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PostPosted: Wed May 16, 2012 4:29 pm 
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Yakaholic, Re the V2 Aka joints, I have only seen this partial diagram.

Image

There must be more complete CAD images at Hobie though.

It's difficult to visualize and comment on some of these issues without clear images.


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PostPosted: Wed May 16, 2012 6:12 pm 
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mmiller wrote:
Yes... we do learn things along the way. They are now glued.
Thanks Matt. That makes sense.
sun E sailor wrote:
Haven't we about talked this one out :shock:.
Gotta agree at this point. We now know:

- Hobie is gluing all new knuckle joints to the akas.
-They are supplying a glue and rivet kit to repair existing joints.
-They are not supplying the knuckle joints as a separate part from the akas.

As long as the glue holds, I guess there's nothing more to be said.

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PostPosted: Wed May 16, 2012 6:37 pm 
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chrisj wrote:
-They are not supplying the knuckle joints as a separate part from the akas.


Well, that is unfortunate. When the knuckle pin and bushing wear out you have to buy the complete ama and we all know you can remove and re-rivet the knuckle to the ama.

I'm optimistic that once Hobie gets ahead of it's parts inventory they will make this part available.

Or maybe they are working on an even better design.


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PostPosted: Wed May 16, 2012 7:05 pm 
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Well they must be using some pretty heavy duty glue to bond the knuckle to the aka (hopefully), so it may not be so easy to separate the two parts further up the road.

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PostPosted: Thu May 17, 2012 5:22 am 
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Thanks mat.
Well I have had a good look at my glued and riveted 2012 version aka knuckles today and am pleased to report they are holding up well, with no signs of looseness at all. So the new glue version seems to do the business.

By the way for further corrosion prevention (which I have seen quite a few comments about), I have used a product called Penetrol. http://www.floodaustralia.net/products/ ... i_rust.php
I used it in a spray can as it is easy to apply and has a thin tube nozzle to spray in bolt holes.

This stuff is brilliant as a corrosion proofing clear coat. When the boat was new and clean, I sprayed it on all the aka parts and let it soak into the gaps and joints and around bolts and rivets (it is thin and soaks in easily) I then wiped over all the exposed metal surfaces so it only had a thin smear coat to dry clear without looking like there is any coating at all other than a slight glossy look.

The stuff stops threads from coming unscrewed (like locktite) and stops salt water getting in and corroding threads in aluminium.

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PostPosted: Fri Feb 22, 2013 7:44 am 
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To review:
viewtopic.php?f=71&t=42667&start=15
LOOSE RIVETS ON AKA KNUCKLE ASSEMBLY
Unfortunately my pictures have been removed by Image Shack.

It's been almost a year since I replaced my original 3/16th's stainless steel rivets on my aka knuckle assembly, with 1/4" aluminium structural rivets. Here's the follow up.

I noticed the knuckle joints were starting to get loose again so I decided that this time, I would remove the rivets and assemble everything back together again using 3M 5200. I hadn't used it in May because at that time (May 14th) it was till being discussed as to which way was better. I also (thought) that the knuckle joint was a separate part from the aka itself, and that if I ever needed to replace it, it would be better not to glue these two parts together.

The following day (May 15th) Matt M. wrote:
mmiller wrote:
We created a kit for that.
81412001 AKA CASTING GLUE KIT - V2 AKAS
1 GLUE / 16 RIVETS (4 per AKA) $7.99 (USD / Spring 2012)
16 # 8010181 Rivet 3/16 x 1/4 grip length stainless
1 90 second cure epoxy
I had just done my repair the day before w/o any glue so I figured I'd have to see how it held up.

February 21, 2012.
Although the joints were loose this time, I found absolutely no corrosion or electrolysis inbetween the aka and knuckle joint, whereas last time (with the stainless steel rivets, there was quite a lot to clean up first).

Conclusion: Aluminum structural rivets are better in combination with epoxy or 3M-5200. Interestingly enough, after Matt's posting I replaced all the rivets on a friends TI using 5200 and his are still solid as a rock. I'm fairly confident now that this method is the right way to go. As a bonus, it comes in black now which blends in better too.

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PostPosted: Fri Feb 22, 2013 12:38 pm 
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sun E sailor wrote:
Conclusion: Aluminum structural rivets are better in combination with epoxy or 3M-5200. Interestingly enough, after Matt's posting I replaced all the rivets on a friends TI using 5200 and his are still solid as a rock. I'm fairly confident now that this method is the right way to go. As a bonus, it comes in black now which blends in better too.
Sun E, are you saying you used the Hobie SS rivet kit on your friends TI and they are holding great with 5200? And no corrosion?

You noted that your alum bits were loose again but clean of oxidation. Was there a big difference in the duty cycle or stresses for these 2 boats?

And we assume you mean Feb 21, 2013?


