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PostPosted: Sun May 13, 2012 6:29 pm 
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Hopefully I am not duplicating another thread but am in dire need of info (& a fix) for this rivet issue. The new V2 akas are using 4 rivets to attach the aka metal arm to a plastic sleeve which makes up the knuckle assembly which clips into the Xbar. The rivets on the akas of the AI are all loose allowing, in my opinion, a dangerous amount of play.

As with any part under constant stress any play produces a quickly downward spiral where the part flexing can only increase further puling on the rivets. In this case the pressure of the entire ama as the boat heels flexing & pulling the rivets with every wave you hit.

Anyway, I can see using rivets on a plastic collar like that at the end of the aka where it mates with the ama. Or using rivets to attach small plastic widgets that are not under stress. I have a hard time seeing rivets as the "part of choice" to connect such a high stress area like the knuckle to the aka.

So, is there a fix? My idea is to drill out the head of each of the 4 rivets without increasing the size of the original hole and after knocking out the rivet replacing it with a SS machine screw or self tapping screw or better yet a bolt & nut. Understand that nothing is wrong with the aka or knuckle and that the only failure I can see is the 4 rivets.

If I am on the right track, what size screw or bolt is recommended or is there some other was to tighten up what is otherwise a great design?

TIA

Yakaholic


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PostPosted: Sun May 13, 2012 6:48 pm 
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Yakaholic
I think you should post here:
viewtopic.php?f=71&t=42549
:wink:

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PostPosted: Sun May 13, 2012 7:11 pm 
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Thanks Mickey. I found that thread and read through it. Seemed to cover a variety of topics including different sources of aka play and even musing about some "give" being a designed feature of the V2 akas verses the V1 akas.

All good stuff.

When I attach the aka arm (no ama) and move it up and down you can see the excessive play and all 4 rivets wobble like they are stretched and the heads are about to pop off. There is some corrosion on the rivets but the mechanical failure to me is obvious. The bounce even in light chop is scary and I have had multiple AIs since 2006, so I can at least compare this to what I'm used to seeing.

Hobie and all their engineers like Matt Miller have always been extremely helpful in resolving issues quickly and improving the product. I have no doubt they do so yet again.


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PostPosted: Sun May 13, 2012 7:53 pm 
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Anyone here think that adding larger rivets or washers is the answer?


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PostPosted: Sun May 13, 2012 8:30 pm 
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I had 3 akas get loose rivets. I drilled out and replaced them after cleaning out the corrosion in the parts. THese are stainless rivets . I am not positive on the size anymore but Matt can respond with the size. This happened relatively quickly after getting the boat new. Several things may have caused the looseness . When you or whoever puts in the new , these are stainless and require many more times pulling force than a single hand squeeze rivet tool. A two handled or air powered rivet tool is required. Otherwise they won't be tight. The other problem was cleaning and storage. I now store them knuckle up to assure the water drains out. Also I do not spray them with anything but clean water. I had used a protector which I think just lubed up the looseness and made it worse. Finally I know how to pack better and have the better rudder. I may have damaged these when I broke off the old style rudder in the everglades adventure. I started flooding due to submerging the stern trying to paddle steer into a 3 foot sea. The akas took a terrible amount of pounding in that 10 miles of fun. Oh how I love the new rudder. I check for looseness after every trip (many) and things are still tight


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PostPosted: Sun May 13, 2012 8:33 pm 
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I was thinking of epoxying nuts on the inside, so I can bolt (and re-tighten) from the outside. Pop-Rivets are so 80's! Any thoughts?

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PostPosted: Mon May 14, 2012 6:11 am 
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This thread is talking about exactly the same issues as

viewtopic.php?f=71&t=42549
MOVED FROM AI TO TI--AKA PLAY SEEMS EXCESSIVE

which I started, and continue to post on. This thread also confirms the concerns Nohuhu and I expressed there about how these loose joints would wear (or not) over time. Owners are definitely experiencing deterioration over one or two seasons that risk the boat in rougher conditions.

