Joined: Sat Jan 14, 2012 8:24 pm Posts: 780 Location: Houston, TX
You know, recently I've begun to doubt if my jib, at least the way I have rigged it, increases my pointing ability. This may be because my jib has no mast in the luff. When pointing very high, my jibs luff will suddenly backwind folding back slowing the boat. I then have to turn away from the wind to regain to flip the luff back. I can prevent this is several ways but they all result in no gain in pointing. So I have furled the jib and compared with main alone. When I do this I can't see gain or loss of pointing ability. It would be interesting to slip a batten into the luff and see if that helps.
When using the main and then unfurling the jib, I can measure a speed difference (varies from .5- 1.5mph) and feel it. I use my jib more for speed in lighter winds and to help with downwind performance (oddly enough) than I do for pointing higher.
_________________ Greg
2016 AI - Spinn & Jib
“Out of sight of land the sailor feels safe. It is the beach that worries him.” – Charles G. Davis
Last edited by vetgam on Fri Jul 22, 2016 12:01 pm, edited 2 times in total.
Joined: Fri Oct 24, 2014 2:13 pm Posts: 161 Location: San Antonio, TX
I'm glad the foresail conversations have sparked up again! Now that our light summer winds have returned, I've been trying to get back to my jib project. My boat is ready for a foresail - my mast topper is ready and I have a halyard for hauling up a sail. I recently came across a website that has some small cheap, used jibs for sale. They have a few around 30 to 35 square feet, with a foot that measures between 5 and 6 feet. I'm thinking this could at least make a good, cheap test candidate for a light wind genoa. I eventually want to do a roller furler, but if I was just to haul up a sail with the halyard, would a wire luff be the best candidate? What do you guys think of this?
Joined: Sun Apr 20, 2008 6:18 am Posts: 3062 Location: Sarasota,Key West FL
You might find a large 30-35 s ft jib/genoa might be a little much for the boat unless you brace the bow (the area around the hatch is too weak and you have great risk of folding the bow). Also the flotation on the AMA's is only sufficient for just the mainsail (and maybe a teeny jib). The boat will easily capsize unless you widen the boat to around 12 ft wide by extending the AMA's, if you do that then you can add any sails you like (whatever floats your boat (lol)). The mast on the TI is really bendy making it very difficult to get a jib from a rigid mast design to work correctly. Whatever you decide on I advise running on a roto furler so you can dial it down when needed. Just a couple suggestions FE
Joined: Mon Oct 13, 2014 5:45 am Posts: 36 Location: Japan
I am using a furling 45 sq ft Hobie Cat 16 jib. On the TI it overlaps the mainsail by probably a spec more than a foot. I haven't taken measurements recently to know what percent it is. The foot of the jib is 1.75m (about 5'9''). The way I use it, I have no problems with the size whatsoever. That is because I can so easily furl it to exactly the size that fits the conditions. There have been a couple of times I temporarily reduced the length of the jib foot to about half way to the mast. When the wind calms down I release a cam cleat, pull the jib line and adjust it to fit the wind in no time.
Switching sides is also a piece of cake. I can just let the clew rib against the main (not a big deal), or furl the jib in a bit, switch sides and release to full genoa length.
Also when the ama starts to spend too much time in the water, I move over to the haka to balance the boat. The other day didn't think there was enough wind to justify using the haka, but I switched from pedaling to sitting on the edge and leaning across the aka when the wind picked up and had an immediate speed gain over when I was pedaling.
For downwind sailing, by running a line from the jib clew out to the front aka where it connects to the ama I can set the jib to one side and the main to the other for about 130 sqft of downwind sail. Not a spinnaker, but it adds horsepower.
Then the other day my honey and I took just the center kayak portion to the lake for a pedal along the beautiful shoreline. No jib, no sail, just a beautiful day pedaling. It wasn't sailing, it was slow, but it was great! Adjusting to the moment and the mood, jib, haka, tramp, spray deflectors and even mainsail and ama are all optional.
...mark...
_________________ ...mark...
Enjoying a 2012 TI w/ hakas, a stainless steel mast topper & furling jib
Joined: Fri Oct 24, 2014 2:13 pm Posts: 161 Location: San Antonio, TX
Thanks for the input, guys. I ended up ordering a cheap jib, it's about 32 square feet. It'll only be for light wind use, probably under 10 mph, and I'm always hiked out when going windward, so I'm thinking I should be good with ama floatation. As soon as the ama starts burying, I'll drop the jib. That's the plan at least, I'll haul it up when I get it and see what happens!
