Jibs and the TI

Here's an older article that does a very good explanation of lee helm, weather helm and neutral helm. Our boats don't have the luxury of being able to adjust things like mast rake, rudder rake, etc. but the article is worth a read, anyway. http://www.catsail.com/archives/v2-i8/feature1.htm http://www.catsail.com/archives/v2-i8/feature1.htm

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R/Thom
SeaRail 19
Triak
BMW C600
Formerly Getaway with Custom Spinnakers
Formerly raced F24 Mk II

interesting. i have 2 questions:
- why did you use the backstay line to protect the mast from rear forces if the jib is used only or mainly for upwind sailing? what do u think about a solution with forestays and no backstay also avoiding the mast furling problem?

- why it is completely useless downwind? though it is covered by the mainsail i thought it could give u some little more power

another note. if, as everybody say 8and i agree the secondary sail (jib or spi) shoudnt be used with winds at more that 10/12 knots isnt'it better to use a cheaper material as lankotek? in a normal boat jibs must be very strong and hold 30-40 knots upwind but this is not our case...

The AI/TI mast is bendy. This is actually a good thing in a cat rigged boat since the mainsail automatically depowers in puffs (the mast bend takes camber out of the mainsail). BUT, for a jib to work to weather, there must be a taut luff--if the luff is not taut, the sail gets pushed inward which gives MORE camber and moves the center of effort aft so you can't point with it. SO, these enterprising people have given the mast a backstay so the jib luff stays firm. IF you repowered the boat with a stiff mast, then you wouldn't need the backstay and could just use a forestay and mainsheet tension to keep the jib luff taut.

The jib is probably not completely useless downwind, it is just that it won't provide a lot of difference on a broad reach since it is very small compared to the mainsail.

Lankotex is stretchy. Jibs must be made out of a fabric that is dimensionally stable to the extent possible-this is so that the center of effort of the jib is positioned 35% aft of the luff--if it moves aft of that spot, you can't point. Even in 10 kt breeze your boat may be going 8 kts so the jib is seeing 18 kts of wind. You can make a jib out of Lankotex but you would have to make it often since once it stretches, it stays stretched. I posted a video a while back making a jib out of a tarp for those folks who just wanted to try a cheap jib to see what it would do. Here's the link https://www.youtube.com/watch?v=buyi5mu ... 0r&index=2 Granted, you can make a bunch of jibs out of tarp before you will get to $400-but most folks would rather sail than make sails.

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R/Thom
SeaRail 19
Triak
BMW C600
Formerly Getaway with Custom Spinnakers
Formerly raced F24 Mk II

What tpdavis473's said. The only other comment is this. There is a BIG advantage to the Hobie snuffing system. Their system allows you to adjust the forsail up and down off the bow WHILE being flown. What this does is allows you to change from a very tight luff as you sail upwind to releasing the luff to fly the jib as a mini spinnaker, positioning it as much as several feet off the bow when going downwind. Because the jib now flies more forward of the bow, it is less influenced by the main blocking wind. You feel the performance lift. Enough benefit that I often decide to avoid changing to the spinnaker out of lazyness.

I have stopped looking at any other way to rig these headsails. Once you buy the Hobie Spinnaker rigging, you are set to fly any headsail you want. A few quick releases and changing from one headsail to another while out on the water is a breeze. As versatile a system as anything we could hope to build- but it there for us to buy.

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Greg

2016 AI - Spinn & Jib

“Out of sight of land the sailor feels safe. It is the beach that worries him.”
– Charles G. Davis

I use the jib on all points of sail. It helps a little bit on a broad reach and gives a decent little boost if I fly it wing-on-wing with the main.

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-- Chad | 2014 TI

when i asked him what happened to the jib project, this is what matt responded:

It was determined that the stress on the hull was too much, so the project was shelved in lieu of the spinnakers. One of the engineers actually folded a bow.

Maybe that engineer didn't know how to trim a sail? We've seen quite a few examples of non-engineer types that have successfully added jibs to their AI/TI without folding a bow. Additionally, the Hobie jib project was conceived way back in 2010. Back then the plastics recipe may have been slightly different allowing for more flex. Even if they were worried about folding a bow, I'm sure Hobie's engineers could come up with an internal bracing solution. I'm a firm believer of never saying something can't be done.

