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PostPosted: Wed Mar 20, 2013 8:35 am 
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Agreed. It's like I can't just ignore it and it plants the seed of apprehension that it is a point of failure. It's fairly unsettling over the course of a trip. If you can resolve it this way it is one less thing to worry about constantly.

For a quick release I was thinking perhaps threading (with loctite or epoxy) a wider SS bolt up through the existing hobie bung, and locking the top down with a wingnut. Perhaps a rubber washer between to allow some torque?

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PostPosted: Wed Mar 20, 2013 8:53 am 
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yaknrugger wrote:
It's like I can't just ignore it and it plants the seed of apprehension that it is a point of failure. It's fairly unsettling over the course of a trip. If you can resolve it this way it is one less thing to worry about constantly.


I think we have to be careful about overstating the issue. In general, and by that I mean virtually ALL Adventure Island, or Tandem Island users, never experience any problems with the current system to attach the amas. Certainly any kind of debilitating failure is extremely rare.

Is there potential for a better system to be built? Absolutely. But the current system isn't something that people should be worried about when out on a trip. These boats have been proven to be very safe.

As I stated earlier, I'm very interested to see what becomes of this idea, but let's just realize that this is an attempt to improve a working product, not an attempt to fix a faulty piece.

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PostPosted: Wed Mar 20, 2013 9:32 am 
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Right, note my opening statement in the video - the bungee system works just fine for 90% to 95% of Island users. My intention was only to come up with something that might work better for those who use their boats beyond what Hobie's intent for the Islands has always been.


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PostPosted: Wed Mar 20, 2013 9:35 am 
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augaug wrote:
As I stated earlier, I'm very interested to see what becomes of this idea, but let's just realize that this is an attempt to improve a working product, not an attempt to fix a faulty piece.


I never said there was an issue. I actually said the bungees are proven and safe provided they are serviceable. My point was with the amas slapping about that there is a perceived problem, as if something is just not quite right. This isn't just me, it's anyone who rides on my TI as well as my friends that own them. I reassure them everything is fine, but as am I the whole ride they are paying attention to the constant slapping of the amas.

I will make the analogy of a ceiling fan. I have been in a room where they are not perfectly balanced and flailing about, making noise, etc. While it may never fall out of the ceiling you can't sit in the room with it and not imagine it being possible. On the other hand, a fan that is balanced and secured tautly to the ceiling goes unnoticed, thus not causing one to imagine it could fail or better yet to not notice it at all.

The last thing I want my passengers thinking about while out having fun is the ama ripping off even after I've told them it's highly improbable.

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PostPosted: Wed Mar 20, 2013 9:39 am 
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I agree with Augaug.

If you do not disassemble your AI/TI, but rather fold the amas for trailering, you are putting stress on the bungees. I trailer, but need to disassemble my aka/amas, so that bungee stress is removed. The bungees on our 2 AIs seem as good as new; however, I am going to set up a double bungee system because of comments made here and elsewhere.

Tom, your idea is interesting. A few things come to mind, if I were doing it. (1) Quality control on the plastic fastener--how would I know the plastic would not break, perhaps easier than the bungees. (2) It would have to be a plastic which would not suffer sun damage. (3) I would try to find a screw with a wing nut type head so it could be put in by hand. (4) I would worry that the screw might come loose, especially on a long day out.

The recent catastrophic accident that Pelican & his son had in the 2013 Everglades Challenge very likely was due to a broken bungee cord on the front aka connection. It appears that the bungee may have been over-stressed when assembling the boat and [I think] broke in difficult sailing conditions. I can imagine a situation where there could be downward pressure on the ama. For example, say you are sailing at high speed with a fully loaded boat as is common in the Everglades Challenge. Your leeward ama is being buried under waves regularly. At some point, with your ama buried, the hull tries to ride over a wave, i.e., the hull is rising up, but the ama is buried beneath a wave and can't recover quickly back to the surface. Under these conditions, the bungee may suffer stress, and if it were already stretched to breaking, it could break and the ama come off the aka.

For now, I like the double bungee idea, although with some development, your idea, Tom, could prove the most fail-safe.

Keith

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PostPosted: Wed Mar 20, 2013 9:51 am 
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yaknrugger wrote:
My point was with the amas slapping about that there is a perceived problem
Yeah, that's fair. These are unique boats, and I can see how some differences in these boats can cause people to worry about things that they perceive to be a problem.

I only put my two cents in because once something is online, it stays online for years (forever?) and this is the type of thread that, if read incorrectly, can cause these boats to develop an unfair, bad reputation.

There is nothing in these boats that is unbreakable, and as with any other craft, heading out on the water requires awareness. I just hope to clarify that being aware and being worried are two very different things. If you're prepared to head out on the water for the day with a Hobie, you shouldn't worry about things unnecessarily.

Chekika wrote:
At some point, with your ama buried, the hull tries to ride over a wave, i.e., the hull is rising up, but the ama is buried beneath a wave and can't recover quickly back to the surface. Under these conditions, the bungee may suffer stress
This is exactly the scenario that I imagine when I picture the current bungee system being stressed. I've been out in big waves in Lake Ontario, and never experienced a problem at all, but any system that can keep the ama up tight in more extreme conditions while still allowing folding and quick release of the ama sounds great to me.

When I had my AI, I also rarely folded the AI for a long time, I would always disassemble the boat. I can see a TI owner sitting the boat folded for extended periods of time, and you'd think that over a matter of a number of years that the bungee may lose some elasticity. That's why I'm interested in this idea.

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PostPosted: Wed Mar 20, 2013 10:04 am 
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The plastic I used is a high grade material that is highly resistant to UV and fatigue damage. Probably much more so than the plastic used to build these boats.

