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PostPosted: Sun May 06, 2012 7:48 am 
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Sold an H16 and my AI last summer, to consolidate to a 2011 TI. Got it, spent most of the rest of the East Coast season converting a Trailex so that it had four support positions for the TI. Sailed some, and got a little nervous

How much play (wiggling) is normal or good for these new insert-mounted aka fittings? I trusted the AI in waves and even some shorter, steeper chop--but I don't like what I see happening on the TI. The older AI pinned connections holding the akas to the main hull were very solid. Putting say barber hauler tension on the back of one float didn't shift anything. The akas were not bouncing up and down slightly within their sockets. This new arrangement on a larger structure seems counter-intuitive. With amas extended on the trailer, lifting up and down on each ama at the aka attachment point, I get 3-5 inches of movement. Some are tighter than others.

Is this a design choice? Is the fact that the ama can hobbyhorse somewhat separately from the main hull a virtue?? Normally larger structures have to be firmer, otherwise. I've read here about the accidental aka dismounts, but I'm wondering if there is some way to stabilize them, in addition to insuring that they cannot dismount.

Any wisdom accumulated about this?? Anybody else worried about it and tried to fix it? Or is it of no concern despite the loosey-goosey feeling? Thanks!


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PostPosted: Sun May 06, 2012 9:21 am 
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Many of us have added a second bungee to hold the ama better and stopthe galloping.

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PostPosted: Sun May 06, 2012 10:52 am 
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Mike, congrats on the new TI!

I have the older pinned Akas on a new AI hull, and know just what you mean.

It may just be our "frame of reference" but the TIs seem to me to have a scary amount of Aka flex and rotation (twist).

Those could contribute to the wobbling you sense, or they could also "smooth out" the ride on the water, like leaf springs on a car. It seems counterintuitive to me that so much play could be a good thing, but I hang out on the TI Akas a lot and have not met with disaster -yet. :wink:

I have noticed that some of the newest TIs seem looser than last years, so it's not just a symptom of age (like the loose rivets).

It's a paradox. Question is, do the knuckled AIs have the same degree of deflection? Any adverse effects there?

Loose joints may just be a matter of perspective for old stiff guys like me, but I share your interest and concern about it.

But as KBob says, the wobbling Amas are no illusion. Those bungees need to be reinforced!

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PostPosted: Sun May 06, 2012 1:51 pm 
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@Bob--"add a second bungee" where? Are you talking about the bungees that hold the akas into the ama sockets?? I just can't visualize what you mean. Thanks


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PostPosted: Sun May 06, 2012 2:09 pm 
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Looks like this:
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Here's a few old posts to read:
http://www.hobiecat.com/forums/viewtopic.php?f=69&t=40730
http://www.hobiecat.com/forums/viewtopic.php?f=75&t=30065&p=122645

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PostPosted: Sun May 06, 2012 2:15 pm 
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Just to be clear on exactly where the excessive play is.
Are you talking about loose ama at the end of the aka (which is fixed by the second bungee) or rotational movement of the aka/ama at the aka crossbar?
If the later then that is normal and is due to the new knuckle design.
If you're worried about excess pressure from a BH then you may want to try a whisker pole. I have a pole camera mount which doubles as a WP. Others use a notched double paddle.


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PostPosted: Sun May 06, 2012 4:31 pm 
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@Stringy--thanks for the clarification. I'm talking about rotation of the aka arm in the vertical direction about the long axis of the boat. If I place a 4 ft ruler upright next to the starboard ama where the forward aka inserts, then, at rest it is 3.5 inches lower than when I lift up the ama/aka at the same place. If I place the same ruler vertical at the bow of the starboard ama and lift up, the travel in the upwards direction is 5.5 inches (since the motion is magnified at the bow).

This rotation, when I look closely, is a combination of looseness in the fit between the inboard aka insert and its main-hull socket, along with some looseness in the fit between the vertical pin (on which the aka swings in and outboard) and its upper and lower collars.

If this much is normal, does that mean it's a design feature, or just that those are the tolerances of the manufacturing process, and they can't get any tighter.

