Hi All

No worries then. I am a little confused though, the sail would fit into F16 specs, so we will, if approved, have adopted a F16 mainsail? Or is it the fact that it still has measurement restrictions?

Matt

Matt,

I think this is hard to say.

We may find that sails compliant to the proposed rules are F16 compliant but from the rules themselfs this may not be garanteed.

F16 rules on the Mainsail are :

max area including mast = 15.0 sq. mtr
max luff length = 8.10 mtr. (when downhauled)

So F16 class rules will not easily disallow a given mainsail design.

However, it may be possible that the proposed rules still allow a flap at the bottom of the Taipan sail which puts its total area passed 15.0 sq. mtr. Rolf made a rought estimate of the area but did he envision all the possible ways to maximize the mainsail area ? Maybe there are other loop holes that do conflict with either F16 rule. The limits on width and leech/foot lengths do not in themselfs limit the total area of the sail to max 15.0 mtr.

I think the proposed class rules do limit the max luff length to the same level as the F16 rules have set it. So no problem there.


Additionally, the issue raised by Paul is that the much more detailed Taipan rules as proposed may in fact conflict with existing (or future) F16 mainsail designs of some sailmakers. In effect these sailmakes will always have to check their designs against two different sets of rules when the performance determining features are identical. I have understood this to refer to a situation where the limits are needlessly confusing for sailmakers.


The way I understand it is that only two situations can result from the proposed rules :

-1- The F16 sails are not necessarily Taipan compliant
-2- The Taipan sails are not necessarily F16 compliant

Either way the sailmakers are pretty much required to develop two different mainsail designs for effectively the same mast section and comparable boats.

I share the opinion that this is not really handy to both sailmakers and sailors. It can only lead to higher prices (as more work is involved) for zero differences in performance. Also it will hamper the second hand market in these items.


Wouter

Have a look at Rolf's post (and Wouter's follow-up). A conformant sail will probably fit inside F16, but it is likely that a sail fully optimised for these specs will not be fully optimised for F16. The problem is that the proposed rules (like the F16 rules) do not describe a particular sail, they describe a set of restrictions within which a sailmaker can create a sail. From what Rolf and Wouter say, it seems likely that a sail fitting the new Taipan rules would also fit within the F16 rules, but I think it's rather less likely that the reverse would be true.

The Taipan rules are more restrictive than the F16 ones, and I only hope that the reason they are considering a different ruleset is because they believe that it will lead to less variation in sails and thus performance (a reasonable aim in a OD class), rather than out of a desire to be different from F16 due to historical differences...

Paul

It's interesting that there is talk of "common" sail development in a formula/development class forum. I thought the whole point of formula/development classes was so that we were able to try different design options that suited us. This talk of taking "a lot of time and effort to optimise a sail" sounds like an argument against formula/development classes and counter-intuitive to the formula/development ethos.

In my opinion, what a one design class does to their own class rules is their perogative. Who knows, they might've decided that they are just a little off the pace with "optimised" F16's upwind and the simplest way to catch up is to just add a little extra mainsail to be competitive. Perfectly reasonable in my opinion and good for the F16 class with more potential numbers. Good for the Taipan class as their boats are now (potentially) dual compliant (with kite).

Everyone should be happy, both classes can now be strengthened.

Okay- All this talk of new Taipan 4.9 mainsails for the AUSSIE class is fine BUT- What is that going to do for the Non-Aussie Taipan 4.9's??? <img src="http://www.catsailor.com/forums/images/graemlins/confused.gif" alt="" /> Since all Taipan 4.9's to date (to my knowledge) have followed a single set of OD rules if the Aussie Taipan Class votes to change "their" rules does it effectively (or completely and totally) change "the" OD rules for every Taipan on the planet?? If so, then I think every Taipan 4.9 owner on the planet should be entitled to vote, including all the ones in the US, EU, Asia, etc.!! <img src="http://www.catsailor.com/forums/images/graemlins/shocked.gif" alt="" />
And if the "Aussie" rules can be changed by just bringing it up and voting on with a 2/3rds majority which won't change "the" rules or "our" rules then I propose that all the Non-Aussie Taipan 4.9 owners hold our own vote to change both the Mainsail (and jib?) to be F16 compliant. <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" /> Would sure allow me to save money and sail as either 4.9 OD or F16 much easier/cheaper.
<img src="http://www.catsailor.com/forums/images/graemlins/cool.gif" alt="" />
Kirt