Also, as I explained in the other thread, excessive motion in these joints creates kinetic or shock loads on the mast plate--which is a issue unless you have the newer weld. Broken welds are discussed here

viewtopic.php?f=75&t=33638
TI FWD XBAR FAILURE

Personally, if nothing else comes of these discussions, I will probably epoxy the aka tubes into the pin assembly that inserts into the xbar. Larger screws or rivets will only solve the problem for a while. Larger holes wear and get larger as well. However, in doing the glue-up, I would still insert stainless screws to preserve the orientation of the aka in the assembly socket. Get that wrong, and the outer ends wont' insert into the ama's.

Personally, with around $8000 in this boat, trailer, and accessories, I need it to perform well, be safe, and hold its resale value. I expect all these issues will get worked out, but I don't think the loose joints can be ignored.

The requirement for strength in structures goes up generally as the cube (third power) of increases in size. So, since the TI is larger than the AI, these joints should, if anything, be stronger and tighter--certainly not looser.

I know it's all compromises, and it is wonderful to be able to disassemble so neatly and quickly. On the other hand, those of us who use the boats in rougher conditions may need to toughen up certain aspects. And the already loose joints should not get worse over a couple of seasons.

The harder question here is how to fix things, short of a serious redesign. Epoxying the pin assembly inserts into the xbar is not so attractive. However, since the vertical pin that the aka's swing in and out on is fairly tight, these two glue jobs would solve most of the problem. But then I might have to someday sell a boat with aka's that could not be removed, and deal during my ownership with not having the main hull ever free of these four tubes folded in along the sides.

I still think it's a great boat with a ton of wonderful design features put out by a wonderful company that cares about its products and its owners.


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PostPosted: Mon May 14, 2012 6:39 am 
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The Harken Cleat is not attached to the Xbar assembly using a pop rivet. The aluminum was drilled and tapped (8NC32?) and a SS screw holds on the cleat. Think of all the stresses of the sheet line on the cleat.

On the newer rear aka arms there is a clip that holds the brace onto the aka when you fold in the brace. It is called the "aka brace clip" and is installed at the factory with a rivet. However, if an owner of an older aka arm wants to add the missing clip Hobie has the "Aka Brace Clip Kit" part #79537001. No pop rivet - Hobie sends you the clip and a SS self tapping screw. You just drill the hole the right size and in the right place.

My 2 examples are to get Hobie thinking along lines of fixing the rivets with some type of screw and making them available to owners/dealers as a repair kit. Heck just tell me what screws should work and I'll run down to Ace Hardware.

Replacing old rivets with new rivets seems counter-intuitive if rivets have been shown to fail.

The real kick in the head was my 7 day Gulf sailing vacation where I saw loose rivets on the 2nd day and then had to worry about loosing an aka in heavy chop the rest of the trip.

Have another sailing vacation soon, hence my intense focus on this issue.


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PostPosted: Mon May 14, 2012 7:29 am 
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Several rivets on my TI akas knuckles have failed and completely fallen out. I appreciate the community's efforts to address this important issue.

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PostPosted: Mon May 14, 2012 8:45 am 
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Again, this conversation is developing on two threads (see above), so I'm posting this here as well as there. What I said there was:

Think about it. These joints have to do two things. One, stop the aka/ama assemblies from moving up and down relative to the long axis of the boat. That is keep the floats rigidly extended. The other is more subtle, but probably the source of much of the wear and tear problems. Drag on the ama's wants to move them backwards and thus ROTATE the aka pipe in its socket. So this puts sheer stress on the rivets (or any screws). Looseness creates a ton of repeated impacts on the rivets--perfect for deforming them.

The same thing goes on with the aka assembly insert where it fits into the xbar. It not only has to stop up and down motion, but it has to resist rotation. Rotation wants to happen to it not only when sailing, but what we fold the ama/aka assemblies in. The whole thing wants to sag down, because the inserts into the xbar are held only by spring clips. This brings us to the problem talked about in
another thread (can't find it now), where the inserts become very hard to remove, because they have twisted and now remain somewhat twisted.