If it ends up working out, my plan has been to brace the bow and put the sail on a furler. Although, I've been wondering, if the bow can handle the big Hobie spinnaker, then why wouldn't it handle a jib? I'm sure it flexes like crazy under either sail, but does a jib put more force on it?
Hokmark, how are those side stays working out for you? I like the idea of them as a way to help brace the mast, but do they get in the way of the sail when going downwind?
Joined: Sat Nov 05, 2011 1:58 am Posts: 2893 Location: Forster, NSW, Australia
The simple answer as to why a jib requires a stiffer hull is due to the circumstances of use. A spinnaker is basically designed for the wind being across the beam or behind it. This means that wind pressure will tends to push the masthead forwards. In addition, a spinnaker works best when it can billow more into a pocket-like shape. This involves having only moderate tightness in the halyard (On my TI so far, I have found that letting out a foot of halyard works well).
On the other hand, going to windward, the mainsheet will already be tight, pulling the masthead BACK, so if you were to add a forestay, even bare with no sail, you will already be adding an upwards force on the bow. If you add a jib, ideally you want a firm luff if you want to point higher. You can achieve this in two ways: 1) tighten the halyard, or 2) have a concave curve cut into the luff.
The former obviously puts a lot of upwards pressure on the bow, and with that big hatch opening, there is the risk of folding the hull. With the latter, windward efficiency never approaches the tight halyard method.
_________________ Tony Stott 2012 Tandem Island "SIC EM" with Hobie spinnaker
Joined: Mon Oct 13, 2014 5:45 am Posts: 36 Location: Japan
chadbach wrote:
Hokmark, how are those side stays working out for you? I like the idea of them as a way to help brace the mast, but do they get in the way of the sail when going downwind?
I like the way the side support lines work. I let the mainsail touch the line when I go downwind. If I didn't want to, I could pull the mainsail back just a speck with probably minimal loss of efficiency. The side stays give me a sense of comfort knowing that I am limiting the amount of pressure I am putting on the mast. The heavy duty bungees I use add gentle spring to the movement of the mast so it doesn't snap with on or off pressure. Before I set sail, I set the ropes so they are just barely taut on both sides - with the mast straight. With the masthead leaning about 2+ ft. the slack in the line by the bungee is used up and the rope appears to holds the mast from going farther. With my setup this happens at about the same time the ama on the leeward side starts starts being more in the water than out. That is also the time I start wanting to get on the haka or if no haka, the tramp, or if neither, just sit on the edge of the boat and lean onto the aka.
Regarding bow buckle, I used to use a 2 to 1 ratio pulley system to tighten the halyard. It made adjustment a dream, but wanting to simplify setup and not wanting to over tighten the line made me change to a one pulley system. When I tighten it, the mast with a loose mainsail is pulled forward just a little. It would be fun to get a scale that allows me to see how much pressure is being put on the bow. I am guessing that currently with my desire to be cautious, I furl the jib in so there isn't excessive upward pressure on the bow. But, I am not sure. I wonder too if climate might not make a difference. The climate here in northern Japan is cool. We have not turned on the air conditioner once this year and the inside of the house has never gotten above 77F. The lake I use most has a yearly high surface temperature just under 70F (20.4C) degrees. In the stronger winds, with water splashing on the boat, the temperature of the plastic doesn't reach what it would in many parts of the US. So I am guessing & hoping my guess is right, that buckling is less of a risk for me. Out of curiosity though, I just ordered a scale that will help remove line tension guessing.
Tonystott: Thank you for the helpful information in your 'simple answer'. I wonder if a hatch lid modification that prevents the lid opening from trying to buckle closed would be in order.
Fun stuff...
_________________ ...mark...
Enjoying a 2012 TI w/ hakas, a stainless steel mast topper & furling jib
Joined: Sat Oct 04, 2014 1:30 pm Posts: 984 Location: Benicia, CA
vetgam wrote:
You know, recently I've begun to doubt if my jib, at least the way I have rigged it, increases my pointing ability. This may be because my jib has no mast in the luff. When pointing very high, my jibs luff will suddenly backwind folding back slowing the boat. I then have to turn away from the wind to regain to flip the luff back. I can prevent this is several ways but they all result in no gain in pointing. So I have furled the jib and compared with main alone. When I do this I can't see gain or loss of pointing ability. It would be interesting to slip a batten into the luff and see if that helps.
