced sailing with sails thermoformed, or if anyone has experienced trying to make them.
-A year ago I did some tests with an Vacuum Forming (Formicator) with a plastic sheet , and I achieved good results, but my Vacuum Forming measures only 30 X 40 cm. and remained a project to build a VacuumForming 50 X 160 cm. but the real project is to make the oven to warm.
-All this was because in my area, heat of 43 degrees with 90% relative humidity make double-sided tape that binds the panels come off easily.
Greetings.
Gidday Alberto, my interest is in experience with using them sailing, always interested in new ideas
can imagine 43 degree’s C would be nightmare for any sails :rolleyes:
Cheers Alan
-Hi again.
-I can understand the reasons that some of you are in favor or disagree with thermo-molded sails.
-But I still think in my old problem. When it’s hot here, (March, April), with temperatures of 43.5 ° C, and humidity of 90%, the panel joints of the IOM sails come off, or at least slip double sided tape .
-From what I’ve been thinking about how to build the molds, and the thermo-forming for sails.
Many greetings.
I have thought about making molded sails. The technology is pretty simple and it would lower the price to make sails as a full suite could be made in a few min by molding. The downside is the cost of the mold and the cost to make changes.
could you not make a very simple and easy mold. use a known naca profile or parabola, ect. like you would use to create a sail block. However… rather than making a sail block. you make one big form, a wing more or less, that is the size and shape of your desired sail. Using plywood, luan, formica, ect.as your skin. this gives you the ability to lay up your material to get the desired shape. The down side, you cannot control chamber, unless you make a new mold. If you have made your Mold/wing larger than your sail. you can move the location of the max camber.
Since I sail many classes. lets say I make one sail mold(wing) the size and shape of my EC12 main. I could, in theory, use this mold on every single sail from my ec12 down to my rg65…Yes??? just modify the sail placement on mold to correspond with the desired max camber location…
When I make a sail(using blocks) it takes maybe an hour to cut the panels and seam them together. Then I have a blank roughly the same as a molded sail. Now all the work starts. Cutting the luff curve, cutting and attaching the luff pockets, cutting and attaching the corner re-inforcements and punching in the corner eyelets. Then putting the numbers and such on. This is where the time comes in. This takes me 3-4 hours I guess. (once I’m in the shop time kinda stops) So the time saving for molded sails doesn’t seem that great to me and any time saved is more than offset by the time to develop and build the mold. Again this is from someone who isn’t making sails commercially.
Don