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PostPosted: Sat Dec 13, 2014 6:10 am 
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I would like to experiment with some different types of head sails on the AI as others have done. I would like to start with a jib. My biggest concern it that I will disrupt the balance of the boat and end up with an annoying lee helm. I intend to keep the jib small - about 21 sq ft. This would be a fractional rig, with the jib only extending up about 2/3 of the mast. It would be a working jib and go further aft than the mast. For those who have tried this, am I likely to get a lee helm that makes sailing difficult?

It would be modeled after this one.


Would I be better off with a jib even smaller? Would a smaller jib even be functional?


Vetgam


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PostPosted: Sat Dec 13, 2014 8:23 am 
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I have to ask.. what is it you are aiming to achieve? How can you attach a fractional kib to the mast without compromising the furling function?

I have heard of people adding a Hobie kayak sail on its own mast; would that meet your requirements?

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2012 Tandem Island "SIC EM"
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PostPosted: Sat Dec 13, 2014 9:02 am 
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vetgam:
If it were me I wouldn't use that design, there is no means to roto-furl the jib and main sail individually, and this can get you in trouble. There are times on an AI/TI in higher winds where you need to have the main furled in 2 or more turns, or the jib completely furled, and just run off the main, or furl the main completely, and only sail with the jib (extreme wind, using the jib as a storm sail (that's what I do)).
It's also nice to be able to use a halyard line to raise and lower the jib, so you can easily raise and lower the jib separately from the main, as there are times you just done need the jib. Having a halyard, you can also put the jib away, and launch a huge spinnaker if you plan on big downwind runs (spinnaker would be kept in a sail bag when not being used).
Also when the winds are over say 12 mph, you need to be able to furl in both sails a little to balance the load and lessen the weather helm.

If you go to the thread The ultimate Tandem Island ( viewtopic.php?f=69&t=33720 ) you can read through and find a really simple furl-able mast topper for your mast, that will help you.
Many guys have added jibs, if you find so posts from Captnchaos he had an AI and did a lot of experimenting with different jibs and concepts and designs, and shares a lot of his hard knocks experience on his posts. Many AI owner have just adapted the standard Hobie Kayak sail to there AI's (20 sq ft), with simple PVC roto-furlers. I think one of the tricks to success is be sure to have a rigid or semi rigid mast under the jib so you have something to furl around, and also because the AI mast is so flexible as it bends under load, the jib can no longer keep it's shape and folds into a U shape (too sloppy to work effectively).

One other minor point is both the AI and the TI have a minor annoying design flaw in the mast holder, that's that 1/4 stud at the bottom of the mast holder, side to side the mast is re-enforced quite well and you shouldn't have any difficulties, but forward to back strain can become a problem once you add the jib. As an example if you were on a strong down wind, and have the mainsail turned to one side and the jib to the other side (batwing configuration), the strain on that little stud is too much and it will break (I have broken quite a few without any re-enforcement), actually you can snap that stud easily just with the boat sitting in your yard, open the main sail all the way, and pull it tight, now give the control line a swift jerk (doesn't have to be too much), the stud will snap every time. The only solutions I know of are to add a rear stay line, which can take some of that load, or re-enforce inside the hull ( I added a small aluminum plate inside my hull) to prevent that stud from breaking. I have never had my boat out without a rear stay line on the mast, the rear stay line is loose 90% of the time, and only comes to play on a downwind. Actually if the 4 1/2 yrs I have had TI's, I have never gone out without my jib, except the first couple month I owned my first TI back in spring 2010, and quickly realized it desperately needed a jib, so I designed and made my own while waiting for Hobie to come out with the promised jib specifically designed for that TI, that never came out (I'm still mad at Hobie over that one, as I wouldn't have bought the boat had I known it didn't have a jib option).

I don't recommend you add side stays, as they really mess up the ability for the main mast to flex and spill wind, rendering the boat pretty useless. I don't recommend you model your jib after what you would normally see on a Hobie cat, those are designed specifically for rigid/stayed masts and don't work out so well on the AI/TI's, you basically have to work around what is already there design wise ( ie... rear stay line, rigid mast for jib, roto-furling separately from the main, and the ability to drop it easily while out on the water, etc, etc , etc).

You can't change the flotation on the AMA's, basically it takes a certain amount of side force (heeling moment) to tip the boat, adding a jib makes it worse (more sail area). Of course you can always hike out on the tramps when running a reach but most people would rather just stay in their seat, so this severely limits what you can do with jibs and spinnakers.
As an example on my TI flying all 265 sq ft of sail and both me and my wife hiked out, we have sailed over 20 mph a few times (obviously the winds were over 20 mph at the time), however in my opinion it's not worth it, it's way to rough, wet, and dangerous, if you want to do that, just get an H16, or a WETA. You will find the jib on a broad reach adds maybe one-two mph to your speed at best. But does allow you to point upwind much higher with more speed (1-2 mph faster with a better VMG), and it also greatly improves the downwind performance, which is not so hot on AI/TI's anyway.
Good Luck, hope this helps you
Bob


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PostPosted: Sat Dec 13, 2014 11:10 am 
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My goal is to use a jib in light winds that can be removed (before or during the sail) when the winds pick up. This system actually has a halyard even though it rolls up in the mast. I would have the mast sleeve reinforced with some loops of fabric so that the jib halyard is attached 1/3 of the way down from the mast. That we have worked out. Supposedly when you furl both sails together the remaining exposed portion of the sails acts like a lateen rig (not that I know what that fells like). I have not made the final decision on the furling mechanism yet and appreciate everyone's thoughts.


