Guys,





I think I am correct in saying that the spinnaker size chosen for the F16HP sloop was chosen so that it would compete on equal terms with the F18's - ok, this is a good idea.





The same spinnaker used on a solo F16HP enables it to compete on an equal basis with A-class. Is this useful? I feel perhaps it would be better if the spinnaker size was increased for the single handed F16HP so that it too can compete on elapsed time with the F18 and of course then also the F16HP sloop.



Is this possible? What is the feeling amongst the rest of the group? Are we restricting the performance of the solo F16 unneccessarily?



The F18 class is gaining momentum in Australia. I'm not interested in sailing them because I love my lightweight cat rigged Taipan 4.9. I would however like to be able to put a spi on my boat and race them on equal terms. I have only one A-class to race against.



Berthos.

>>Are we knobbling the Single Handed F16HP??



Most certainly not !





>>I think I am correct in saying that the spinnaker size chosen for the F16HP sloop was chosen so that it would compete on equal terms with the F18's - ok, this is a good idea.





That is correct. The single hander spi size was directly set by this choice as we decided to make an platform that could do all with the same hardware. No addition sails needed or different rigs for different modes.





>>The same spinnaker used on a solo F16HP enables it to compete on an equal basis with A-class. Is this useful?



Well, this is more the result of the Equal-to-F18 choice in combination with the "all with the same hardware" choice than a concious decision on it's own.



It just turned out this way. We were a little bit lucky here.





>>I feel perhaps it would be better if the spinnaker size was increased for the single handed F16HP so that it too can compete on elapsed time with the F18 and of course then also the F16HP sloop.





Well actually both the Texel and ISAF 1-mode ratings are faster than both the F18 class and the F16HP sloop class. So in effect the F16 spi needs to become smaller in order to achieve equality to these classes when single handing.



And ofcourse you may do that as the spi size in the rules is only a limitation on the maximum size of the spi.



Personally I think that the 2 to 3 points rating different in favour of the 1-up F16 is about right to correct out over the extra difficulty sailing such a boat solo. Remember that your sets and douces will be considerable slower and that in the stronger winds you have a less favourable righting moment to drag ratio.



But we do need more results to confirm this hypotheses





>>Is this possible? What is the feeling amongst the rest of the group? Are we restricting the performance of the solo F16 unneccessarily?





I fact we are not restricting the 1-up performance , we are in fact allowing it to have a little bit more theoretical performance to compensate for less effecient sailing cos you have to do everything yourself.



And also remember that 17,5 sq mtr. spi as a single hander is not small. It is in fact the biggest singlehander spi that is used. Others use 17 (FX-one/I17) , 15 (cirrus energy, old bim 16) or even 12 (Shadow/ old Bim 16)





>>The F18 class is gaining momentum in Australia. I'm not interested in sailing them because I love my lightweight cat rigged Taipan 4.9. I would however like to be able to put a spi on my boat and race them on equal terms. I have only one A-class to race against.



Well, if you are really going that way than I advice the following.



Downwind you'll be fine with the 17,5 sq. mtr. spi and probably a tad faster.



in the F16 1-up mode, and if you are slower overall at all, you'll probably be loosing out on the upwind leg and on reaches.



So in order to correct for this I would advice that you get a F16 sail for your Taipan mast. This sail has just a little more sailarea but more importantly it has a more area in the top and a squaretop to allow better twist when depowering.



However, I think that the standard taipan uni with F16 spi will be incredibally close to the F18 already. It will not be off by more than 1 or 2 % so where talking about 30 to 60 seconds in a hour here.



Regards,



Wouter

Thanks for clearing that up for me Wouter.



Rob

Hi everyone I'm new to the forum and look forward to exchanging ideas. I presently own a 4.9 cat rig which has been in dry dock for a couple of seasons since winning the Australian Nationals in 2000. Since that time I've been looking into developing a kite kit for the 4.9 that can be handled and used in our conditions (20 knots / 2 metre seas)



We are very fortunate to have a very strong fleet of skiffs where I live (Adelaide, Australia)including the recent 14 foot world champions. This is a boat type that has been developing fast kite designs for over 20 years and which could provide very useful information as a basis for cat kites.



