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PostPosted: Tue Oct 18, 2011 2:59 am 
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Location: Kailua 96734
Aloha y'all

I've been meaning to share the story of some disturbing cracks I found on my original Hobie AI hull and how that lead to my recent conversion to the 2011 fuselage.

I also wanted to point out a source of potential structural failures for older hulls that are worth keeping an eye out for.

Finally, this story (like so many others), underscores why the Hobie Ownership Experience, while frustrating at times, is the best in the business.

==========================

Around the beginning of 2011, I was tinkering with my late 2007 AI, replacing worn parts, upgrading others and giving it a good physical.

After reading the great threads about Aka corrosion and sacrificial anodes (thanks Keith) I decided to pop off the Aka crossbraces and check under the mounts. This involves using a hex wrench to remove the stainless steel soc screws that fasten into brass receivers. It's not hard to do.

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I had noticed the slight weeping of white aluminum oxide from those spots since I acquired the boat from it's original owner. But I was not prepared for what I found,

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From above, my bars and hull had the appearance of being healthy, but an unseen cancer was eroding the aluminum bars from the bottom up. Essentially, you have stainless steel - on aluminum - on brass in a constant contact with salt water, setting up the eventual failure of the aluminum parts.

Image

The brass inserts and steel soc screws were still in perfect shape, but the aluminum areas around the soc screws were eaten way - and near the point of failure. After cleaning the corrosion from the bars, you can see that the holes were large enough for the screws to escape, meaning the crossbar could have ripped free under stress at any time.

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Worse yet, compression forces and plastic fatigue under the port mounts had caused fractures of the hull that could have caused serious issues far from shore.

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These fissures were still invisible, (unless you removed the crossbars), but were about to break out and spread downward, as you can see.

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So I had been happy as a clam, sailing hard every week until I found this problem. Once it was exposed, I judged it to be too dangerous for offshore use. I grounded the boat (in the middle of whale season) and contacted Hobie through my dealer. The whole process, with shipping, took about 3 months to resolve and I was high and dry during that time. (Try quitting cold turkey!)

They offered me a couple options, (and this is where it gets interesting).

- A reduced cost 2010 demo hull that was on island (wrong color)
- A 2011 RED hull at reduced cost (mmmnn,..new rudder??) But I would have to wait months for it to ship in.
- A 2011 RED hull at reduced cost + I pay the shipping to expedite. (That's what I decided on).


However, there were several problems with this:

- 2007 masts do not fit 2010 and 2011 mast receivers.
- 2011 crossbars do not fit the pinned 2007-2010 Akas.
- Older V1 drives become loose in the new hulls, etc, etc.


So Matt and Brendan built me a true "Hybrid" AI. It features:

- 2011 hull with larger T&S rudder and tiller,
- 2007 vintage mast cup and V-brace for my "male" mast.
- Pinned Crossbars for my original 2007 Aka/Amas. (one anodized, one not!)
- New axle for my V1 drive.


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If you saw it at the beach you might scratch your head awhile figuring it out. It's a real "Poi Dog", as we say over here, but I love the result. (New hull, handles, rudder and steering improvements along with the reliability of the ancient pinned Aka connections. No popping knuckles or loose rivets, etc to stress over).

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Hobie eventually replaced the rudder for me as well with the new one - my main reason for going with the 2011 in the first place.

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I'm still trying to figure out why the cracks and corrosion were worse on the port side. Probably sun damage from the original owner, maybe it was related to the few months I laid the hull on its side while storing it in the shade. Or maybe it had to do with the corrosion itself, building up localized pressure under the plates/screws and causing the plastic to lift and erupt. The pictures above show a clear bulging of the plastic under each contact point. The starboard side had hairline cracks starting as well.

I would highly recommend that owners of pre 2011 AI's pop their Akas once a year and inspect under the crossbars. It's unlikely that you'll find advanced material cancer under there, like me, but it's worth getting a checkup.

Thanks again Hobie - It's great to be back in the saddle.

Image

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Last edited by NOHUHU on Thu Oct 20, 2011 10:10 pm, edited 1 time in total.

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PostPosted: Tue Oct 18, 2011 4:58 am 
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Wow!!!! In both a good and bad way.

I have assumed that your boat just had a conversion kit on a newer hull since Hobie is still selling the pin conversion kits.

Great that Hobie was able to work with you to get a new hull and custom rig it.
Really sad that this happened, in the past, but you prove an important point about not just trusting but checking your equipment.

So in prevention, did you mount an anode on your improved hybrid?

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PostPosted: Tue Oct 18, 2011 10:52 am 
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Location: Kailua 96734
Naw. You caught me. Been too busy working on benches and batboats. ;-)

But could the zinc anode actually save the aluminum at the dissimilar metal contact points, or would it just slow the overall corrosion and peeling paint problem on the bars? I would think plastic washers would help more.

But I'm happy to revisit that debate and learn from them that knows.

The pictures of my AI clearly depict what CAN happen, in the extreme, if nothing is done.

