What's with these bolts then?

Not sure I'd like this to be me on my own. https://youtu.be/oJhoExyhWIU. Do I change to steel pins or not?

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Every day is an Adventure Island day

And I bet none of those guys would do it on their own either. Some things need to be done in company, and they also do long multi-night trips along the coast of the Canarys as a group. I am so jealous.

I found the wavering voice of the guy holding the camera "interesting" as he wondered out loud how he would go getting back on his own!

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

I've sailed those water's many times, it's incredibly deep, and the trade winds during the summer are something else. My concerns are my bolts, gets bloody rough at times crossing the Sandy Straits Qld

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Every day is an Adventure Island day

Great video and teamwork!

I've been out in swells like that a couple of times. As long as nothing breaks, the most dangerous things out there, are each other. When surfing down a wave you sometimes uncontrollably head towards each other. And if you stay farther apart, when you are in the troth, you can no longer see each other (even the tops of the masts in over 7' swell).

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Hobie Island Sailing since 2006

I covered this in one of my videos. If you don't want to move to a stainless steel bolt, you can still double the strength of the plastic bolt without completely giving up the sacrificial aspect of that bolt in a collision by acquiring two more aka brace pieces and installing them on the front aka bar so that you have two braces in play on each side. This effectively doubles the force needed to shear the plastic pins, but is still not as strong (unforgiving) as even a single SS bolt.

For the type sailing some guys do in the ocean, this is a pretty good mod for several reasons.

H I Tom do you have a link for your video, many thanks..

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Every day is an Adventure Island day

You can simply strengthen the shear pin. SS Bolts are too strong, too extreme, unless you are certain you will never collide with anything, even a wave at high speed and loaded to the max with people or gear. Use Nylatron pins. No extra braces required. However, I understand the Nylatron pins, about $4/pin in Dec, 2015, are now a whopping $9.32/pin...hummm? That has definitely gotten a bit steep, price-wise. We can make our own easily from 1/4" 6/6 nylon stock at a fraction of the price. I'm going to do it soon.

Thanks for posting that video Roller. Those guys make great videos!!!

Keith

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2015 AI 2, 2014 Tandem

"Any intelligent fool can make things bigger and more complex ... It takes a touch of genius and a lot of courage to move in the opposite direction." A. Einstein

"Less is more" Anon

Where do ya'll buy your Nylatron pin bolts?

Nylatron is a brand name.
If you go to lowes you can buy the nylon bolts you need off the shelf for about a buck, buy as many as you like.
I suggest buying the 1/4-20 x 2.5" or 3" long (make sure the unthreaded shank is long enough to fit thru the hole).
Doesn't hurt a thing having the bottom of the bolt hanging down, you can always nip off the excess with pliers.
Unfortunately doing this buys you nothing at all. It takes about 150lbs of force to sheer the nylon bolt, it takes 200 lbs force to elbow the $200 dollar AKA bar (un-repairable). It also takes 200 lbs of force to rip the little ball on the hull off the hull. And about 200 lbs force to rip the hull itself at the brace attachment point. If you don't believe me just lock the ama out and push on the AMA forward and back, and watch the hull bend in and out wildly.
The problem in not the brace itself,,, it's the location of the aka brace mounted 1/3 of the distance from the joint, all forces are multipled 3x.
It's best to just allow the nylon bolt shear when overloaded (saving you thousands in repairs (as designed)). Just add safety ropes that prevent the AMA's from folding in when the nylon pin does break.
Do what you want, I'm just tryin to save you a big bag of money thats all.
FE

FE, of course, people don't want key parts of their boat to fail, but they also don't want to be dumped into water if a light-weight pin shears when simply hitting a wave. Remember, not everyone sails in warm FL waters. Keep out lines are important, but not everyone has those. The simple first step is a beefed up shear pin such as a Nylatron pin or simply your suggestion of a 2.5-3" long, 1/4" thick, nylon bolt with an un-threaded portion that fits through the shear pin hole (like the nylatron pin.)

When I capsized due to an unepected shear pin break, I lost a couple thousand dollars worth of gear and personal items.