To get to the point it has been found that the fastest kites are not necessarily the biggest and that the ability to handle them effectively can be as important as sheer horsepower. Based on the numbers evaluated to date it is likely that we will use a 16 m2 kite size which will have relatively high aspect to improve efficiency and reduce sheeting loads. I for one would not be concerned about limiting the cat rig kite to 17.5 m2 as this seems larger than necessary anyway - particurlarly, as Wouter points out, other (heavier) classes which tend to cater for the milder weather sailing regions have limited themselves to 17 m2 or less.



Cheers



James

AUS 153 'Woof'

James,

A 4.9 cat rigged with a kite. Would have to be a real blast.

I'm building a new boat and hope to move in the same direction when the new boat hits the water.

Have you decided on parameters such as hoist height and pole length?

Also have you decided on how your going to deploy the kite.



Regards,

Phill

I think I have a picture of you single handing the Taipan 4.9 on my desktop; nice jump off that wave if that is indeed you.



Welcome to this forum; personally I looking forward to your input on kites and kite setups as are several others I'm sure.



I also have some ideas I like to share. One is for getting rid of the excess of halyard when the spi is set. My first approach was a little complex but now I'm convercing to something far simpler and practical.



With combining the efforts of all on this subject and the rise of the F18 class worldwide I hope to give Taipans and F16's of all brands renewed momemtum.



Your conditions sound pretty much like mine although we have more chop here than swell so the waves maybe smaller but also steeper and break sooner.



Regards,



Wouter

James,



Indeed, I sailed the FX-one solo with its 17 sq. mtr. kite and I wouldn't want to go (alot) bigger. My current P18 kite is also 17 sq.mtr and when fitted to the Taipan felt okay. It also looked nice and proportional to the boat. The 21 sq. mtr. kite looks to big in my opinion.



As a side note, all modern cats with spi have converted to high aspect spis and the aspect ratio of the 17,5 sq.mtr. spi on the given gateheight (F16 rules) has the same aspect ratio as our main competitor the F18 boats.



The main reason that the 17.5 is in the rules is because that size has big merits for double handed sailing ; on of them is ease of handling with mixed crews or youths. Another is ofocurse the equality to the F18's. Without this rule in both modes crews will fear a big kite attack even when the likelihood of the merit of such an approach is questionable. Going smaller is never perceived as an unfair advantage therefor this rule is a convidence builder which is very important to the class. A perceived inequality is just a bad a real inequality.



Anxious to hear more about your experiences.



Wouter

James,



Does your post mean that you are keeping your boat and not going to sell it? How is the repaint coming along? I ended up buying Ian Verrier's boat after our discussion a few months ago and have been extremely happy with it, its in excellent condition - everyone who sees it asks me if its a new boat!



It only has a specialist cat mast unfortunately so I'm going to have to save up a pile of dollars to buy a sloop mast so that I can stick a spinnaker on it. I'm keen to sail cat rigged with spinnaker also so am keen to see how you get on.



Rob Wilson (Far North Queensland)

Taipan AUS175 ex Ian Verrier.

Hi everyone and thanks for the welcome



I should warn you up front that my project has a long time frame for a number of reasons so I will be reading your ideas more than writing in the beginning. Before looking too seriously at the kite I'm getting my boat back together (yes Rob the paint job is still on the cards before the next season) and making a couple of refinements before moving on the kite. One reason for the decision to go slow is that I'm not really happy with any options I've seen yet with respect what launching system to use. At the moment I'm leaning heavily toward the Inter type snuffer as ease of handling is definitely my first priority. Also , being a heavier sailor, I enjoy a pretty strong upwind advantage over most in conditions over 10 - 12 knots which is where I suspect the windage disadvantage would hurt the most. This system is obviously simple and probably a good starting point.



Windage is definitely a concern although not the way you might think. One of my close friends holds the world sailing speed record and the work his syndicate has done suggests that it is the extra wires and loose (unclean) shape of the suffer bag that will have the most detrimental effect. On this basis I want to develop an aerodynamic combined snuffer /pole/chute with minimum wires. The Kayak type system shown on the Tornado post earlier in this forum is along the lines I'm thinking although still too many bracing wires. The trick is to build a monocoque structure that is light and stiff - still working on that one!!

As far as the length of pole, kite size etc my aim is to develop something that fits within both the F16 and Taipan rules. This may mean a slightly smaller kite or shorter pole but since the relative gain for a cat rig will be significant I don't think this will be a big issue.

Anyway - look forward to reading your thoughts and seeing what you are all doing. I will aim to post my ideas as they come to light.



