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How-to AI Jib Video
http://www.hobie.com/au/en/forums/viewtopic.php?f=69&t=56478		 Page 1 of 2
Author:  vetgam [ Sat Nov 21, 2015 10:01 pm ]
Post subject:  How-to AI Jib Video
It took me a while but I finally got around to putting this video together. It details the self taking jib from top to bottom. At the end, I show how I attach to jib to the top of the mast. It also includes other modifications I settled into over a three year period. It includes on-the-water demonstrations as well as on-land details.

Hopefully this can serve as a road map for others looking for a convenient way to add more sail to their AI or even TI. I remember being intimidated when first considering a jib. Thanks to on-line sites that provided pictures I was able to figure it out. There is really nothing difficult about it and no permanent modifications are necessary. After a year of re-rigging and fine tuning I am now convinced this arraignment is about as simple and functional as a jib can be. Thanks to all who shared before me. Special thanks to Roger Mann and his designs.



https://www.youtube.com/watch?v=DEofPRTQM24
Author:  TI_Tom [ Sat Nov 21, 2015 10:50 pm ]
Post subject:  Re: How-to AI Jib Video
OK, you piqued my interest. Now, about that video.;)

Sent from my SPH-L720T using Tapatalk
Author:  Blasius [ Sun Nov 22, 2015 1:21 am ]
Post subject:  Re: How-to AI Jib Video
Thank you, for the video.
Very clear explanation, now I have many things to study .........
Author:  BobAgain [ Sun Nov 22, 2015 7:17 am ]
Post subject:  Re: How-to AI Jib Video
Thanks for posting that, Greg. Nicely done.
Author:  Haliboo [ Sun Nov 22, 2015 8:52 am ]
Post subject:  Re: How-to AI Jib Video
Thanks for taking the time to post, some really interesting additions... :D
Author:  TI_Tom [ Sun Nov 22, 2015 9:20 am ]
Post subject:  Re: How-to AI Jib Video
Now I see it.

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Author:  TI_Tom [ Mon Nov 23, 2015 10:34 am ]
Post subject:  Re: How-to AI Jib Video
Vetgam,

Could you post line/halyard lengths for the AI guys? I know they will be different for the TI folks, but it gives me a starting point. Thanks!
Author:  vetgam [ Mon Nov 23, 2015 12:58 pm ]
Post subject:  Re: How-to AI Jib Video
Not sure of the exact length. Here are the jib dimentions.
Luff 133 in.
Leech 117 in.
Foot 51 in.

So the halyard must be about 124 long I would guess. That is only the portion connected to the mast. The other half lives in the cockpit pocket.
Author:  tonystott [ Sun Nov 29, 2015 1:27 pm ]
Post subject:  Re: How-to AI Jib Video
Thanks Greg, for the very informative video plus your copious comments on the jib project. It prompts some questions of my own.

I would have thought that the primary purpose of the jib is to aid pointing when sailing to windward. However, I see in the video that the luff of the jib is always very loose. Have you tried increasing the tension on the luff?

(I also note that the jib seems to be radially cut, which is unusual for a jib). What are the advantages of that construction?

I am starting to look round for a second hand jib from one of the off-the-beach sailboats, as your system only needs 3 blocks, 2 cleats and 2 snapshackles/carabiners, plus 3mm line, so a cheap sail makes the whole thing quite economical. I am very tempted to follow your design, but am in two minds about instead waiting for Hobie to eventually release their reacher kit.
Author:  tsquared [ Sun Nov 29, 2015 1:42 pm ]
Post subject:  Re: How-to AI Jib Video
What are the advantages of this jib? Faster speed or better sailing point or...? Curious.
T2
Author:  vetgam [ Mon Nov 30, 2015 11:32 am ]
Post subject:  Re: How-to AI Jib Video
Quote:
I would have thought that the primary purpose of the jib is to aid pointing when sailing to windward. However, I see in the video that the luff of the jib is always very loose. Have you tried increasing the tension on the luff?


Tony, I originally tensioned the jib like any other jib and made sure the self tacking feature maintained the normal shape. Later I decided to add the tensioner to the self tacking jib just to find the best tension and to see if the ideal tension varies significantly with points of sail and wind strength. I found that it did vary enough to leave the tensioner in the rigging. Oddly I found that I had a speed boost if I relaxed the jib more except when in a close reach, thus the looser jib. When I am trying to point high the jib is tensioned normally. I wondered if anyone would spot the looser jib in recent videos.

Quote:
(I also note that the jib seems to be radially cut, which is unusual for a jib). What are the advantages of that construction?


My understanding is that the radial cut allows the sail maker to minimize stresses on the high stress areas of these light weight sails. The advantage is longer life. Code 0 material is very light. I've been told radial cuts maintain the designed shape/camber when the lines are tensioned or winds change. I will call the sail maker today and get his take on why he chose this cut. The cheaper crosscut jib allows the user to alter the shape and camber better using jib lines and works well with heavier materials. At least this is my understanding. A crosscut jib might work just fine. I wanted a very thin material that I could roll up easy when taking the jib down to store it. This led to my choice of material and ultimately the cut of sail.

Quote:
What are the advantages of this jib? Faster speed or better sailing point or...? Curious.


When I tested the speed difference I did not have the ability to quickly drop and raise the jib. I was using jib sheets not the self taking mechanism. I measured (GPS) about .5-1.5 mph increases when the jib was up. I will need to redo the testing with these changes and report back. To me the bottom line is the advantages are mild increases in speed, better pointing and getting more out of lighter winds. Now I can sail in wind ranging 8-10mph where before I needed 10mph or above to enjoy sailing.

It will be interesting to see if the reacher and the jib compliment each other or if the reacher can help with pointing too. Will let you know in February!
Author:  chadbach [ Mon Nov 30, 2015 11:51 am ]
Post subject:  Re: How-to AI Jib Video
Vetgam, I'm starting to think about putting a jib on my TI but am debating between this set up and a setup with an independent furling jib and rotating mast topper. On your setup, when the winds pick up and it's time to reef, do you still get the pointing benefits of the jib when it's partially furled into the main? Or is it best to drop the jib and continue on with only the main sail?
Thanks,
Author:  vetgam [ Mon Nov 30, 2015 12:12 pm ]
Post subject:  Re: How-to AI Jib Video
Quote:
. On your setup, when the winds pick up and it's time to reef, do you still get the pointing benefits of the jib when it's partially furled into the main? Or is it best to drop the jib and continue on with only the main sail?


I could not honestly answer that because I can't drop a half furled jib to compare. My gut feeling is that I would not be pointing as efficently. But this is probably true of a partially roller furled jib too.

My boat is an AI. With a jib out I have found that I beat a TI to a target directly upwind. That same TI spanked me going downwind though. Going to need that reacher!
Author:  chadbach [ Mon Nov 30, 2015 2:05 pm ]
Post subject:  Re: How-to AI Jib Video
Makes sense. I do like the simplicity of your system - being able to furl/reef both sails at the same time.

That reacher does look like it'll be a fun sail!
Author:  vetgam [ Mon Nov 30, 2015 4:24 pm ]
Post subject:  Re: How-to AI Jib Video
Remember that the roller furling jib does not work for someone who fishes for larger fish like we do offshore. The furled jib stay will interfere with you bringing your rod around the front of the boat. On the other hand, a jib that furls into the main does not need a forestay so there is no interference.
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