Sailmaking

[Andy K]

The basic measurements are pretty straightforward.
But does anyone have any good ideas about creating a bit of shape.
It's one thing putting a curve in the luff of the mainsail, but with only five attachment points to the mast, I don't really see how the curved luff would work.
With a stiff mylar material, there would not be any give, with a softer material, the leech will simply fall away.
The drawings for the jibs all show a straight luff. If the luff wire was held very close in the tabling and a curve introduced, would that encourage a bit of shape?
Clearly, from the above, I have never made a set of sails in my life!
It's one thing thinking its a flat bit of material, it's another actually getting a suitable material and doing something about it.
I still intend to have a go, but any thoughts might help to cast a bit of light on the problem.

[John Tushingham]

Hi Andy

The sail measurements and rules are intended to make it easy for anyone to have a go at sailmaking and come away with a competitive suit of sails. The material I use for the A & B suits is TriSpi 40, for the C it's TriSpi 54. This material is available in short lengths from Peter Wiles at PJ Sails. For the mainsail luff curve I suggest you try about 4mm max curve positioned about two-thirds of the way up the luff, this should give you a good shape, then you can fine tune it if you feel it needs more or less fullness. The jib luff should be straight, the rules will be altered to make that clear. The natural sag of the jib luff in use will push shape into the sail and give you a surprisingly good looking shape.
Keep the mainsail ties to the mast quite loose, about a 2-3mm gap between mast and sail, this will allow the sail to soak up any excess mast bend in gusts without introduce big diagonal creases. The only real downside of the flat panel sail is the inability to get any real fullness into the mainsail head, but I feel that's a small price to pay and if you're racing your DF in the restricted class it's the same for everyone.

I hope that info gives you the confidence to have a go at your own sails. The fleet racing at West Lancs every fortnight includes quite a few home made sails and I have to say that they all look good!

John Tushingham

[arjan ned 67]

Hi John,

If I understand right, the rules for making Jib will be change?
The luff must be straight and may not be curved?
If that is right, I've seen several sails from also known sailmakers with a curved luff.

Will they be grandfathered or banned and they where a waist of money?

Arjan

[Matt Riley]

Hi Arjan

It would be a clarification of the rule for the jib rather than a change. From section H of the rules and the sail measurement diagram I would say it is fairly clear that the jib luff should be a straight line rather than a curve.

Curved Jib luffs would probably fall foul of Rule A.4 as well.

Cheers
Matt

[arjan ned 67]

Hi Matt,

The Ask for Clarification isn't new.
More sailors and also sailmakers interpretated the rules as it is possible to make a curved luff, as long as the measurements AC and BE are correct.
For me, I make my own DF sails, its not a big problem, but if I have sails from some sailmakers, costs 35 GBP a set, I'm not happy with this clarification if that means to invest in 3 new Jibs.
The Graphite jibs are straight, thats right, but that were the only one I have seen with straight luff.

What A4 had to deal with, I really don't understand, only that excisting sails with curved luff may use after clarification (to kept cost low).
To find an advantage, no, its only what we did always with our luff.

(other topic with question about luff)
https://groups.google.com/forum/#!category-topic/rg-65-uk/dragon-force/xb4QWhsjjYs

the topic about tabling the luff, I can't find, but I know that I ask something about it and also mention the curved luff.

[Matt Riley]

Hi Arjan

I have looked at the other thread and Barrie was chasing John for confirmation - which has been supplied above - the the jib luff should be straight.

Personally I would have taken the fact that the jib luff is marked as a straight line on the rig measurement diagram and is straight on the manufacturers sails would have been enough for people to realize that any replacement sails would need to be the same - the DF is a restricted class after all.

Which was why I mentioned rule A4 and "not seek to gain a performance advantage by manipulation of the wording through translation or other means"

If sailmakers are making DF jibs with curved luffs then they will need to discuss with Mark/Mike/John if they are considered legal.

Cheers
Matt

[John Tushingham]

Rule Clarification.

The Jib Luff between points A & C should be a straight line as shown in the sail diagram (Diagram 1). A new version of the rules (version 1.3) will soon be published on the dragonforce65.com website to clarify this. The only two curves to sail edges allowed are to the Mainsail Luff and Mainsail Foot, both these are defined in the rules by either cross width measurements (mainsail luff) or by a fixed point (M) and fair curve for the foot. A decision will need to be made about existing sails that have a curved luff as to their legality, should they be 'grandfathered' or banned! A curved Jib luff is not mentioned as a 'permitted change' in the rules and the diagram clearly shows it as a straight line, so my opinion is that the rules are clear on that point, but it will get better defined in V1.3 of the rules.

Arjan, Your earlier question about jib luff tabs in place of one, full length jib luff pocket has already been answered by Rule H.5. Again, this was done to keep the boat as close to factory spec as possible. Some people think tabs are better, but if we all have the same - it doesn't matter!

Cheers

John Tushingham

 

[arjan ned 67]

Thanks John,

I mention only that discussion of luff tabling, because there was also mention the curved Luff or I tried to, by asking one Lufftabling or like the MM in parts, which is much easier to get on a curved luff.
I didn't ask again, it was clear to me, and have also make that more clear in the dutch translation.

I know more drawings of sailplans, there the luff is straight, the sails curved.
The function of that diagram is only to show where the measurementpoint are situated.

But fine, now we know it has to be straight,

cheers

Arjan

[arjan ned 67]

@Matt,

The manufacturer sails are always into the rules,

If I have a look to these sails, they are al different, the first one I saw was curved,
some are straight (more or less) but have some with a negativ curved luff.

But again, I will not take manufacturere sails as a reference for anything if there is a rule, you can read.

[Aus Crankster]

Hi, I'm putting my DF together and want to make a set of sails for it. I have a couple of quick questions.

Are people using 'sticky back' or self adhesive dacron for the patches and tabling?

I note that the jib can use a luff wire. Is this held securely by the tabling or is the sail free to move on it?

What material are others using for the battens?

Are there any other sailmaking tips that it would be handy to know before I begin cutting :) ?

[Barrie Norman]

The corners are self adhesive Dacron, I use 20mm luff tape with 6mm double sided tape for the jib tabling the luff wire must be free to move, luff tape and self adhesive bat tern material is available in the UK from Sails Etc not rue about availability in Australia.

[Aus Crankster]

Thanks for this information Barrie. 

In the class rules, the main is shown with the option of some main luff curve. What rule of thumb or measurements are suggested here ?

[Barrie Norman]

That is a difficult one to answer and most sailmakers will differ on their opinions of the shape of the main luff, but as a ball park the max measurement should be about 3mm and 2/3 of the way up both curves should return to the zero point making the top part of the curve tighter, again draw it out on paper first, and remember that you can't add area to the main sail but you can take it away so the curve should be inside of the original sail area.

Barrie

[Aus Crankster]

Again, thank you Barrie. I'm just drawing up a template for sails for my new DF. As the ultimate performance at this point is mostly academic, I'm using it as a learning experience :)

Cheers