An abstract design direction (with issues to solve) to correct all this would be go to to square cross section tubing for the xbar and the aka's. A square socketed within a square resists rotation because of its shape. This all comes back to me now because I built a small trimaran years ago where the aka's inserted into rectangular cross section sockets in the main hull. I tapered the ends of the aka's where they inserted, and then built the sockets using these as a form--so the fit, when the aka's wedged in tightly, was near perfect. Only thing needed then was a piece of line to hold the aka's from sliding out.

And I notice people are putting that same piece of line on now anyway to prevent accidental dismountings (that's another thread I can't find right now).

But we still need some sort of work-around or fix here it would seem, because square cross sections would be a whole redesign, and at that approach would cost in other ways if taken on the TI. And we would not see anything like that for a while, anyway.


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PostPosted: Mon May 14, 2012 9:17 am 
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Yes. I'm kinda sorry about the split threads on similar topics. Aka play from multiple sources is what is happening. Perhaps too much for Hobie to solve in one easy fix.

Loose, pulled out and missing rivets is however very specific and in my estimate an easy enough fix even if it only address part of the problem and is only short term.

I thought one purpose of the V2 aka was to introduce a replicable part (the knuckle) when the pin and connector wore out. Unlike the V1 akas which were all metal to metal and any excess wear in the hinge pin/connector would require replacing all the metal (akas & xbrace assemblies).

Once the knuckle wore out one would un-rivet the old/worn knuckle and rivet or bolt on a new one; reusing all your aluminum aka arms and braces. Having gone though 2 sets of worn V1 akas since 2006 the V2s showed real promise with the ability to replace just the worn end. Of course maybe I'm wrong about the intent of the V2 knuckle. :)

BTW I would rather buy a set of 4 knuckles every couple of years than a complete set of aka braces and arms. Assuming the former is much cheaper than the latter. Of course I may be an atypical user - putting a great deal of use on our AIs. 8)


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PostPosted: Mon May 14, 2012 10:07 am 
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These are all good points, Yakaholic. Thanks for making them.

It's true, if I were to epoxy the aka inserts into the xbar, then, when the vertical pins wear, it would mean replacing the xbar along with new aka assemblies.


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PostPosted: Mon May 14, 2012 1:07 pm 
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Everyone may want to review cliffs2yak's repairs for this rivet issue, posted last year.

http://www.hobiecat.com/forums/viewtopic.php?f=75&t=35292&start=0


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PostPosted: Mon May 14, 2012 1:57 pm 
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Ah, thanks Nohuhu. So that thread started a year ago and went on for about 6 weeks it seems. Lots there to think about. But also, if the problem has been around that long, I guess our company doesn't have much more to say about it yet.

My switch from the AI to TI came late last season, and the boat is used so far only in fresh water. So I have been anticipating and looking to prevent what I now know is pretty common negative experience. Yuck.

I worked with 3M 5200 (mentioned in Cliffs2yak's thread) extensively previously in my life when did wood and fiberglass work on small and larger boats. It was your friend when you needed incredible adhesion that would still flex a bit. It filled space and was awesome for quick, sometimes short-cutted repairs. But it was your enemy on a repair job if someone else had used it--because it was extremely hard to disassemble any parts thus joined.

I guess it would probably serve as well as epoxy in repairing or doing a preventive glue-based reinforcement. I would not just put beads in a couple of places, however. I don't think you would get the aka tubes out again anyway, so I would smear everything, and use that to slow down electrolysis. Epoxy, 5200--about the same effects I guess. Both are largely totally waterproof.

I feel like I'm looking at replacing the xbar with one with the new weld (I guess I just missed that production upgrade) and doing some serious retro-fixing on a brand new boat. Not what a new owner likes to see....


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PostPosted: Mon May 14, 2012 2:12 pm 
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C2Y had that degree of salt water corrosion after only 1 year I believe. That's something else to consider in this whole, loose joints/roaming rivets discussion.

It's another source of unseen Aka corrosion, and probably an additional risk to the health of the joint/rivets.

Will the 5200 stop the creeping corrosion? At the 1 year repair mark, maybe Cliffs can answer this.

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