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Does anybody know what the idea behind the design is?

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More sail area higher up to get the hull out in lighter winds. Hobie offer this type of sail on the Tiger for 2005.

Paul

Rolf,
As pointed out Hobie put this type of design on their Tiger and I'm told it really works well for them. Most of the F18s are moving in this direction now.
It is F16 legal, the area for the larger head comes out of the leach producing a fairly straight leach on the sail. If you have a look at an F16 sail with a smaller head you will notice the leach has much more of a round. Make it straight and you have all this extra sail area that you can put in the head.

Regards,
Phill

Ok, thank you. Must be nice in low wind conditions, but I look forward to hearing how it behaves in stronger wind and how they handle it

If the area in the top comes from straigthening the leach curve, the foot must be shorter to compensate? This might be a good thing if you are looking for power, as the bottom of a sloop sail is quite flat to compensate for the jib's backwind. Hmm, I mostly sail in low wind conditions (class illegal for me, but anyway)..

Is the F-16's first to market on this, or was the F-18's there first?

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Not an optical illusion, I just think the cloth is double thickness there as there is a join I think

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Sorry Simon, can't see that the sail would be double thickness there. Seams are typically only 1cm of overlapped cloth. That 4th batten area is clearly of the order of 5-6cm. The batten pocket would account for around 4cm. If there is a seam above or below the pocket that might explain the appearance (a coincident seam) but it is still a shame as it does spoil the look of the sail.

Surely those are just black painted or anodised beams Wouter? I can't see the justification for the cost of suitable carbon beams. It's not as if it hasn't already been demonstrated that an F16 can be built down to weight without compromising structure.

It does indeed look like a batten pocket laid under a horizontal seam between panels.

The glue used for laminates today are often 25mm and upwards wide. Its strong enough to eliminate stitching in smaller sails, so it might be something like that we see..

John,

Scooby is correct. If you dont have a full 50mm overlap in the cloth at the only horizontal seam the sail will not last long at all. Trust me I can tell you by experience.!!! Mylar sails can take some high loads depending on the fibre configuration, but stitching across the load of the panel will just pull through the fabric with out the assistance of some sail number ( or sticky back) to help hold the mylar together. If you look at some sail with a similar panel layout you will notice up to 5 runs of stitching just to keep the seam together.!!

While on this subject it will be interesting to see how many sailmakers will succeeed with the new contender "Maxx" fabric, as all seams will be cross cut & subject to high loads. Rolfe may be able to give all an idea on how he has approached this issue.??

A fellow had one made here ( a cross cut mylar sail with contender maxx febric)in Adelaide by a reputable sailmaker & against my advice he did not treat the cross seams with respect & the sail became flatter & flatter each time he sailed as the tapering in the seams were "straightening out" & the sail was a board & inverting in meduium to high winds. Needless to say the sail was only used 5 - 10 times & now useless.



Regards

Marcus

No experience with it yet. Hoisted our Maxx cloth sail first time on friday, but still have to install grommets for the battens, stretch and secure the bolt-rope and some other small stuff. If we can use it the coming week, I'll be pleased.
Marcus: I'll send you some photos once it's finished.


We used 25mm overlap between panels (cross cut layout), 25mm 3M special basting tape/glue for laminate construction and two rows of three stage zig-zag stitching. We also double folded all hems, and did some special reinforcing at the luff to take downhaul loads. Batten pockets are installed with 25mm glue and a single zig-zag seam over the panel seams (not optimum placement, but close enough for this try).
We hope this will be enough to hold the panels in position, but time will show.. I'll be sure to let you know if we have catastrophic results.


Macca have some practical experience with his Maxx sails now, so perhaps he could say something about it. Looking at the pictures he posted earlier in the 5.7 thread, it seems like they did a sandwich construction at panel seams integrating batten pockets, and further sandwiching at reinforcements etc. Interestingly enough, the reinforcement along the luff seem to be glued on..

Ref: http://www.catsailor.com/bb_files/49474-DSCF0441x.JPG
Ref: 5.7 Thread

Okay Marcus, I see what you are getting at.
Doesn't overlapping the cloth to such an extent create an anomaly in the stretch and flex characteristics of the sail though? I know that there is a batten at this point. So does that mean that this batten would need to be slightly lighter than would normally be used?
After all, you have now got one point in the sail which has two layers of cloth glued and stitched together (possibly with some sort of film or re-inforcing) plus a 40mm wide batten pocket stitched top and bottom and a batten all at a single point on the sail. Is this not an excessively 'hard' spot in an otherwise (relatively) flexible sail?

(as if modern laminate sails can be described as flexible )

I understand the principle of modern sail design with current cloths and the use of load paths, but looking at this F16 sail that 4th batten area just looks sort of disjointed and uncomfortable. The seams above and below the batten don't even quite line up?

As far as I know both the A-cat class and the F18's went down this road before us. That and more more experimental boats/classes. Maybe the new Tornado also.

It seems to be the latest trend. I personally like the looks of a straighter leech over my own curved one but Agent orange is pushing it.

But indeed, the large heads seem to be very competitive in teh F18 class. Powers them up in the light stuff and flicks off in the rought stuff.

However, you'll need to do alot of fine-tuning while sailing. I have the second generation mainsail. Meaning entlarge squaretop with respect to the standard Taipan and I notice that in changing winds I must trim, with the mainsheet continiously. It works very well but you have to do it otherwise you're either hooking or throwing away power.

Mind you I'm really beginning to get addited to this lively feel. I wrote I wrote this down a couple of times before. When I switch boats I always have to remind myself to not get frustrated when this other boat doesn't react as my own one.

We'll just have to see where this all ends up. For now there is alot of activity behind the scene with several homebuilders who by definition try out (new) stuff


Wouter

Asian boat has a twin several 1000's miles away

Because here in sunny Netherlands




Wouter