Claudio’s Gadget 2.0:
@ Tony
What are the dimensions and the materials of the beams in your CG 2.0 Wolfgang?
I used pine 90x18 for the fixed beam and 12x18 for the flex, its just what I had lying around. Problem is the double-sided tape is lifting the grain of the wood, so I’ll be going back to Al.
I do like Swiftsure’s double-sided idea, I will try that instead.
So far the couple of sails I made with the Modified GZ (Gadget 2.0) have had way too little curve in the top seam eg.
I’m still experimenting with the same sail - IOM B jib and I used the CG wedge graph as a guide, just doubled the shim for the single spacer rquired for the GZ.
Foot set at 5.8%, bottom seam (227mm) aiming for 7.5% (shim 1.0mm) and top seam (112) 8.0% (shim 0.6 mm) I got the following:
When I doubled the shims to 2.0mm and 1.2mm I got:
When I tripled I got:
And on the trippled version I added extra to the foot… so maybe the Claudio gadget wedge graph (as suggested above) is not going to work out.
Having said that, the florist wrap material I am using is quite flimsy and prone to stretch a little and I did pull one sail apart to make another so that may have made some of the analysis a bit inaccurate.
I will make a double-sided GZ/CG and trial and error to get my 7.5% and 8.0%.
Hi Tony,
The flexible beam is 11 x 11 , a U-profile, must be some plastic like PVC. It’s quite flexible near the bolt and was ok with Claudio’s Gadget so far.
The fixed beam is 20 x 11, aluminum.
Below is the latest analysis. Foot measured at about 20mm (9.4%).
Aiming for 7.5% for the middle seam and 8 for the top.
Using the Double-sided Claudio Gurkenzange Gadget (DSCGG, yes its time to coin a new name for this critter) the shim widths I used wer: 3mm for the middle and 2.5mm for the top.
I am just not sure now whether the sail has the aimed for seam camber (above) and because of the twist its is being flattened out or whether its still not enough gap when I am setting the seams.
It looks ok, considering the flimsy material, and apart from the top seam aft camber slightly more than the forward section, the numbers look ok too.
PS Note, I used a feeler gauge as the shim spacer for the DSCGG which is Aluminium (12mm, 1.7mm) and slightly too stiff. I’ll add a screw to ‘wind’ it apart.
I noticed something similar, I’ll post later. 7.5%/8.0%/9.4% would be nicer.
So the Gurkenzange needs more bending than the c-gadget (I had something like this in my mind but didn’t make any notices some years ago).
With the DSCGG, do you bend both beams?
next one 
I need new sails for my tornado, but I’m not yet decided which tool I should use.
The old sails were made with the gurkenzange, but unfortunatly I didn’t notice what I have done 
So first of all I liked to know what’s the gurken sail is like, so I measured the old sail.
It’s a bit worn out and the draftposition(%) is a bit undecided
So for the new sail I used Ben Morris draft calculation (I filled out the yellow cells and got the light blue ones to build the draft into the seams).
With Claudio’s Graph I’ve got the multiplier factor and the number of plates I should use. So far everything as same as with Claudio’s Gadget.
But this time I wanted to use the gurkenzange 2.0 which should give a flatter downwash zone near the leech than Claudio’s Gadget.
Tony mentioned that he had to bend the gurkenzange 2 or 3 times more than the Claudio’s gadget.
So my first idea was to use Claudio’s draft but to place the plates not at the leech but at 50% chord lenght.
The first 50% from luff to center would be bended parabolic by the plates and the second 50% from center to the leech contour should be linear.
I wanted to see how much draft would go into the sail, where the max draft is located and what’s the downwash zone like.
So this is what I’ve got:
(click on the attachement to have a better view)
(don’t use dark grey sail cloth, you won’t get decent pictures and at the pond it’s like camouflage)
With this sail I had some problems to measure it because it has much leech roach and no battens yet.
It was difficult to get a decent entry angle and to see the max draft position. So I measured it from both sides.
So starting with 6% sag at the foot I got only 5.6% draft at the first seam. And the seams following above don’t have the desired max draft%.