When using the main and then unfurling the jib, I can measure a speed difference (varies from .5- 1.5mph) and feel it. I use my jib more for speed in lighter winds and to help with downwind performance (oddly enough) than I do for pointing higher.
A lot depends on the amount of camber built into the jib and the design entry angle the sailmaker used. If you told your sailmakers you wanted more speed in lighter winds, then he probably gave more camber and fatter entry than what is good for pointing.
_________________ R/Thom SeaRail 19 Triak BMW C600 Formerly Getaway with Custom Spinnakers Formerly raced F24 Mk II
Joined: Sun Apr 20, 2008 6:18 am Posts: 3062 Location: Sarasota,Key West FL
Vetgam: You already know how floppy the TI mast is, before going to a masted jib I tried many different jibs (I've had way too many). A common theme with them was they would potatoe chip on me, I don't know the correct sailing term for it (sorry), the problem I ran across was as soon as the jib had a load on it, it would bend the mast forward turning into a curved potatoe chip shape, I suspect because all the jibs were designed for other types of boats with way more rigid masts. I'm pretty sure I lost quite a bit of power, and pointing ability. I had side stays on similar Hokmarks, but there is a huge difference, he has bungys on his (briilliant, wish I had thought of it long ago). Instead I went to a rigid mast on the jib and no longer needed the stays, I kept them on there for a while but mostly used them for trapese lines (really silly), then I got rid of them alltogether when I got into the wing crap I'm currently using (I still have the rear stay on the boat, but that's mostly just used for anti-rotation of my mast topper, and on the few occasions I use my spinnaker (not very often anymore). My recommendation is before going to a rigid mast jib (there are downsides to it), you might try Hokmarks stay setup with bungys (the bungy's are the missing key on the TI mast problem I suspect). BTW, the reason my rigid side stays didn't work out so well is because with them on, I lost significant power in the main (it was designed around the flexy mast it appears). Just thinkin out loud here FE
From my gleanings on this site, it would appear that to properly form the luff of a jib the halyard pressure might cause the TI bow to be bend up, causing main hatch deformation, and thus allow shipping water etc... Some have added bow reinforcement to stiffen the bow and prevent this.
My guess this is the unstated reason Hobie has not come out with a jib is due to these design constraints.
I have been toying with the idea of adding another sail, and have been thinking about the spinnaker kit. I think I would prefer a jib as an all around solution as apposed to adding merely downwind as the spinnaker is designed for.
I'm intrigued by https://www.youtube.com/watch?v=NHdlrT3VPp4 that shows how to use trimaco drop cloths and contact cement to fabricate nice looking sails, and intend to go in that direction. I found sailcut cad tool that I'm attempting to use. to this end. I think I'll try fabbing up a jib on the cheap and see how it performs sans bow reinforcement.
I wanted to start with a traditional jib design rather than FE's wingsail, else I'd ask him for a sail plan.
Does anybody have a TI Jib Sail Plan they could share?
Joined: Fri Oct 24, 2014 2:13 pm Posts: 161 Location: San Antonio, TX
I've decided to initially install my jib with a furling setup. I'm going with a rigid mast (3/4" pvc) and built my furling drum last night. If I'm liking the foresail setup after a few trial runs, I'll build my bow brace. I'm currently trying to decide on how high I should have the foot of the sail above the bow. What determines this, is there a good starting point?
Joined: Sat Jan 14, 2012 8:24 pm Posts: 780 Location: Houston, TX
Chad ideally the foot of the jib sits lower than the foot of the main and should be at the level of the bow for maximum power. But I found that on the AI, that the jib was often overpowered with the foot so low . The bow gets pushed down and there was too much heeling for my taste. You could find yourself scooping water into the jib! Also that extra heeling slows the boat. I found the sweet spot to be about 6-8 inches off the bow. Some of is determined by how balanced your boat ends up. Weather or lee helm may require adjutments. The TI will be different than the AI. Where you sit may influence the boat balance and how high you set the jib. I would start at 6-8 in off the bow or just lower than the foot of the main.
_________________ Greg
2016 AI - Spinn & Jib
“Out of sight of land the sailor feels safe. It is the beach that worries him.” – Charles G. Davis
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