And over time, I think my "hybrid" boat should settle the debate over which lasts longer, the anodized bars or the electroplated. :-)

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PostPosted: Tue Oct 18, 2011 1:45 pm 
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thanks for posting this - I know what I'll be checking this weekend as I've had a popping issue for a while now and checked all the suspect places except here

... hoping I dont find what you did :o

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PostPosted: Wed Oct 19, 2011 6:23 am 
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Location: Cape Coral, FL
There are two of types of corrosion that can be occurring here.

One is likely crevice corrosion under the akas. This will happen in any confined space, such as between the akas and the boat. It will also occur under paint, even electroplated paint, as soon as there is the slightest scratch. Opening space between the akas and the boat and flushing with fresh water will reduce this but not eliminate it.

The other is galvanic corrosion as has already been surmised. Nylon or rubber washers the best solution to this issue. The threads of the bolts also need to be coated with threadblock of some kind. Check your local marine supply store for it, I frequently get free samples at boat shows. Zinc or other sacrificial metal won't be very effective in this situation. For zinc to be effective, the boat must be bonded (everything that is being protected must wired together) and the zinc must be in constant contact with water. The only place I can think of is at the tip of the akas inside the amas. I would have to take mine apart to see how practical it would be to do so.

Goodluck,

j

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PostPosted: Wed Oct 19, 2011 9:08 am 
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Great 1st post j. Mahalo.

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PostPosted: Thu Oct 20, 2011 10:30 pm 
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Under similar circumstances ended up with a 2011 new hull. Fortunately my mast had the new base.

The hull came with new crosspieces so purhased new yaku.

But what has been done to new crosspieces on 2011 hulls to prevent similar corrosion?

Matt?

Aloha

Dan

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PostPosted: Thu Oct 20, 2011 10:55 pm 
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I thought about that too, but would have needed to purchase all new Akas, and a new mast at great expense overall for stuff I already owned.

This solution is working out well and is as uniquely individual as I am. :mrgreen:

I think the new 2011 crosstubes avoid alot of the dissimilar metal contacts. The aluminum bars are held on by a composite clamp. Yes?

Image

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PostPosted: Mon Oct 24, 2011 6:59 am 
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I'm reading this as i am waiting for a replacement hull for a similar crack-- actually not under the aka mounting points, but along that little molded ridge of the hull.
I pulled the aka cross bar, and low and behold-- corrosion...not quite as bad as yours, but enough that i'm up to the dealer this AM to order front and back replacements.


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PostPosted: Mon Oct 24, 2011 9:12 am 
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I guess you could consider buying a full 2011 Aka set as well, if your mast is compatible and your old bars are corroding.

In the picture above you can see that all of the mounting holes except one were experiencing advanced corrosion. Oddly, it was the hole at the leading port edge that looked fairly normal. Probably the wettest area in question too.

Some corrosion is normal but this was bad. Welding a new bottom plate to the bar and using larger washers is an option if you have the skills and want to repair the original crossbars. Mine were too far gone for hard sailing, I think. Despite washing regularly and spraying with wd40.

Good luck with the upgrade! You'll enjoy the new rudder.

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PostPosted: Mon Apr 30, 2012 1:01 am 
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UPDATE -My old Akas were in pretty bad need of a refinish, 3 years after the last touch up coat.

This time I wanted to use an aluminum primer, so I'm taking them down to the bare metal. Even with 3 different sanders, it's a big job. Heat guns were useless.

I spent at least an hour apiece sanding them this weekend. Still some detail work to be done. There was considerable corrosion on the bottom sides, and other areas I will show you later.

Has anyone used a chemical stripper, that worked for the Akas paint?

Has anyone used zinc chromate or the new self-etching primers as a base?

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PostPosted: Mon Apr 30, 2012 4:22 pm 
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We used to use Easy Off Oven cleaner for removing anodization on bicycle handlebars. No idea what that would do to the Aka coating.

BTW- thanks to this thread I'm ordering new aka cross bars V1 to fit my "Poi Dog"
2012 hull
male mast
2007 aka/amas

all in Red

NoHuhu we're twins!


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PostPosted: Mon Apr 30, 2012 4:59 pm 
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Got Hakas :?: :wink:

Sounds like you may need an Aka repaint too.

BTW, I received one anodized bar and one e-plated bar. Now I'm torn deciding if I should paint the Akas flat or glossy,...

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PostPosted: Mon Apr 30, 2012 6:55 pm 
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Here's a little before and after view:

Image

I've been analyzing the corrosion patterns, and one thing I can say for sure:
DO NOT PUT TAPE ON YOUR AKAS.

As you can see, the areas bearing tape have greatly accelerated corrosion. Even those areas where tape was added only a few months ago. ( All parts were sprayed/soaped/rinsed and dried prior to storage).

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Last edited by NOHUHU on Mon Apr 30, 2012 7:42 pm, edited 1 time in total.

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PostPosted: Mon Apr 30, 2012 7:18 pm 
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Here's a little before and after view:

I must need new glasses! :)

3 years after the last touch up coat.

Boy, time flies! 8)

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http://KayakingBob.com - - - - - Hobie Island Sailing since 2006 - - - - - 2011 & 2012 Hobie AIs and a 2012 TI


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