Can it be guaranteed not to fail? I don't think anything is 100%, and certainly the bungees themselves are hardly anything more than rubber bands, made who knows where, by perhaps various companies at various times. All I can offer is that I trust the plastic I used more than I would trust the bungees, particularly in very demanding situations. But I won't give anything a 100% certainty rating.

One item brought up that begs an answer - what happens when you have an Ama buried and the boat needs to come up quickly on that side? Does the bungee, or my retention piece, have to pull the Ama up? Well, take one of your Amas off and try pushing it under the water (it'll take 2 people to even come close to doing it. You'll most likely need 3 for a TI Ama).

The Ama is pushing "up" with quite a bit of force. It doesn't require being pulled up to the surface and if you wonder about the actual time involved in having it "float" back up to the top, try the above test and see for yourself. From a foot underwater it shoots back up top in a mere split second and with great authority. I really can't see a bungee nor a retention hasp breaking or failing in this instance. The applied force is still "up" against the Aka collar, not the bungee or retention hasp.


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PostPosted: Wed Mar 20, 2013 10:05 am 
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augaug wrote:
I only put my two cents in because once something is online, it stays online for years (forever?) and this is the type of thread that, if read incorrectly, can cause these boats to develop an unfair, bad reputation.


You are right on here augaug. Agreed. I want to go on record by saying the bungees are more than adequate for ama retention to the akas.

I am highly interested in this thread because I want to get rid of the annoying slapping in chop. I am also very interested in the possibility of redundancy with the bungees.

Here is my submission for the layers. A larger SS bolt threaded (and loctite blue?) up through the existing bung, rubber washer, Tom's plastic blank, another rubber washer, bungee retied or somehow fitted to bolt, SS washer, SS Wingnut. Hmm, how to fix the bungee securely to the SS bolt without getting worn from rubbing?

All of the benefits, redundancy, and best of all no slap.

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PostPosted: Wed Mar 20, 2013 10:09 am 
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You could use SS eye bolts for that matter, which would retain the plastic hasp and allow for attachment of a bungee. But frankly I just don't think the bungee is anything but dead weight at that point. But if you want to, it wouldn't be hard to accomplish.

My effort now is to make the retainer simple enough that no screws or bolts are needed. I know how to do it, I just need to make a fastener part.


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PostPosted: Wed Mar 20, 2013 10:15 am 
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Tom Kirkman wrote:
You could use SS eye bolts for that matter, which would retain the plastic hasp and allow for attachment of a bungee. But frankly I just don't think the bungee is anything but dead weight at that point. But if you want to, it wouldn't be hard to accomplish.

My effort now is to make the retainer simple enough that no screws or bolts are needed. I know how to do it, I just need to make a fastener part.


I agree it won't be needed as well, but there is a silver lining to the SS eyebolt. It is something you can manually secure by hand and those wanting the redundancy to sleep better can clip the bungee to the eyebolt.

Simple. I will now keep quiet and wait to see the no screw/bolts solutions Tom.

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 Post subject: Larger diameter bungees
PostPosted: Wed Mar 20, 2013 10:51 am 
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I like your idea! Where I sail, chop is nasty...up to six feet high, and it almost always whitecaps. So the Amas were always bouncing up and down. The original ama bungees on the TI were quite small diameter, so there was a lot of stretching going on. The thin bungees were easy to pull on and off...but that was also the problem with the stretching allowing the amas to almost come out of their sockets. Hobie makes a larger diameter plug and bungee, which is much stronger in its pull. However, the pull is hard on my fingers, especially after a long sail with my fingers getting soft.
I may go with your idea of the HDPM lock. However, I would use a stainless thumb bolt. You wouldn't need a screw driver or leave the bolts so loose that they might come loose.


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PostPosted: Wed Mar 20, 2013 4:20 pm 
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If you made the plate itself out of aluminum, I might give it a whirl.

Plastic fender washer under the plate.
Stainless 1/4"-20 eyebolts screw it down.
Clip a bungee to those for us "optimists" :wink:

Just don't lose the hardware.

For the record, Yakass's double bungie system, the way we use it, eliminates Ama slap on the AI/TI/TI3. Using weak (single) and degraded bungees is the real issue.


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PostPosted: Wed Mar 20, 2013 4:45 pm 
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I like the idea of the HDPE retainer plate being secured by SS ring-bolts, which can then also house bungees for belt-n-braces.

BTW every time I put my TI on its trailer, I release all bungees and cleats as well as open hatches. It hardly takes any time, and my bungees are only in tension when actually in use.

Also, my tests show an AI ama requires downwards force of about 100kg to be pushed under water, while a TI one requires 150kg.

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PostPosted: Wed Mar 20, 2013 5:30 pm 
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Your unique design has certainly sparked some debate from the brainstorm committee Tom which is great. Personally, I'd prefer the idea as a backup rather than a replacement. If a bungee fails, then your retaining plate comes into play ( or visa versa ).

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PostPosted: Wed Mar 20, 2013 7:13 pm 
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With the retainer in place, the bungee can't fail because it's no longer doing anything.

If the retainer fails, then the bungee would indeed take over, but then it becomes a matter of how much redundancy do you require for peace of mind? Should the Islands have double hulls in case one leaks? A back up pair of Akas in case one of the main ones fails? A second rudder in case the first one pops? How far do you go to make the Islands 100% bulletproof? What do you give up in return for adding back ups of back ups?

The retainer, as shown, is a heavier duty piece of kit than just about anything else on the AI or TI. And it's not required to do much of anything that puts it under any sort of force or pressure. What I'm trying to convey, is that it's not the weak link in the chain. Not even close. It won't be the thing I'll be worrying about next time I'm on the water. Hopefully my experiences and those who choose to work up a version of their own can eventually put some minds at ease. We'll see.


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