On-the-bar trim toggle

[rynhardt]

I've been looking for a more user-friendly trim system, for a while now. The problem inland is the gusts/lulls are very short-lived. I might be fine on on tack, then overpowered on the next tack, and fine again on the next tack. By the time I've sorted out the trim, conditions have changed again. So recently I've been using no trim system at all, and it's great 80% of the time.

I've dabbled with the idea of rear-line trim adjustment, but the solutions appear to be complex and somewhat underwhelming. Front-line trim systems appear simpler but have their own issues.

Then I came across this thread "Zeeko ultimate bar no clamcleat no depower straps?"
viewtopic.php?t=2374213

And especially the mods that faklord, Telekiter, tomatkins and others have made.

The Zeeko UDS trim system, which is apparently an implementation of the Z-drag system (thanks tomatkins), seems to work pretty well. Once set, the trim remains stable under load. Pulling one or the other line then allows you to adjust the trim. But you still have a fixed point on the line (either below or above the bar) where you need to make the adjustment.

If all you need to do is grab hold of the line somehow to be able to move it, why not put a releasable clamp directly on the bar? Then simply grip the rope and push or pull it to adjust the trim.

Without having to move your hands off the bar. With immediate and fine-grained effect.

From this my little trim toggle was born. A simple C-shaped wire loop that fits around the bar, with the rope threaded through it, and a small stopper ball to provide grip.

When released, it simply slides along with the bar over the rope. You can still sheet in/out and steer as per normal.
But grab it with your thumb and you can grip the rope between the toggle and bar.

Push out to depower (shorten trim line). Pull in to power up (lengthen trim line).
Or put the toggle on the other line, and now you can pull to depower, push to power up. Your choice.

Ideally I'd make the little toggle out of 4mm 316 s/s wire and put a nice red stopper ball on it, but I haven't gone shopping yet.
And I haven't tested this out under real conditions.. But I am excited about the possibilities!

As always, your feedback is much appreciated.

Short vid on how the trim toggle works.


Short vid on the setup.


And some pics, of course.

[ronnie]

What is the safety system?

[rynhardt]

What is the safety system?

You let go of the bar

Seriously though, long depower throw on both front lines kills 80% of the power. If I need single line flag-out, I hook my leash into one of the front line rings (discussed elsewhere).
And the mushroom is the kite release.

But this post is about the trim system, especially for those who are running a version of the Zeeko UDS or Z-drag trim system.

[Kamikuza]

Clever, I like that. I wouldn't like haven't to sheet in or out to trim though...but that's just me!

[norcom]

Neat idea but wouldn't it jam if you loop the kite? At least until you spun the bar around the other way?

[tomatkins]

rynhardt,

Thanks for reawakening this topic. I like your idea of getting a "good grip" on the spectra line, in that... my experience with making the adjustments, using the "Prusset Ball" line gripper, was that the biggest problem with the device was "slippage". This lack of positive grip on the line only occurred when I tried to "depower" the kite, where effort was to shorten the power line and draw the front lines in, so that the angle of attack of the kite became flatter. There was no problem "powering-up" the kite, because the line slipped easily in the direction of lengthening the front lines.

So, your invention of grasping the one power line to power up the kite is a good idea, in that the kiter is able to use both arms to pull on the bar, and exert a lot of force in the adjustment line.

You have "broken the ice" on this idea, so the rest of us can add to the exploration of this idea...I will go first:

Maybe it would solve some of the problems that kiter would object to, like the idea of not being able to grab the bar with one hand, splitting the fingers around the power line, and the spinning of the bar, as noted by a previous poster. So, I think that the use of a bar like the Core bar where the 2 power lines are separated, along with the use of a swivel, would solve both complaints. Image a short piece of pipe (5cm) that could slide on the bar itself, located adjacent to one of the holes through the bar... and this sliding pipe would be somehow able to grab the one line... and as the kiter pulls the sliding pipe toward the end of the bar, the one line is grasped and held in position, and therefore, as the bar is then, pushed or pulled... the line is adjusted.

This sliding pipe idea would allow the kiter to "split the fingers around the power line" and not stick up, in the way, like the ball, you have shown.

Nice prototype to test the feasibility of your idea. Thanks for posting this idea.

[rynhardt]

Thanks for the feedback, guys.

@norcom: You could easily add a swivel on the harness side, as tomatkins said.

@tomatkins: A sliding option presents difficulties in term of friction (over rubbery handlebar) and potentially sand jamming it. You also need a bit of leverage for your thumb to hook into. I think you could just put the toggle ball on the backside of the bar. Your thumb will still be able to get a good grip, but it will stick out between your fingers, and not be in the way of your palm. Alternatively you can keep the toggle ball on the front and just grip the bar from the back, when you want to grab the centre of the bar.

Regardless, I think there is scope for exploration into different ways to grab the rope using a mechanism integrated into the bar itself. The trim toggle I proposed is just one way, and it is a retro-fit onto an existing bar.
However, a bar designed specifically to grip the rope may provide better results. For example, a releasable cam cleat built into centre hole itself.

[tomatkins]

If the bar has TWO holes, rather than one hole for both ropes, then a device that will grab the rope could be more easily designed to temporarily "jam" the one rope.

You could even place the link to the engagement pinching mechanism (ie. string, rod,lever, etc), at the end of a hollow bar.

[rynhardt]

If the bar has TWO holes, rather than one hole for both ropes, then a device that will grab the rope could be more easily designed to temporarily "jam" the one rope.

You could even place the link to the engagement pinching mechanism (ie. string, rod,lever, etc), at the end of a hollow bar.

That is an excellent idea.
You could have a flat bar, say 5mm x 20mm x 500mm, with the 2 rope holes in the centre, running through the length of the bar. Then have a handle each side on the bar ends. You can then pinch either of the ropes and decide whether to pull or push to adjust the length.

I'll draw up a diagram tomorrow...

The bar still has one oblong hole, but the inner sliding bar with 2 holes will jam against the sides of the outer hole. Or I suppose the other bar could also have 2 holes if the inner bar has slots rather than holes, so only one rope gets jammed at a time.

[rynhardt]

Here's a quick animation, showing some kind of handle on the bar ends, with a movable center with two slots. Depending on which bar end handle you pull, you can clinch either of the two ropes.
The animation shows a cut-away view for clarity, and is just a rough draft to demonstrate the principle.