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PostPosted: Sun Feb 24, 2013 5:06 pm 
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sun E sailor wrote:
Conclusion: Aluminum structural rivets are better in combination with epoxy or 3M-5200. Interestingly enough, after Matt's posting I replaced all the rivets on a friends TI using 5200 and his are still solid as a rock. I'm fairly confident now that this method is the right way to go. As a bonus, it comes in black now which blends in better too.

NOHUHU wrote:
Sun E, are you saying you used the Hobie SS rivet kit on your friends TI and they are holding great with 5200? And no corrosion?

NOHUHU,
No - What I'm trying to say is that a year ago I took the original Stainless Steel 3/16" rivets out of my friends TI and replaced them with aluminium 1/4" structural rivets AND used 5200. To date his aka knuckle assembly is still solid as a rock.
NOHUHU wrote:
You noted that your alum bits were loose again but clean of oxidation. Was there a big difference in the duty cycle or stresses for these 2 boats?

No - Both Marc and I sail our boats quite alot and we're often together. The lack of oxidation due to electrolysis that I saw was inside my aka knuckle assembly that I took apart just the other day and have now repaired using 5200 and 1/4" aluminium rivets.
NOHUHU wrote:
And we assume you mean Feb 21, 2013 ?

Yes - February 21, 2013. Sorry about the confusion. That's what I get for trying to get this post written, while Laura and I were rushing out the door to go visit our friends for the weekend :roll: .

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PostPosted: Mon Mar 18, 2013 2:30 am 
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Hi Guys,

Just revisiting this thread, as my knuckle-joints are starting to show the dreaded sloppiness...

Could of questions, before I make the repair:

1: Should I use stainless of ally rivets? There seems to be a difference of opinion - the Hobie kit uses s/s, but other gurus seem to prefer aluminium.

2: Is the 3M 5200 epoxy the ultimate 'glue' to use? Is this what's in the Hobie kit? (haven't checked to see if this 3M stuff is available here in Oz yet...)

Cheers,

Mike.


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PostPosted: Mon Mar 18, 2013 4:13 am 
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mingle wrote:
Hi Guys,

Just revisiting this thread, as my knuckle-joints are starting to show the dreaded sloppiness...

Could of questions, before I make the repair:

1: Should I use stainless of ally rivets? There seems to be a difference of opinion - the Hobie kit uses s/s, but other gurus seem to prefer aluminium.

2: Is the 3M 5200 epoxy the ultimate 'glue' to use? Is this what's in the Hobie kit? (haven't checked to see if this 3M stuff is available here in Oz yet...)

Cheers,

Mike.


Mike,

We use aluminum to reduce the amount of galvanic corrosion, a serious problem for salt water boats. Aluminum is not quite as strong as stainless steel, which is why we used larger diameter rivets. Hobie recommends using epoxy for the knuckle joints. I used Lexel (clear) and others used 5200 (white), both are tried and both work. 3M 5200 should be available in every marine supply store, it's almost an industry standard. Lexel is the only product that sticks our plastic boats (and to EVERYTHING else, clean it quick or its there forever).

Cheer,

j

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also a more manageable 100 square foot spinny...
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PostPosted: Mon Mar 18, 2013 8:02 am 
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This may be hard for some to believe, but with a good epoxy and proper surface prep, the rivets are superfluous.


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PostPosted: Mon Mar 18, 2013 11:29 am 
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Tom Kirkman wrote:
This may be hard for some to believe, but with a good epoxy and proper surface prep, the rivets are superfluous.


I would agree with you Tom, but an epoxy bond that "works" or moves is the most likely bond to fail. If the bond is backed up with a mechicanical fastner, it is far less likely to fail and the holes are already there...

j

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also a more manageable 100 square foot spinny...
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the TI3 rear ama mod


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PostPosted: Mon Mar 18, 2013 11:42 am 
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The few parts I've had apart and re-glued did not have the rivets replaced. I don't fear a failure but that's coming from my association from some of the guys who did the early work on epoxies and adhesive techniques. Done properly, they don't fail and mechanical fasteners can actually weaken the structure. However, as you said, the holes are already there so you might as well. I'm sure having the rivets back in place allows many to sleep better.

Don't mind me, I just threw it out there. Carry on.


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PostPosted: Mon Mar 18, 2013 9:42 pm 
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what would keep me up at night would be that "proper surface prep". I recently glued (and re-riveted) my (2010 TI) akas, and did some surface prep, but not down to roughing up bare metal, as I probably should have, especially if I wanted to skip the rivets (which are hard to put in fully neatly, even with a two-handed riveter purchased especially for the project.) Also, I wish Hobie's kit had included a bit less instant-set epoxy. Hard to make it all neat in time. Nonetheless, I am pretty confident that I will not have problems with loose aka knuckles now.


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PostPosted: Mon May 13, 2013 8:19 pm 
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One other question I have (for those who've replaced the rivets with aluminium ones) is don't most (all?) ally pop-rivets have mild-steel pin/mandrel running down the centre?

Wouldn't this cause corrosions issues too?

Or should I be looking for marine-specific aluminium rivets?

Cheers,

Mike.


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