Cheers





James

AUS 153 'Woof'

>>The Kayak type system shown on the Tornado post earlier in this forum is along the lines I'm thinking although still too many bracing wires. The trick is to build a monocoque structure that is light and stiff - still working on that one!!





This is partly the reason why I like the Skunk system.



-1- it's mouth is just in front og the bridle strop which on the taipan is quite near to the mainbeam. In effect only 1.4 mtr. of pole is bagged in stead of the whole 3,25 mtr. on the big EO-snuffer or kayak type snuffer. the remainder of the bag in either on the trampoline or under it.



-2- The skunk bag is mad of a reinforced kevlar sailcloth that retains its shape (doesn't flap). It is forced into a flat oval shape by the mouth piece and the way it is fitted to the beam. In effect is has a rather small 5 cm or so height with a large 25 cm or so base. So it has the volume needed at the cost of only a smaller projected area.



Now both these points -reduction in exposed length- with the flat shape (exposed side area) reduce the overall projected surface area by a huge margin AS WELL AS the lever arm that this area has. With the added effect of no flapping I estimate a reduction of force just by these three effect by no less than a factor of 3 or 4.



The Kayak snuffer has a more aerodynamic shape but does again run the full length and its increase in overall surface area (not projected area) goes a long way in correcting back over the gains made by this more aerodynamic shape. Beware for intuitive perceived gains that are not supported by experimantal data.



An example : imagine you have three shapes -1- a sfeer -2- a sfeer cut in halve with the curved side facing the current -3- a sfeer cut in halve with the flat side facing the current.



How would you order the shape on accending dragforces ?



Answer by experimentaion (from my time a university) :



most drag = shape -3-

2nd place = shape -1-

least drag = shape -2-



Yes, this is really true ! Shape -1- looks more aerodynamic but when compared to shape -2- isn't. There isn't much difference between the two but shape -2- curves back to rapidly to maintain attached flow for long and it's big overal surface area induces enough extra drag to come out at more in total.



The only certain winner is to have less overall (exposed) surface area and secondly to have the least (exposed) projected area.



Another example : Those small square city cars not only consume less fuel because there are light but also because their frontal area is so much smaller that tehy can get away with having an awfull aerodynamic body shape.



The Skunk has a really small exposed area (the rest is on or under the trampoline) and a very small projected are (coz it is flat)



Maybe these consideration help you further in your quest for the ultimate snuffer.



As you can see I'm in for a discussion about it.



On a side note :



F16 and Taipan rules are exchangable right now. A Full compliant Taipan is F16 compliant although you'll be without the spi which is forbidden by the T rules. Personally I hope that the possible new Taipan rules will rule a spi setup that is teh same as the F16 setup. It would seem the most logical approach.



Regards,



Wouter

Robbie Daniels was sailing the Marstrom 20 with a support system for the Kite/chute pole. It was made of carbon fiber and followed a similar angle as the bridle wires on a sloop rigged boat (the M20 is cat rigged and has much higher angled brideles). The pole had no support or wires from the top. The carbon pieces supported the weight of the pole (gravity/downward) and the pull upward of the chute.



He said they were experimenting with it, but that he liked it so far.



Mike T- 213

I've was looking at a 10mm carbon tube from each bow to the pole tip and that was it.

I was also working on a shooter type device to be mounted in front of the main beam. I was working on a design that I think could be made quite easily. Virtually a home made modified Marstron setup. I think the Marstron shooter is a briliant concept but I was told it gives the kites a very short life span. This concerns me because that makes the setup expensive replacing kites on a regular basis.

I still think this would be the most efficient setup.

James,

*Waves across from the western side of the paddock*..

Come across for some serious breezes..



In regard to your thoughts.. You are lucky in that you have Alexander Sails in your backyard so to speak.. If he can be talked into a development program you should get some interesting results.. His I14 kites are quick.. Only Fyfe kites from NZ seem to perform consistently better (imho)..

I will be interested in seeing how skiff technology in terms of sails translates into cat kites.. Im starting to suspect the cat kite will end up being closer to a "code 0" jib then the skiff genacker..



I agree with your assessment of kites.. But 17.5 sq meters isnt excessive.. Its about the same size as a 29er kite and Cherub.. Way less than the Javelin, way way less than the I14 kites.. Im just trying to get as much luff length as I can..