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Board leash for wave riding

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Silver Bullet
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Board leash for wave riding

Postby Silver Bullet » Mon May 10, 2010 6:30 pm

Here's a leash I made for myself and used a good bit last winter in large waves. Thought is might be good for a look and comment, or someone else might like the idea for themselves.

It worked really well and was quite safe. The spot I was riding has a very dodgy inside wind, with a wind shadow and side-off at times. Kiters lose boards from time to time as kites go down and can't be relaunched due to lack of wind on the inside...

The leash part is made of webbed tubing with a thick bunjee inside. It has a little give but doesn't snap back.

The part that works really well is the "fusible link" part of the leash. Nylon zip ties are bunched on the ring that attaches to the harness extension. The harness extension goes to a rope on the back of the harness, and allows the leash to freely move left/right on the back of the harness, depending on the direction of travel & stance.

When riding, I connect to 2 or 3 of the zip ties with the metal snap. If the board is caught by a big wave or other extreme stress occurs, the ties break and the board is released. No extreme force can occur that puts too much stress on the leash plug, or the harness.

If the link is broken, I chase the board down and reattach to a few more of the snap ties, and continue the session.
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board leash small.jpg

ronnie
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Re: Board leash for wave riding

Postby ronnie » Mon May 10, 2010 7:07 pm

I dont understand the thick bungee. Surely it creates a lot of springback when extended?

The webbing takes the force, so I would have thought you would use a very light bungee just to shorten the webbing so there is very little springback and rely on the rope handlepass to give a little to absorb the shock - or does the shock break the zip ties prematurely?

Don Monnot
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Re: Board leash for wave riding

Postby Don Monnot » Mon May 10, 2010 7:10 pm

Keep it simple! I like it. I assume you use pretty thin zip-ties? Have you had them break yet to release the board during a major "oops" when they needed to? Just curious about how much load it takes to break a small zip tie. I haven't tried to do that, but the simplicity (and safety) are very appealing. Having the metal clip stay with the board (and not come flying back to you) is obviously very important. Nice design.

Don

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kitezilla
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Re: Board leash for wave riding

Postby kitezilla » Tue May 11, 2010 3:43 pm

Below are listed 3 recent threads which discuss most aspects of the construction and use of a short board leash in surf kiting. There are many members of KF who see a need for the use of a board leash in certain situations. In the past 6 years, I have paid attention to the comments of the members interested in this subject, and have arrived at a design for such a leash. I have discussed the components of this design in the threads listed below, and have included a picture of the leash, that I have been testing in both small surf and flat water.

The one thing that I like about your design, is the fact that the row of "Zip-ties", located at the harness, allows the rider to easily hook his leash back up, after an incident, where the board was torn away from the rider. In order to hook the leash back to the harness, with my design, the rider needs to do some prior training to develop the skill to hook the "automatic mushroom push away release", using only ONE hand. The requirement of "reassembly by the use of only one hand" is a very important component in the design of any board leash. Also, the fact that your "Zip-ties" are located at the riders hip is a very good design, in that it allows the rider to grab the floating leash and not the board, in order to do the reassembly of the leash.

As far as the question about what size "Zip-tie" to use, for the proper amount of release-force... I have experimented with this, and have concluded that a good compromise force is around 100 pounds. "Zip-ties" are rated in pounds of force... 10...20...30...etc. So, the use of 2 "Zip-ties" each rated for 50 pounds of force, will achieve this goal. In order to achieve this amount of release force for my surf leash design, I have created a "fuse" that automatically and consistently releases the leash at about 90 pounds of pressure. I have discussed the construction of this "fuse" in one or more of these threads, but if anyone is interested in more detail, just say so, and I will expand on the construction detail.

One suggestion, which would improve on your design, would be to incorporate 2 quick releases (one at each end of the leash), so that when you get rolled in the surf, and the leash wraps around your body (which it will do often), then, you can release either end of the leash...letting just the board go loose, or letting the whole leash and board go loose. You can see these 2 releases in the picture. I have tested the leash in both surf and flat water, and have been glad to have had both of those releases, along with the automatic force calibrated release.