But at the second 50% chord lenght from center to the leech contour the sail is nearly flat.
(I tried something similar with other main sails using Claudio’s Gadget but I was’nt sure so far if it would work that way.)
(to be continued)
Today I met a real sailmaker. This guy has been sailing for years and makes big sails for a living. He also is a very good IOM sailor and makes sails for some very good skippers. He generously allowed me to pick his brain a bit with the ideas we have been discussing. We talked about the different gadgets and the pros and cons, I’ll come back to that.
First let me divulge some the tips he gave me. He likes to sail in a mode of bearing away slightly with increased speed rather than trying to point too high because he says these little boats need the speed to punch through the chop.
So his prescription: The sails need to be much fuller than the 7,8,9% I been thinking of, closer 10-12%. Just as important, for the jib the maximum camber needs to be nearer to the luff than on the main. His suggestion is Jib 32% for the top seam and 36% for the bottom seam. For a (3 seam) main 40% at the top, 42.5 for the middle and 45 for the bottom. He actually cuts in a slightly concave luff curve (1-2mm) on the jib to counter the tendency of the forstay to sag slightly.
I suppose for someone who preferred to point higher as their mode of sailing the sails could be ever so slightly flatter.
As I said he makes sails for a living… I am going to follow his advice. He suggested that the Claudio gadget (despite its short-comings) is the better tool because you can precisely set the maximum camber point, the DSCGG would be ok for making mains, having the average max. camber around 45%, but no good for jibs - so I am going to abandon the DSCCG. So I will continue to experiment with the Claudio gadget to acheive the above sail profiles with the florist wrap and post the results.
By the way he uses the big boat software and computer cutter to make the panels then tapes his seams together more or less by eye, in one smoothly decreasing arc! I guess one you’ve made a few hundred and sailed them too you are allowed.
Just to answer your question from above Wolfgang, yes both beams were bent equally. I still can’t quite work out why the shims need to be that much greater than with the gadget…
Hi Tony,
thanks for your report 
a good point, while having chops, I usually have to set up a quite different trimm.
With the IOM, I agree
these 30er% jibs are much more tolerant to bad steering or sheeting or during sailing in choppy water. But you loose pointing ability.
I would like to have some concave luff curve, but I’m not able to build a concave luff pocket 
I agree
Ben Morris showed some nice curves generated by bending a bar:
from
http://www.stirling.saradioyachting.org.au/saildesign/claudiotool.htm
So regarding C-Gadget and gurkenzange:
[ul]
[li]with the C-Gadget you have two parabolas on each side of the bolt, one on the left side to the luff and one on the other side to the leech
[/li][li]with the gurkenzange you only have one parabola from luff to leech
[/li][li]with the C-Gadget you have more or less two 1/2 chord lenghts, so two ‘heavy’ bending zones near the bolt
[/li][li]with the gurkenzange you have only one bending zone near the bolt and the chord between max draft and leech contour is far away from the bolt
[/li][/ul]
So my next idea was to use claudio’s graph and two gurkenzangen and bend both upper and lower panels and stick both bended panels together.
And in another step I wanted to increase the wedges.
Well, in the end, both panels didn’ stick together but remained at the gurkenzangen, so stopped further tests. :tand:
The main sail for my tornado cat looks like a fat-head sail,
so where is the leech and where is the leech roach and where should I place the plates at Claudio’s Gadget?
Placing the plates at the leech contour I often noticed that the leech roach at Regina’s main sail was to curvy.
The leech roach between the leech (straight line between the grommets at head and clew) and the leech contour wasn’t flat enough.
So I placed the plates at the leech and not at the leech contour and took the reduced chord lenght into account.
(just as I did it with Regina’s main sails)
With the draft determination by Ben Morris:
and the multiplier factors by Claudio’s graph and the reduced chord lenght I got this main sail:
data:
[video=youtube_share;0a_e_tPmzHQ]http://youtu.be/0a_e_tPmzHQ[/video]
(This dark grey fat-head sail has no reinforcements besides the grommets and no battens!
maybe it would need some better luff curve)
OK, with more leech roach the max draft position is wandering towards luff, but this makes the sail more tolerant in the sail’s upper region.
