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PostPosted: Fri Feb 22, 2013 7:51 am 
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Location: Palm City, Florida
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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Sun E Sailor
Ezra Appel
Palm City, Florida
2014 Tandem Island


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PostPosted: Sun Feb 24, 2013 7:36 pm 
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Location: Cape Coral, FL
Sunny,

X2

I replaced the rivets on my ti with AL rivets and used lexal as a bonding agent. It's been a year and they are still solid and corrosion free.

J

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PostPosted: Mon Feb 25, 2013 3:58 am 
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Thanks sun E. I missed the original post and didn't realise that there was a Hobie fix for this. With mine the corrosion is starting to creep in so I reckon a fix will be a good winter project.

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PostPosted: Mon Feb 25, 2013 4:59 am 
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I did my front Akas several weeks ago getting ready for the EC. I measured the drop at the Ama. Two inches gained after the repair on each side. That can be a considerable difference over a long distance in reduced drag. So the theory goes. I needed to persuade my self into doing the job. Used epoxy and new stainless rivets even before this topic came up....

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PostPosted: Mon Feb 25, 2013 12:47 pm 
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Location: Palm City, Florida
Confucius said: "He who walks on two paths gets pain in crotch". :shock:

Sorry guys - I posted this article in two places; here and in the Open Forum - Islands section as well. So the following is my response to NOHUHU's questions from there.

sun E sailor wrote:
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 Feb 25, 2013 2:58 pm 
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Location: Sarasota,Key West FL
Hey guys:
I have a 2012 Tandem Island now (my 3d TI), and I noticed that the AKA knuckles on the newer boats are a different casting now. The little elves at Hobie factory have been at it again with another improved design (yes they listen to us). The diameter of the bore that the AKA bar fits into fits very nicely now ( I can't tell if it's glued in or not). Knowing what I know now, as soon as I brought the new boat home, I took the AKA arms and sprayed Krylon clear spray paint into the tube sockets (filling them up), I also soaked all the rivets with the clear spray paint. I then sprayed a thin layer of clear coat over all the AKA bars, and also any painted or anodized aluminum on the boat. I think it paid off because I have not noticed any corrosion on my new AKA's (knock on wood). Another trick that I do is wrap the entire AKA bars with black 3M electrical tape (like you would wrap bike handlebars). This keeps the AKA bars from getting banged up when you throw them in the back of the car. It's pretty easy to just replace the tape once in a while, but I haven't needed to yet. The good 3M electrical tape is a little more expensive, but well worth it, and it holds up in the sun if you use black only, they use carbon black to color the tape (carbon black completely blocks all UV).
Hope this helps
Bob


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PostPosted: Mon Feb 25, 2013 4:09 pm 
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I remember Matt saying they epoxy those rivets at the factory now.

Bob, regarding tape, I've found that ANY metal areas that are taped, (with any material, even non-adhesive rescue tape) will invite corrosion. Even if you are fanatical about cleaning the boat.

I used to wrap my akas for protection, mounting fishing gear and other reasons, and these spots trapped moisture and salt, causing corrosion rather than preventing it. Black tape in particular heats up, stretches, and traps moisture, probably adding to the problem.

When I ripped the bandaids off, there were strips of bubbled corrosion, mostly on the undersides, where the water rests. Keep an eye out for this.

I like your clear coat ideas though.


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PostPosted: Mon Feb 25, 2013 6:56 pm 
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NOHUHU:
I think the durability of the 3M tape is the key here (it has to be the black super 88+ 3M electrical tape) (" no other color or brand will work"). I've also used the super 33+ which also works ok, on other projects. They are both good to 221 degrees F.
I first mentioned this way back on this thread back in summer 2011
viewtopic.php?f=75&t=36070, and had already been using the tape for a year at that time on my AKA arms. I had noticed that my AKA bars were getting banged up from piling them in the back of my car every weekend, thats when I added the tape. My original thread The ultimate Tandem Island ( viewtopic.php?f=69&t=33720 ) on the first pic has the tape on the AKA's (I zoomed up on the original jpeg file to verify, see below) I can't explain why but it just works, I've never had any difficulties with corrosion under the tape. I have no idea why because I'll be the first to admit that I very seldom clean or even rinse off my AKA bars (actually never). Honestly I just throw them in the back of my car and they stay in there all year round. I take the boat off the car and put it in the garage, then I rinse and oil my motor and mirage drives and store them in the garage But things like the seats, paddles, life jackets, anchors, and the AKA bars just stay in the back of the car all year round because I'm out most every weekend anyway.
Hope this helps
Bob

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