Having a very thick leash, that the rider can feel as it wraps around the riders body is an important component, and your leash has this characteristic.

One other improvement to both your leash and my leash would be a large yellow float, located at the harness end of the leash, which would guarantee that the loose end of the leash would float, and be visible in the surf, allowing the rider to more quickly and easily locate and grab the end of the leash, prior to reattaching it to his harness.

Anyway, keep up the good work, and maybe we will arrive at a fairly safe, reliable, and practical leash design, even though leash-less will probably always be the safest way to ride.

Board Leash Attack:

viewtopic.php?f=1&t=2363763


Board Leash In Light Wind:

viewtopic.php?f=1&t=2363829

Surf Leash Length:

viewtopic.php?f=1&t=2361940
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FredBGG
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Re: Board leash for wave riding

Postby FredBGG » Wed May 12, 2010 12:52 am

Hey Silver Bullet.

Be very carefull about using a board leash in the surf....it can be very problematic.

Today I was out in strong gusty wind riding a 6m and strapless surfboard.
Waves were very agressive wind swell mixed with ground swell.
Twice this morning I got tumbles and may board once went over my lines and then I flew over the board. If I had had a leash it would have been wrapped around my lines.
A second time my board actually stuck it's nose right into the lines.
The more fun you are having in the waves the more this type of thing can happen.

Now even without the board flying over your lines.... if you do decide to go with a leash you need a design that will snag your lines as little as possible. The way you have things setup there are far to many snag points, and the snag points will be behind your back.

In the waves there is always the risk of being pushed into your lines or the board getting pushed into the lines. Getting out of these situations is tricky even without the added problem of the leash.

However I noticed that Mitu Motero uses a surfer type leash. The fatter and somewhat ridged leash plastic is probably easier to get at and being very smooth has less line snag risks.
The palstic leash also has less drag in the water that webbing etc...
His local spot Ponte Preta is full of rocks and has offshore-ish wind.

I also find that a board leash can get in the way when you are trying to get back on the board very quickly.

One more thing...I think it is important that the leash design lets you cut through the leash with aline knife if you need to,

There are many times when getting away from your board in the surf is a good thing.

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Re: Board leash for wave riding

Postby ronnie » Wed May 12, 2010 8:48 am

There's a photo of a 1.2m waveboard leash in this thread.

viewtopic.php?f=1&t=2350471&start=50

My OR Session harness has a plastic covered handlepass line across the back, with a Q/R for it at the side of the harness. For something like that, it might work to tie the board to a floating leash made from 1.2m of 4mm polythene rope inside 6mm polyethylene tube, with a pipe clip like this on the harness end. The idea is that you choose the clip size to give you the required release load, and if it opens, you can reconnect it by pushing it back onto the handlepass line and clip it shut again. Might be worth putting a float ball on the leash near the clip to make finding it easier.

After some use, the clip would release easier, so it would probably need replaced then, so might be worth buying a few.
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Re: Board leash for wave riding

Postby kitezilla » Wed May 12, 2010 4:02 pm

FredBGG wrote:
One more thing...I think it is important that the leash design lets you cut through the leash with aline knife if you need to,

There are many times when getting away from your board in the surf is a good thing.
Good point Fred...A kiter should always have a "plan B" and "plan C". However, I used to have the hook-knife line cutting plan as "plan B", but after doing the study on line knives (see the thread
"Hook Knives...don't bet your life on them!" ( viewtopic.php?f=1&t=2343820 ), I have relegated the the knife idea down a notch, from 'plan B" to "plan C". From the above picture, you can see that there are 4 options for turning the board loose, in case of a problem like the ones you have described in your post. I can disconnect the whole leash at the harness by (1) disconnecting the 'slide-gated shackle' or (2) releasing the whole leash using the push-away mushroom release. The third way (3) I can release just the board is to use the slide-tube quick release located at the board end of the leash...and the forth way (4) to release the board is to use "plan C" and use the hook knife to cut the kite line that secures the leash to the board.