I think you will find that it only relates to the Australian National Taipan Class. That means that only members in good standing with that association should have the right to vote on this change. If other associations around the world choose to have their rules based on the Australian model then that is up to them. I see no reason why international sailors should vote on Australian Class rules. If they don't like them, then they always have the option of adopting any rules they like in their country. They always have the opportunity to join the Australian Association if they want their vote cast.

Tiger Mike

I was just asking to clarify what would happen if a "new rig" T4.9 with kite turned up to a F16 event.

Maybe that will never happen.. But if it did..

Its a great way to further disenfranchise the owners that are not in Australia, but the Taipan class in Aust will not be too worried about the OS boats, so you shouldn't be too worried about them....

If I had a taipan and was not in Australia, then I would be doing whatever I wanted to the boat, Oh hang on I did that already to the 5.7 and I live in Aust!!

I don't think the new mainsail will get passed as the class seems to have settled into a comfortable level and the current owners seem happy with what they have.

Hi all,

I am sure some may have thought of this but I will post it any way.

The major problem with this proposed change to Mainsail as far as F16 compliance is concerned, is that they are not changing the Jib to the smaller F16 jib at the same time, which means that the overall sail area will be greater than that currently allowed by F16. <img src="http://www.catsailor.com/forums/images/graemlins/frown.gif" alt="" />

This I would imagine makes Grandfathering more difficult. It would certainly make Taipans competing in F16 events in OZ difficult, but I would imagine this problem would be the furthest thing from their minds.

This is unlikely however as most of the talk I have heard has been negative, except the big cat rig guys that used the sail and the few Taipans that sail as F16 most of the time. but they are in the minority. <img src="http://www.catsailor.com/forums/images/graemlins/frown.gif" alt="" />

No doubt I may hear some more at Forster next week.

Regards Gary. <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />

I dont mind if the T 4.9s do or dont.
What I am interested in is what happens if they do?
What does it mean to the F16s if one turns up. Will they still be grandfathered?

Hope the T4.9s fair well in their choice and all the best for future success for the class.

regards
Stewart

Stewart-
I believe it is up to the Aus F16 representative to make this determination for Aus. For the US it would be my contention that a "stock" 4.9 showing up to race against other F16's with such a sail would be allowed to as a cat rig with main only but not as a sloop with the large (ie original) jib. If the boat had a F16 (ie smaller self-tacking) jib then it would be "legal" IMO. It would be interesting to see if the larger, tramp mounted block jib is any faster than a self-tacker equipped jib F16 with both running comparable spinnakers and on a windward-leeward fairly short course I'm not at all sure it would be. In a distance or long race and under certain conditions perhaps and without spinnakers it might prove to be quicker.

Kirt

Kirt,
What you say makes a lot of sense however the advantage of the bigger jib would probably only be evident on triangle courses and distance racing.
Regards,
Phill

IMHO if there is a rule in the book, it should be followed. Especially if it is such a basic thing like motor size! If the rule is wrong or redundant then change it but while it is there it should be followed.

Tiger Mike

The Tornado guys I have spoken to say the larger jib they got improved up wind performance hugely. How do the two size differences compare?
Is the Tornado bigger in a luff length as apposed to the Taipan being bigger in a foot sense?
I ask this as I am interested what to decide on for my wing project.