This AI has TI amas so I think it should handle the heeling. My real concern is upseting the balance of the boat. Did it not cause lee helm in your TI Bob when you were using a standard jib?

Is a smaller jib- say 10-15 sq ft too small to be functional? I hate to use a backstay if I can avoid it. Others seem to have avoided them but then again they probably don't tell us when the mast base breaks.

Vetgam


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PostPosted: Sat Dec 13, 2014 12:23 pm 
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I have a Triak that is designed similarly to the AI or TI...that is it has a roller reefing mainsail. I put a small headsail jib with a little mast overlap tacked about 1/3 back from the bow (attached with a line going between two cleats). I made the jib fractional by only making the luff 2/3 of the distance to the mast top. The whole jib is about 1 sq m in area. There is a bit of free halyard at the top but I have found that it doesn't make a lot of difference. I put the jib on for the same reason you want, higher pointing, easier tacking and more power in lighter winds. Here's the true difference between what has been done on the AI's and TI's and what I did. I made the jib from lightweight material (soft poly packcloth or nylon ripstop) and snuff the jib when I don't want to use it anymore. I made the snuffer from a rubbermaid trash can with the bottom cut out. You can see it here...the triak also carries a snuffable spinnaker. [youtube2]https://www.youtube.com/watch?v=3XumzDHLJbw&list=UUKUwoGV9eRVRwT5C0YL6uRg[/youtube2] Anyway, by moving the tack back from the bow, you eliminate a LOT of the lee helm but still get the advantages you want. I've sailed with the jib in up to 10 kts of wind which is typically when I also have to start reefing the mainsail (Triak does not have as good stability as the AI or TI-but it is a dryer ride because it is a "sit inside" kayak and the single aka is behind the driver). The lighter weight material starts to deform to a poor sailshape in the heavier winds but since I didn't need it then, it was OK (sailboats and compromise are synonyms, right?). :wink:

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PostPosted: Sat Dec 13, 2014 1:38 pm 
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Tony , the halyard is attached to the mast by a hole in the mainsail and a loop around the mast. I don't want to do that to the mainsail so I will sew into the mast sleeve a long strip of strong material with a couple of loops every foot or so for flexability when using different head sails in the future. The halyard block is very small and rolls up in
mainsail without a problem.

http://youtu.be/9qMMHNXqLt8


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PostPosted: Sat Dec 13, 2014 3:02 pm 
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Vetgam:
If your not planning a huge spinnaker as well you should be ok without the rear stay. My mast stud only broke doing extreme sailing and usually involved the spinnaker.
I wouldn't worry about lee helm so much, as the AI has way more rudder than the TI.
As long as you have a halyard and have some means to get rid if the jib if the winds do pick up too much you should be fine. The jib only really helps in light winds, once the wind gets above 10mph, the mainsail alone has plenty of power, I think that's why most don't use jibs, they simply say home in light air.
On my TI with the original 40 sq ft jib weather helm would creep up in winds over about 8 mph, I kept re-cutting the sail smaller and ended up between 25 and 30 sq ft which seemed to be the sweet spot on the TI. I'm guessing the sweet spot on the AI will be between 20 and 25 sq ft.
Most of my extras (ie... Bowsprit, re-enforced hull, furling spinnaker and jib, motors, etc) were more for extreme offshore sailing, in light air you don't need most of that extra crap.
Anymore with my jib I find the downwind to be acceptable enough so I very seldom even use my spinnaker anymore, I leave it at home when in sarasota, and only take it along sometimes when we plan to do long hauls down in key west, actually I'm thinking about retiring the spinnaker for good.
Bottom line I think your setup will work fine for what you plan to do.
Bob


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PostPosted: Sat Dec 13, 2014 4:45 pm 
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Thanks for all the advice guys. Before I go out and have a sail maker make a jib, any of you found a clever way to test drive different sizes and shapes before committing to one? Can you cut bed sheets and latch the corners to do this? Will sail makers rent out different jibs for dinghys?

I obviously have problems with commitments.

Vetgam


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PostPosted: Sat Dec 13, 2014 5:27 pm 
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I think what most do is adapt a jib from a similar sized boat, try contacting the guy in the video and ask him what jib he used. Most sails and jibs for most boats can be purchased aftermarket. If you go to the sail rite web site, they have a pretty big selection to choose from. I design and make all my own sails, so my only cost is the materials. In my case I read everything I could about designing and making sails for a couple years before laying down the first one, it's all part of the hobbie and a learning experience for me (something to keep my hands and mind busy). The best part for me is the testing, that's one of the things that drives me to go out pretty much every weekend, trying out my different designs and tweaks. Some of the stuff works out great, others not so much (lol).
It's not the final destination that counts, it's the road getting there and the learning along the way that is the most fun for me.
Hope this helps
Bob


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PostPosted: Sat Dec 13, 2014 5:41 pm 
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My main concern is that as soon as you begin to furl the sail(s), the jib will immediately take on a shape which is totally unsuitable for the task, as the clew will be wrapped around the mast, while the luff will take on a greatly curved shape. This in turn will negatively affect the performance of the main sail.

