Jib Physics & "the slot effect"

I share the concern, so added side stays. I have them set so that they do nothing until a certain point at which the bungee starts to stretch until it reaches the limiting point built into the stay. The bungee connects two loops of rope so that when the bungee is near maximum stretch, the line is tight, holding the mast from going any farther.
In the experimentation I have done, I have not had a situation where the mast pulls very far forward because of the tension to the back from the main sail. With the side stay going to the ama handles it also provides a little pull toward the back of the boat.
Also I have a bit of fear running downwind with too much sail out in stronger winds. Partly because of the risk of the nose diving, and partly because most of my sailing has been on a dingy where the boat became much more difficult to control in a downwind run.
With my limited actual water use, so far, I am feeling my set up fits my sailing style.
...mark...

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...mark...

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

Mark:
I think you are correct about the addition of the side stays especially with the genoa (I ran a 30sq ft jib for several years, and always worried about the side force (one of the reasons I converted to a wing type sail instead (almost no side force on wings))

If you look at this video at 10 minutes in you will see my mast flexing to one side almost 3 ft at the top when running my upwind spinnaker (kind of like a genoa), this can't be good (lol)
https://www.youtube.com/watch?v=CLfQmIKm2MQ


Frankly I had ran side stays a few times, but they limited the ability of the main to bend and spill excess air, so I removed them. It never dawned on me to add bungy's to the side stay lines so you can have your cake and eat it too........

I'm probably going to put side stays back on my boat (with the bungys), I think it's a great idea. Can't think of any downside right now. I will likely attach the side stays near the front of my mast topper (where my current jib attaches) vs the centerline of the main (don't know why yet, but I'll let you know if it works).
The problem I always have is the complexity on my boat keeps going up, which can greatly extend rigging time. Unless something is critical to function, and I just can't get by without it, it gets taken off my boat pretty quickly (the main reason my spinnaker has just sat in the garage for the last 3 yrs unused). Took to long to rig, too many extra lines, and as little as I used the darn thing, it just wasn't worth bringing along.
Anymore my criteria is if it takes me longer than 15 minutes to get the boat ready for launch from when I backup to the water, till I pull away,,, it's not worth the extra effort.

FE
FE

Bob, it is funny how we are all sop different... I find the rigging and derigging exercise to be like savouring a fine wine. I take my time, and check everything out closely, making a mental note to look into something needing attention in the future, and when I back the trailer in, I walk the TI to the nearby sand, secure it, and park the car.

Stepping on board completes my little routine, and I am mentally and physically psyched up to have a great tim,e. I just wish my spinnaker kit wasn't on back-order!

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Tony Stott
2012 Tandem Island "SIC EM" with Hobie spinnaker

Had a chance to test my downwind speeds with the main, the main with barber hauler and the main with Spinnaker. The winds were 15-16 mph and I was on a broad reach. Below are the maimum speeds achived. Average speeds were less by about 2 mph.

Main Only- 7 mph
Main with barber hauler- 8 mph
Main with Spinnaker - 9 mph

Forgot to test barbered main with jib. That would have been an interesting result. Becasue the barber hauled main sits so far out, I suspect it may cancel the jib out on a broad reach.

The spinnaker actually lifted the bow up noticably and I was not nose diving at all. I would nose dive occasionally with the other combinations. Broke a rudder pin that's a rare event for my boat so lots of rudder pins will be stowed away just in case. I normally would not use the spinnaker in those kind of winds. I'm just being impatient about waiting for lighter winds.

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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

On my boat, the side stays pull pretty hard as evidenced by bent steel, so my guess is that the top of the jib will be pulled into the wind.

I am curious how it will work for you.

I hope to be in the boat in about 10 hrs, so hope to learn more.

...mark...

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...mark...

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

Tony Scott said something the other day that has really helped me maximize the power in my jib so I wanted to share it with those using one. The comment was that you want the sheet to pu equal tension on the foot and the leach.

Well, that finally answered a question I have had for a long time- where on the boat should the jib sheet be attached and pull from. I released the jib from the self tacking traveler and added a sheet and started to experiment. It turns out that if the line is directed right to you butt, you have the perfect angle. There is a noticable addition of power at this angle and as I relax the sheet for other points of sail, it remains the perfect angle.

This angle eliminated my luff curling back like would often happen when on an extreme close reach. The sail shape stays perfect now. Its made such a difference that I not sure I'll go back to self tacking taveler. It allows me to eliminate the self tacking lines and use the spinnaker sheets for both spinnaker and jib with a quick release. In the AI, there is a eye post and a mini cleat right near your butt and I can just take the spinnaker sheet and put them over these which directs the lines perfectly.

This forum is such a great source of information.

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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

Gregg, I would add a slight rider to that sheet tension advice.
In stronger wind, lowering the sheet slightly will open out the leech, depowering the sail.
Conversely, slightly raising the sheet will tend to close the leech slightly, generating more power.