The alteration in sailplan for the Tornado in 2000 was a larger square top mainsail, spi and a jib with longer luff. I dont think the 'new' Tornado jib is much larger than the old one. One interesting thing they found during the test event at Quiberon was that the old-rig Tornado was faster upwind than the "new" rig. Even with the added power of larger sailarea and double trapeze, the old rig was very effecient, well known and did not have the extra weight/drag the spi-gear added. So if your Tornado friends say that their upwind performance has improved hugely with the new rig, something must either have been wrong with their old setup, or the new-rig saildesigns have improved since the test event (which is very possible).
A longer luff (and aspect ratio) is more effecient then a shorter luff, which means better speed in most conditions. When overpowered and especially on a reach, a shorter luff but more area (lower aspect ratio) can be faster.
If I could choose, I would choose high-aspect ratio any day, as you can then install a selftacker. A selftacking jib makes all the difference upwind singlehanded (not legal when racing F-16) and downwind under spi in any configuration.

For more information about the ISAF evaluation event, which is good reading: http://old.cruisingworld.com/2000/03/isaf1.html

The tornado jib before and after the 2000 change is the same in overall area.

Source www.texelrating.org

Tornado classis jib area = 5.20 sq. mtr. (with luff length = 5.62 mtr)
Tornado (upgraded) jib area = 5.22 sq. mtr. (with luff length = 5.87 mtr)

The luff lengths don't seem to differ that must either.

So I agree with Rolf here; the guys you spoke to must have misunderstood the jib change,

Wouter

I am pretty sure the luff lenght has increased 1/2 meter.....There must be a physical stop 500mm below the bridle and the jibs go all the way down to the pole (which most use as the physical stop). We did not change the lenght of the jib halyard wire strop or the hight of the locking mechanism. We did increase the length of the fore stay though, to enable more mast rake which would have raised the jib further.

I can not comment on weather the jib made much if any speed difference upwind as we went from classic rig, straight to sports rig with self taker and square top. I will say that the self tacker is a LOT slower off the breeze on a 2 sail reach..... With no barber haulers, you could not set the jib properly and it was pretty mutch useless.

One plus though with the self tacker is that due to them very rearly flogging, its competitive life has increased dramaticaly.

It is interesting eh.. You can only take waht people say at face value and these guys were full of the new jib.
This is why I am asking around.. I have learned not to believe the first thing I hear, even if the boat looks flash and the talk is confident.
What you guys say makes snese though because from what I understand it is the slot afect that makes the power so aftger that is is only the extra draft of the genoa. So why are AC jibs so big in the foot? Understanding this stuff is like alchemy! : )

I believe the new jib set up contributes overall to a faster package around the course. Don't think it is quicker up wind (except for tacks), hard to tell if it is slower. Off the breeze though, the jib is insignificant and not having to worry about it gives you more time to concentrate on kite trim and manouvers..... ie faster around the cans.

The new T is fully optimised for windward / leeward racing. No longer suited to 2 sail reaches where it is now quiet a bit slower, however no longer the boats intention with the new course formats.

How is the T scene in NZ..... Worlds coming up are exciting. May buy another boat or Charter a T for them.

I expect the AC boats are as they are becouse of their rules framework and speed range.

The slot effect is.. pretty much a myth. The jib is so very effective becouse it works in the updraft the main creates. It is not a good thing to close the slot, but that is not the key to the sloop rigs efficency. The airstream is 'bent' before it hits your sails, whatever kind of rig you have (I'll not go into the physics behind why it is bending before it makes contact with the sales, but think about your bow-waves and how they look at low speed). If you remove the jib and sail uni, the airstream still bends before it hits the mast, creating an pressure area just in front of the mast and over the leeward side of the sail. When you put a small sail in front and to leeward of your mainsail, it works in an airstream already influenced by the mainsail, taking advantage of this. That is why the jib is so effective pr. surface area compared to the main, and why a good jib is so important.

For a much better explanation than mine, here is what the late Arvel Gentry had to say about the "slot effect": http://www.arvelgentry.com/magaz/Another_Look_at_Slot_Effect.pdf