On a related design issue... note that the use of the piece of old spectra kite line, that is used, is tied to the fin bolts in such a way as to assure that the pull on the board leash is directly on the center of the end of the board...minimizing the tendency for the pull of the leash on the board to encourage the board to 'fish-lure' or 'tomb-stone'. This is an important design point, so that the attachment point of the leash on the board will not cause the board to dive or act erratically, as the board is being pulled through the water behind the out-of-control kiter. The board will tend to follow the path of the kiter, without engaging random vectors of force, which would result in unpredictable pulses of force on the leash and the kiter. The kite line (securing the leash pigtail) is positioned so that there will be some tension on the line, allowing the hook-knife to more efficiently cut the line, as the hook of the knife slips between the line and the board. This solves the problem of trying to cut a free-floating and easily movable (and escapable from the knife) line. Below is another picture of the way the piece of old kite line can be tied to the fin bolts on the top of the board and on the bottom of the board, resulting in a "V" shaped design, again, allowing the pull from the leash to originate at the center of the end of the board. I don't feel that the resistance of the old piece of kite line is significant to the performance of the board. I also feel that the trade-off of having a thick and easily located and non tangling leash versus having a thin leash line, that could be cut with a line knife at any point along the line...is a good trade off, since the thick leash can be more easily located and handled in a "mummy wrap" style emergency.
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Re: Board leash for wave riding

Postby kitezilla » Wed May 12, 2010 4:44 pm

ronnie,

I am always impressed with your innovative potential solutions to problems. I hope you will do some force-testing to see if that pipe clip has the right properties for use as a "fusible link"... to answer such questions as:

(1) will it release at a designated force?
(2) will it release consistently at this force?
(3) will it have longevity?

Also, can it be snapped back together with only one hand. I feel that everything that is to be used in an emergency, in kiting, should have the property of being able to done with just ONE hand. The remaining hand is always needed for some kind of "control." of the equipment, or so it seems.

Also, while I am handing out compliments, I want to acknowledge your insight into a significant problem in designing a board leash "breakable link" or force calibrated "fuse", as you posted the following in the thread:

viewtopic.php?f=1&t=2363475

You said: "The problem is though - if you set it strong enough to keep your board attached when it is passing through a wave, its going to be strong enough to bring it back at you if it is not sunk in the water to start with."

So, in designing a board leash "fuse", one must compromise and hopefully... err on the side
of safety rather than on the side of board retention under all conditions. I have settled on the compromised force of release of about 90 pounds, based on repeated tests of forces from 20 pounds up to 90 pounds. I would guess, however, that at times, and under some circumstances, I would not want the board to release at even 400 pounds of force, but I don't see any way to achieve both of these results.

My last compliment and "shout-out" goes to the KF member Kamikusa for his clever suggestion on how to make a "calibrated tension automatic board leash release". The one I have made and tested continues to work very efficiently and effectively. The following picture shows the tensioned release mechanism, using 9 warps of 1/8th inch bungee, to achieve a release force of about 90 pounds tension, at a stretch distance of about 5 inches, where the 'pull-string' disengages the mushroom quick release.
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ronnie
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Re: Board leash for wave riding

Postby ronnie » Wed May 12, 2010 10:44 pm

Thanks Zilla,

I dont ride waves with a kite, so there's no point in me deciding if the pipe clip works. It depends what you are clipping it round as to what force it releases at and how easy it is to clip it around the line again.
It looks like it could be done with one hand, underwater - if you had practiced it.

It was the best thing I could find for a one handed solution. It might be the right force in a certain size, or it might be that you could narrow the clipping part to reduce the release force. I would do that by cutting a bit off each end of the cylindrical part on the right, that clips into the slot on the left.

I have made floating leashes from that rope and tubing I mentioned. That makes a good stiff leash that is less likely to get wrapped on something.
Last edited by ronnie on Thu May 13, 2010 12:22 pm, edited 1 time in total.

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Re: Board leash for wave riding

Postby tautologies » Wed May 12, 2010 11:10 pm

I am in general not a fan of of board leashes, but I understand they can be necessary sometimes.

What I don't like is the breakaway plastic. Doesn't really matter that it doesn't break often, the solution is not sustainable. It litters the reef, and it never disappears. Make your breakaway solution with something that doesn't mess up mother nature. :-)

a.


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