Real nice images of flying the hull there Wolfgang. Reminds me of sailing on the Nacra 5.8.
The latest sail I made was with the C. Gadget. Wanted: top seam camber 12% and max camber at 32% from luff, bottom seam 10% and 36% from luff. Shim widths calculated from the camber graph.
I measured: top seam 8.5% and 34% from luff, bottom seam 8.7% and 37% from luff. Still flatter than I wanted.
The flexible beam on my C.Gadget is 10mm C section aluminium, it might be a bit stiff for these bends. It feels close to becoming permanantly bent. Might have to find some 10mm plastic.
The top seam wouldn’t sit right (flimsy florist plasticstretched a bit I think) so I extrapolated the curve.
Thanks Tony!
I got into shallow water, so I had to cant the keel :smilebig:
Down at the lake yesterday one of the top sailors had some new IOM B-Rig sails, the jib had a lot of camber and the max camber was quite close to the luff. Very similar to the specs I was aiming for above: snip…
…top seam camber 12% and max camber at 32% from luff, bottom seam 10% and 36% from luff.
Maybe even more camber than that :magnify:
The first attempts with the gurkenzange I tried with a aluminum u-profile but I wasn’t very lucky with it so I tried the plastic profile for the flexible beam.
And now with the Claudio Gadget and Ben Morris’ draft sheet I usually get what I want
Did you try a cross check with something like this?
http://www.rcsailing.net/forum1/showthread.php?3110-sailmaking&p=70011#post70011
Got some damage at the new main during the last test drive (I didn’t handle the mast carefully and opened a seam at the luff).
Anyway, I wanted to rebuild another main with more draft, so every seam should get +1% draft:
Well, hit the marks within +/- 1% 
So I spend some time with ‘hobby-horsing’
(I have to say, it’s not a hobie!)
Nice video.
Can you post some close up photos of hull, sheeting arrangement and hull shapes on the “Multihull” section of the forum, along with some size specifications of hull length, beam, mast height, weight, etc. please? It appears to be well balanced.
Thanks in advance. Dick
Thanks Dick!
It’s my first RC-sailboat I got back in 1975, so it was a loooong way up to here.
More a vintage platform, but in the last four years I tried a refit with rig, sail servos and now with new sails. I’ll try a post at the MH-forum.
My apologies for the ‘gratuitous bump’ of this thread Wolfgang but I was wondering what that sailcloth you used was called?
Although progress on my J has been non existent over recent months I’ve reached the stage where I need to start thinking about sails & rig to establish sheeting positions etc and rather liked the look of the material you’ve used for your multi-hull mainsail.
Cheers,
Row
Hi Row,
yes this is the best thread, I’ve read ever. I have learned a lot! I think 
The sail is made of lightweight cloth (icarex, polyester ripstop material, 31g/m²).
http://www.drachenshop.de/product_info.php?products_id=291
It shows you immediately what’s going on at the pond at light wind conditions.
And what’s going wrong while building a sail
There a many ripstop materials available, most of them are nylon, which is more stretchy especially when wet. I use only polyester ripstop, known as icarex.
They say, icarex is only for light wind conditions, so this multihull sail was a first try to get some camber in the sails. I thought I would have to rebuild it with some mylar cloth. But until now I feel no need to rebuild it.
The weak spot are the seams, you may get some ‘micro’ wrinkles at the seams of the panelled sails.
This may happen when you attach the double sided tape at the seams with some stress.
you may notice these wrinkles at these pictures:
These are some older pictures from my long keeler. (sails made with the ‘gurkenzange’) Nowadays I choose brighter colours for my sails. At the regattas I usually have one of the smaller boats, so these brighter colours are better for visibility in a field with +25 yachts
Can’t wait to see some progress with your J Class Enterprise!
Next on my building list is the Ranger.
best regards
Wolfgang