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PostPosted: Wed Oct 24, 2007 8:18 pm 
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I am working on a spinnaker for the AI. I have a blog site with some photos and Info. Read the blog "Spinnaker Ideas for the AI" and see the photos in the photos section under Spinnaker. Here is the link.

http://brakeman.multiply.com/

Let me know what you all think.


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PostPosted: Wed Oct 24, 2007 8:38 pm 
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Well, I looked at your pictures and it seems that you are looking at a symetrical spinnaker. Which would work, but it will only help straight downwind and probably won't add that much thrill unless you are using it in some big wind.

If you look at the spins that catamarans run they are asymetrical and cut very flat compared to the spins you had pictured. Also one side of the spin, known as the tack, would be attached near the bow or possibly even to a pole sticking out in front of the boat. The the head of the sail would be attached near the top of the mast and then the clew would be the where the control lines attach and they would be on the same corner, almost like a giant jib, just cut fuller.

A spin rigged like I described would be better for the AI, seeing that it reachs higher speeds, and a spin like I talked about could be used on any point of sail except upwind and might really boost the speed of a reach and in theory should lift the bow and keep the amas from diving as bad on a hard reach.

Like I said go look at a few pictures of the Hobie tiger's spin and you will see what I mean. They work great downwind and can be used alot higher than the spins you had pictured.

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Nacra 5.2 "Elsies"
Hobie 14T, "Blazin" I guess I am keeping her!


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PostPosted: Thu Oct 25, 2007 6:57 pm 
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So if I use a asymetrical sail it will be attached like a jib. I can not attach a pole to the AI but I can attach the tack to the front of the kayak and the other (clew) attached to two line running through the amas. I would just have to get the sail shpe right. I am worried that if the sail is too big it will put a lot of stress on the mast and cause damage. What do you think about that. Thanks for the help.


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PostPosted: Thu Oct 25, 2007 10:33 pm 
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First off, I am not a spinnaker expert, but i have been doing alot of research recently about them because I just rigged one on my cat.

Yes, the front of the sail would attach near the bow, and the other side would be sheeted to some point back near the rear of the boat. Where would depend alot on the size of the sail. This video is a good example of what kind of spin I am talking about.
http://www.youtube.com/watch?v=Lvdnrt39b8U

I can't be sure, but I have always heard that asymetrical spins placed lower loads on the mast, but I don't have any way to confirm that. If you keep the main sheeted in pretty tight it would add support to your mast. Plus once again comparing this to a cat rig, it would be best to not attach it to the very top of the mast. Maybe just over 3/4 of the way up that mast. That limits you to a smaller sail but also keeps the loads alot lower on the mast where it is stronger.

Here is a very crude drawing of what I picture
Image

red=mainsail
yellow= spinnaker
Black dots on rear beam= block for spinnaker
Blue= spinnaker sheet

You would keep the mainsail in pretty tight like we do on our cats to provide support for your mast, and you would not go straight downwind, you would tack or gybe downwind just like we do on our cats.
As you can see the spin would come back past the mast but as you gybed you would let it blow out front and then pull it to the other side.
The sheet as you can see will be attached at the clew of the sail then would be let backwards to the block then through the other block then back around to the clew again. Thus giving you a continous sheet which= less mess and much easier to use.

This could all be rigged very easily to be snuffed through the front hatch on the AI, if you look at how cat spins are snuffed you will see that it would be easy to rig a system that would function as a halyard and a snuffer line.

Well, that might be an overload of info. Just post any questions you have and I will try and answer them to the best of my ability. I would like to see this work.[/img]

_________________
Nacra 5.2 "Elsies"
Hobie 14T, "Blazin" I guess I am keeping her!


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PostPosted: Thu Oct 25, 2007 10:56 pm 
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So it is really late and I am kinda bored so here is kinda what I would picture the rig would look like from the side. Things may be way out of proportion but you get the idea.
Remember the spin could be attached lower on the mast, Also the blocks for the spin might not be on the rear beam, they might be out on the amas's.
Image

Hope this helps.

_________________
Nacra 5.2 "Elsies"
Hobie 14T, "Blazin" I guess I am keeping her!


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PostPosted: Fri Oct 26, 2007 10:12 am 
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Hey Gree2056,

Thanks for the responce. I think I understand what you are talking about. The first proble I see is attaching to the mast. I am not sure if you are aware of the mast. It is not fixed like the Cat. It is inserted in to a holder that has bearings and fully rotates around. That way the sail rolls up around the mast. So if the spinnaker is to attach low on the mast it will be difficult. I was thinking of attaching it to the top of the mast using some kind of rotating block. I will try to draw up a picture today. Thanks


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PostPosted: Fri Oct 26, 2007 2:28 pm 
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Well, first of all I did all that posting after getting back from a party and really don't remember writing most of it, but it all makes some kind of sense and the drawings are relevant so we are good.

I had forgotten about the 360 degree rotating mast. Is the sail sleeved over it?

I can still think of a few ways to attach the spin lower, it would just have to be able to be wrapped up with the sail and you would have to have a small hole cut in the front of the sail wrapped around the mast to allow for a small block to be attached. But that would all be more difficult that the top idea.

Something you might look into is a sail called a hooter, once again it is basically a huge jib and would be very close to the sail I have described, but instead of snuffing down into a bag or port it would furl like the jib on the Hobie 18 or the 14T. This would be a simpler system and according to Rick White (the guy who runs catsailor.com and has written many books on catsailing) they are just as fast downwind as a spinnaker and they have the added advantage of being able to be used upwind in light wind and would provide some extra umph! upwind when it was barely blowing. One of the Hobie jibs might even work for this because they would reach the top of the mast.

Just some more thoughts, keep the questions coming!

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Nacra 5.2 "Elsies"
Hobie 14T, "Blazin" I guess I am keeping her!


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