Keith

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2015 AI 2, 2014 Tandem

"Any intelligent fool can make things bigger and more complex ... It takes a touch of genius and a lot of courage to move in the opposite direction." A. Einstein

"Less is more" Anon

Keith:
I'm agreeing with you that a solid nylon pin/bolt is superior and still likely below the threshold sheer strength where it will break prior to the aka bar elbowing, (folding in half).
Here's why....
When doing my testing of the mechanism and systems with my trusty fish scale I could easily sheer a new sheer bolt with a one time swift jerk of 150 lbs. I then tested with multiple jerks with 100lb force, if I remember it took 3-4 100 lb jerks to sheer the pin. I then put in a new bolt and did two 50lb jerks on the ama, then removed and inspected the pin, the threads were damaged and the pin was beginning to deform. I don't recall how many 50lb jerks it took for the pin to finally fail, I think somewhere between 20 and 50 hits. 50 lbs is about the same force as hitting a boat wake at your normal cruising speeds (not my cruising speeds with my highly modified TI (lol)).
I'm pretty sure your solid bolt will not suffer progressive damage. So in conclusion your idea of a more solid plastic pin/bolt is valid and sound, and I recommend Hobie implement the same change, (yea as if they listen to me lol).
I still highly recommend the safety lines because they are simple easy and cheap to implement.
FE
If anyone desires they can do an FEA themselves on the aluminum AKA bar itself, feel free, (I did). The wall thickness is 1/16 on the sides and 1/8 on the top and bottom, if I recall the OD is around 1 1/4" dia. I used 360-t6 alum for the analysis, I highly doubt the actual alum used is that good. The FEA clearly shows the yield strength of the material itself is clearly exceeded. When observing the welded joint itself, the type of weld itself also weakens the structure considerably, making it even more prone to elbowing.
In addition the standard bolt that holds the ball onto the hull, the sheer strength of that bolt is published in any engineering reference, not even mentioning the strength of the plastic hull itself in and around the attachment area. All this stuff is first year engineering, (not rocket science).

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2015 AI 2, 2014 Tandem

"Any intelligent fool can make things bigger and more complex ... It takes a touch of genius and a lot of courage to move in the opposite direction." A. Einstein

"Less is more" Anon

This subject keeps coming up, and each time, attention focuses on the strength of the pin.

The pin strength is perfectly fine IF you add keep-out lines. These lines ensure that if a pin breaks, the ama cannot come slamming in and causing an instant capsize. I believe you need keep-out lines even if you fit a stronger pin.

Do a search on "keep-out lines".

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

Tony:
I agree 100% the keep out lines prevent the boat from flipping when the sheer pin breaks, that's all they do no more, no less. They don't interfere with the original design intent of the original system in any way shape or form. You have about a buck or two in expense and it takes all of 5 minutes of your time to implement one time only. Once mounted on the boat you don't need to do anything else for the rest of the life of the boat beyond stuffing the ropes into the mesh pockets when breaking the boat down, (takes all of 30 seconds). I have had the same exact ropes and clips on my TI for 6 yrs now, obviously they look pretty rough these days.
On my boat anytime I dive the bow and pitchpole, bury an AMA, or hit a boat wake or 2-3ft chop while traveling at speed the sheer pins break as if they weren't there at all. I've sheared off probably 50 to 60 nylon shear pins. The problem is as speed increases so does the water force on the AMA, which increases exponentially with speed. You can verify all this yourself with just your hand. While traveling at normal sailing speed (about 4mph) plunge your open hand into the water, you should be able to keep your hand straight down. Now speed up to 8mph (or in my case 12-15 mph) and try it again, good luck trying to keep your hand straight.
Now get your boat up to speed in good sailing conditions lets say 8mph boat speed, now steer into a boat wake or surf. Pay attention to the noise your AMA makes and watch the motion of the AMA. Now take your boat home and while on the trailer lock your AMA out. Now grab the AMA and jerk it forward or back trying to replicate the same force and sound. Do it 6 times (6 waves worth). If the AKA pin has not sheered yet, take the pin out and look at it, if it looks like mine did the threads will be smashed, and the nylon bolt will be badly deformed (ready to break). Don't take my word for it, try it yourself (I did). Now picture yourself offshore in great winds barreling along in three ft chop having fun. If your shear pin breaks, the AMA will fold in and the boat will capsize, do you want to be out there upside down in 15mph winds and 3-4ft waves (I don't). After your tests on shore you now know exactly how many waves you can hit before failure (a ticking time bomb). Don't take my word on any of this, try it all yourself. IMO I think it's pretty important to know my boats limitations myself. This is why I always say know your boats real (not imagined) verifiable capabilities, you life may depend on it.
Do whatever you want.
FE
Edit: Whenever I pull up on shore, and people see me struggling to drag my 200 lb boat from the waterline, they always run up and say here let me help, they grab the AMA and start pulling. Every single time the AKA pin breaks. I'm sure this has happened to all of us (helpers). Kinda says it all.

Hi;

See also
https://www.hobiecat.com/forums/viewtop ... 70&t=59921