Both of these adjustments are quite subtle, and it could be argued that on our relatively unsophisticated boats,. hardly worth the complexity, but you can experiment by pushing the sheet up or down with your paddle to see the effect.

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Tony Stott
2012 Tandem Island "SIC EM" with Hobie spinnaker

Tony is right, that's why big boats have jib tracks to allow adjustment fore and aft while underway (racing). On many boats, there are different tracks for different sails (most monohulls carry 3 jibs). Some even have curved tracks. On monohulls the outboard sheeting tracks are typically further aft for accommodating the bigger jibs (genoas).

While splitting the clew angle is usually a good "first effort" at finding the correct fore/aft sheeting position you can usually find some better position with practice. A LOT depends on how the sail is made and what entry angle the sailmaker used for the jib. For example, when I make a crosscut sail, the best sheet point tends to be further forward than the actual split clew angle spot...if I make a radial head sail, it tends to be best a little aft. If I make a flat sail (very little camber and tight entry angle for pointing), the best sheeting is usually way back.

With these tiny boats and tiny headsails, your sheeting spot won't move a lot, though. Where big boats move 6 inches to 6 feet; these boats will move 1 inch to a foot at most for the best spot; so suggest try splitting the clew angle will get you really close.

You folks might like to see my triak in action after I modified the amas to double their floatation. It allows better use of the sailplan with the big winds I usually sail in...[youtube2]https://www.youtube.com/watch?v=4yd6Rxhh-7g[/youtube2]

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

All the advice is greatly appreciated. Today I was out in higher winds 16mph with 21 mph gusts. I found that the best way to sail upwind with such high winds, was to set the jib and leave it. Then I took the uncleated main sheet in hand and just made moment to moment adustments with the mainsail completely out, dumping wind as needed. If the winds died for a moment, i would just pull back on the mainsheet. Worked great. I never reefed either sail and never felt at risk of capsizing, only focusing on the mail. No need to fear the gusts any more using this method.

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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

Tpdavis473, the bigger outriggers look like they're working well. I experienced that same improvement when I switched out my AI amas for the TI amas. I'm sure the AI2 owners feel the difference as well. You feel more secure throwing up more sail in higher winds. End result was more speed.

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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 have had roughly 10 hours experience with my jib now, over a two day period. My wife and dog were on the boat with me almost the entire time.

Wind conditions: I took several readings during that time with average wind speeds generally between 2 and 4 knots. One stretch during the windiest time produced a 7 knot average with a maximum gust of 8.6 knots.

My evaluation: With my 44 sqft jib and main fully exposed in the strongest winds, I was getting more sideways pull on the mast than I was comfortable with. Partly furling the jib provided a greater margin of comfort. I wish I would have done a little better calculation to further tighten the side support lines to further limit the sideways movement of the mast. In less than 7 knot winds, the side support lines did their job nicely. In the 7 knot average time I was sailing close hauled with minimal luffing on the main sail, none on the jib.

In the lower winds, it was sure nice to have the jib. A couple of times I furled and unfurled the sail and noticed the immediate difference in ‘horsepower’.

I did a little running with the wind, though had the chance to do so only in very light winds. With the jib directed to one side and the main to the other there was a lot of sail space area. The telltale showed there wasn’t much difference between the speed of the boat and wind. The sail area was impressive.

The furling mechanism on the jib worked flawlessly.

Rope management was a little more of a pain than I expected it to be. I need to make a few modifications to simplify rope management. I tied telltales to the mast topper assuming they would nicely flow back. They got tangled in the mast topper. No danger, but a bad choice. If anything has any chance of getting tangled, it will.

Setup took too long. I was definitely not efficient in getting it setup. Though with more experience and some simplifications, I can obviously reduce the setup time, I realized that there are going to be no jib days and jib days. It will not only depend on the wind situation, but on how much time I will have on the water, who I am sailing with, what I want to enjoy or accomplish that day, my mood that day…

Should you install a jib on your tandem island? If the choice is a jib or a spinnaker, for me the choice is easy. Go with a jib. Disclosure: I have never sailed with a spinnaker so I am not a good person to judge. Also my jib experience is very limited. If you just want to get on your Island and enjoy the day, I would say the difference in enjoyment factor isn’t worth the time or effort. If you enjoy tinkering, experimenting, learning, playing with extra ropes… by all means, it is quite a lot of fun.

...mark...

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...mark...

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

Jibs won't improve your boat's performance dramatically on any point of sail. So, for me, the choice would be the spinnaker because a spinnaker does dramatically improve your boats performance on a broad reach or run. I do grant you that you already spend 2/3 of your time going to weather so even a minor improvement in getting upwind might be worth it. Of course, I probably feel that way about spinnakers because I've noticed over the years that people who fly spinnakers tend to be better sailors than the weekend warriors on the water.

I can't emphasize how much I agree with the last statement...folks who just sail their boats are missing out on half the fun IMO.

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