Sent from my SPH-L720T using Tapatalk

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2015 Hobie Tandem Island Hibiscus
"Third Normal Form"

• Trampolines
• Hobie cover
• Davis Spar Fly
• Kayakbob's Sprayskirts
• Spine Board Hakas

It was probably while he was trying to trim the jib that he folded the bow. It is common to haul the halyard/forestay tight to make a jib work upwind. It's even worse to try to get the luff of a bowsprit mounted screacher to be tight enough for upwind work (I broke off the bow of my F24 Mk II as did other owners). The leverage is tremendous (of course there were winches and waves involved). There's also the compressive force on the mast trying to drive it through the bottom of the boat. Truthfully, a spinnaker is both more useful and easier on the boat for me. A jib helps about a knot to weather, the spin helps about 5 kts downwind. Of course, I carry both because I like to play with stuff.

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R/Thom
SeaRail 19
Triak
BMW C600
Formerly Getaway with Custom Spinnakers
Formerly raced F24 Mk II

My jib designed for a Hobie 16 cat. is 44.8 sq ft and has a foot of 1.75m (5ft9) or so. So, I am probably over 110%. It is too big, I think, but because it furls to what ever size I desire, I haven't found it to be a problem. In lighter winds, I appreciate the larger size. I have no back-stay and don't find that to be a problem.

Anyway, I have had no significant lee helm in any of various wind conditions. I have noticed that in stronger winds I tend to loose any advantage in pointing into the wind. I had some stronger winds I was fighting with the other day. The wind was also changing directions constantly. After about 5 minutes of trying to deal with it, I furled the jib and just use the main furled a couple rounds. That was work enough.

I sailed with an AI owner today who came to check out my jib. We had a variety of wind strengths through which he did the sailing the entire time. He was surprised that there was no lee helm and that the rudder control was so easy.

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...mark...

Enjoying a 2012 TI
w/ hakas, a stainless steel
mast topper & furling jib

Interesting Mark, we all seem to be finding that the main alone is best for pointing and that the jib is about adding speed (about 1-1.5mph on my boat). I did find a notable difference in my ability to tension the luff when using the jib in the Hobie spinn rigging. The tight luff is allowing me to point significantly higher but still about 5-10 degees short of what the main alone can do.

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Greg

2016 AI - Spinn & Jib

“Out of sight of land the sailor feels safe. It is the beach that worries him.”
– Charles G. Davis

I forgot to mention that my jib also does not help with pointing. It actually seems to make it worse, which I'm not surprised due to the lee helm.

So what the heck are you TI guys doing to not get lee helm? I can see the AI being more balanced with a jib since its mast is more towards the center of the boat, but the TI with a jib, on the other hand, has a whole lot of forward CE.

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-- Chad | 2014 TI

I dunno either. BUT, I could guess that their boats have more weather helm built in, so the transition is to neutral helm or slight lee helm that they don't notice. Could also be that they move their body weight forward to change the CLR forward to bring the CLR closer to the new CE of the sailplan.

If you aren't able to point better with the jib than without it, then the jib is probably seeing more luff sag than it was designed to have (ie, the jib forestay/luff isn't tensioned as well as the sailmaker expected). If you are going to have a new sail made, tell the sailmaker to increase the luff sag--even better, if you can get a picture from off the boat while going to weather with the jib--give that to the sailmaker...he might be able to get a better jib for you. He might not, also, though because sailmakers bye and large all use software for designing sails and some of them don't include the possibility for adjusting for more luff sag.

If you want to try to correct your current jib for excess luff sag, you can do it by stages. Don't try to increase the existing luff tension beyond what's reasonable for you to tug since you don't want to break your boat. Instead, start by folding the hem along the luff one turn and sew it down. Go sail and see if that helps you point. It may not...since your mast is bendy, the mast is falling off to leeward, so your forestay is offcenter. I've seen some photos/video of your boats with jibs-granted, the fisheye lens probably makes it look worse than it is, but some of them seem to be way out there to lee.

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R/Thom
SeaRail 19
Triak
BMW C600
Formerly Getaway with Custom Spinnakers
Formerly raced F24 Mk II

I wonder if 110% jib is too much and maybe 100 or 85% might be better for the TI. I imagine a 130 genoa is asking for major Lee helm too.

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Greg

2016 AI - Spinn & Jib

“Out of sight of land the sailor feels safe. It is the beach that worries him.”
– Charles G. Davis

You're right, the jib is way off center, pushed out to lee. With the way I have mine rigged, I have an idea of using side stays at the head of the jib to maybe help keep the it centered. I just need to get back out on the water to try it!

I like the idea of folding and sewing the hem. I may give that a try if I get brave enough with my wife's sewing machine!

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-- Chad | 2014 TI

Since the CE of, say, a 130 Genoa is more aft than that of a 100 or 85 jib, I wonder if there would be any noticeable difference in helm between the headsails.

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-- Chad | 2014 TI