It seems to me that with this arrangement. you would need to completely douse the jib before attempting to furl the mainsail, making the use of the jib effectively an on-off switch.

Thr only way to avoid this IMO is to follow Bob's example, and have a jib halyard leading from a crane device on the masthead (probably matched by a crane at the rear to run a backstay to the stern, to help keep the crane aligned fore and aft), which in turn will need to be able to remain in place while the mast rotates beneath it. You could then lower the jib (as well as furl it and/or adjust the sheeting angle) independently of the mainsail furling.

Using Bob's comments regarding the relativerly modest perfomance gains involved, together with the need to strengthen the location of the mast base, I tend to question whether the benefits justify the complexity, but that is just me.

Good luck though :)

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2012 Tandem Island "SIC EM"
www.scenefromabove.com.au


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PostPosted: Sat Dec 13, 2014 7:02 pm 
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My reasons for adding the stuff I did was to try to get a little more sailing performance in the typical local winds in this area (3-6 mph) through ten months of the year ( I go out every single weekend). When I bought my first TI the condition was to promise to use it as my exercise program and pedal the boat around 15 miles every week. We also use the boat as our family boat when we have friends and relatives visiting. The things we like to do most are snorkeling, scuba diving, and island hopping in the keys. Basically replacing our old 24 ft sea ray. We are also pretty avid kayakers, and love the TI as a tandem kayak. The TI fits the bill for us perfectly and does everything we want it to do. I know of no other craft that can do all the things an adventure boat can do, it's truly the SUV of the industry. One of the key features is the boat can be easily modified to suit what people use their boat for mostly. I don't fish (except spear fishing) but if I did, an AI/TI is what I would be fishing off of (especially offshore).
I think Matt Miller said it best, there is no day you can't take an island out and have fun.
Bob


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PostPosted: Sat Dec 13, 2014 7:57 pm 
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Tony I think I'm just looking for something new to do. My wife and I just finished our first sailing courses. After sailing a few different boats it's made me appreciate the Islands even more so I wanted to try some of these learned concepts on the AI. It's interesting that the owner of the boat in the video has more recent videos and the jib is now missing. Maybe making a jib is a sign of some sort of sailors midlife crisis that I will get over once I have one. Just got to keep experimenting :D

Thanks for the help.
Greg


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PostPosted: Sun Dec 14, 2014 12:05 pm 
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vetgam wrote:
Thanks for all the advice guys. Before I go out and have a sail maker make a jib, any of you found a clever way to test drive different sizes and shapes before committing to one? Can you cut bed sheets and latch the corners to do this? Will sail makers rent out different jibs for dinghys?

I obviously have problems with commitments.

Vetgam


If you have some tarp material and a sewing machine you can easily loft your own trial jibs. Cut the tarp into the rough size of triangle you want to try. 1/3 down from the head cut a slit horizontally in the fabric from the luff (actually is best to cut perpendicular to the leach instead of horizontal-but either will work OK). The slit should end 40% of the horizontal distance between luff and leach starting at the luff. Sew the material back together but make the fabric overlap wider and wider (this is called a broad seam)-it should be in the shape of a golf tee. The end amount of cloth you "gather" at the luff should be about 10% of the length of the slit. Do the same thing at the 2/3 spot (note, this will be a longer slit). These slits are adding camber to the sail and the max camber will be around where you start the slit. You should also sew a small dart at the midpoint of both the leach and foot (this will keep the leach and foot from flapping). You should reinforce the corners with patches of additional tarp material. Put grommets (or sew a strap) onto each corner and go out and try it. Good luck.

As an aside, if you want to reduce the lee helm, move the tack point aft toward the mast and increase the amount of overlap past the mast. Remember, though, that you don't have too many choices for sheeting points.

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PostPosted: Sun Dec 14, 2014 1:00 pm 
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Concur- a polytarp and some seaming tape can make an effective test rig on the cheap.

Seamstick works well for a temp no-sew sail:
http://www.duckworksbbs.com/sailmaking/tape/index.htm

They also stock a grommet kit although those are available at most hardware stores.

I've also made kayak covers this way, using gorilla tape to join the panels and seams. Works fine to keep dust and dirt off when storing in the shade.

-RH

Addendum: Polytarp sews fairly well also - so if you've got a machine and the skills, you can make one that will actually last. There are plenty of books on making sails this way.

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PostPosted: Sun Dec 14, 2014 2:14 pm 
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I agree, if you don't have a sewing machine, permanent fabric glues will work pretty well on tarp fabric. Some seamsticks will work as well. I have a sewing machine, so I prefer to sew since I know that it will hold that way. If you do decide to use glue or seamstick, suggest stapling the broadseam at the luff-I'm a belt and suspenders kinda guy.

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