This much ability to rock fore and aft independently from the main hull is not something I've seen in trimarans before. Or catamarans, for that matter. Usually, one of the ways you inspect a multihull is to shake or jump on the bow of one outer hull and see if there's any play between the hulls.

I'm new to this boat, so I don't know whether typical concerns apply to it. The AI did not do this. Thanks again for your help.


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PostPosted: Sun May 06, 2012 4:35 pm 
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OH ALSO--I always dismount the original ama bungees when I'm not using the boat. The minute it gets on the trailer, they come off. So it doesn't seem like they have stretched at all.


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PostPosted: Mon May 07, 2012 12:57 am 
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Mike- regardless if the Aka motion is a "feature" or not, adding Haka benches or tramps will make things feel much tighter and secure.

Aside from their many other benefits, of course.

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PostPosted: Mon May 07, 2012 4:39 am 
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Yeah Nohuhu... I'm starting to lean that way too.

I'm starting to think about adding that 3rd aka socket bar (don't know part name) in the stern and just extending out akas partway, and then angling a bench from it out to the normal rear akas. Haven't thought it out yet, but I used to build wooden boats--so that gives me a nice project to think about. Maybe it's impossible, but perhaps I could indulge my fetish for control of the sail shape by working a mainsheet traveler into this arrangement. Probably won't have time to build anything like this till later this summer, but I'm impressed by the Haka idea.

Still, anybody know anything about design tolerances for this whole loosey goosey aka-ama connection on the TI?


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PostPosted: Mon May 07, 2012 10:51 am 
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Oh, and I already have the tramps...


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PostPosted: Mon May 07, 2012 11:53 am 
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Quite a few have broken aka by hitting things, or beach landings with shore break, but I haven't heard of anyone breaking one while just using the tramps (or Haka). But, then again, you could be the first! :shock: :lol:

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PostPosted: Sun May 13, 2012 11:02 am 
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I've just read the thread on the TI FWD XBAR FAILURE. I suppose I probably have the old, questionable weld--since my TI is from mid summer last year. I sail a lot in buffeting, turbulent wind, and also often in shorter chop. I dream of and scheme ways to get clean air and long waves, but don't have them most of the time. Hence my concern about looseness in the aka/crossbar joints expressed here.

Out on Thursday, in those kinds of gusty winds and with a short beam sea running (so that the boat is parallel to the waves)--the TI does a little snap roll as the peaks and troughs roll under. 5.5 inches of play in each forward aka means that the each of the three hulls move up and down relative to one another a lot. The main hull, as well as the mast top (where all roll motions are exaggerated further) rotates back and forth relative to the aka's and ama's.

This looseness imposed not just stress, but also kinetic shock loads on the joints, especially if compounded by a strong puff hitting in phase with the leeward roll. If one of the things I'm supposed to do to make sure my mast plate is not going to separate from the crossbar is to make sure that there is no play in the tensioners and fastening bolts--well, that is the same kind of concern about shock loads versus static load.

The fact that the loose aka's allow the main hull and mast to build up momentum rotating independently from one another before the ama buoyancy kicks in to stabilize things does not help the weld situation on the crossbar.

Looking closely at the aka/crossbar joining hardware, it's clear that there are three sources of looseness. The vertical pin that allows for and aft rotation is pretty tight. But the male insert into the crossbar moves in its socket, and the aka tube moves where it is riveted into a female receiver on the pin assembly. So the second two are the main culprits.

One could epoxy the aka tube into the receiver, which is the same kind of thing racers do with H16's on some joints. One could also give up the ability to remove the aka's from the main hull, by epoxying these into the crossbar sockets. Not sure I want to do that.

I was willing to think well maybe this is a design choice, this looseness. But now if you compound this looseness with the kinetic shock loads being placed on, not just the aka/crossbar joints, but on the mast base assembly--I get a bit more nervous.

I could trust my AI in Barnegat bay bashing about in any conditions I would care to sail in. This TI doesn't seem to be that kind of boat, yet, anyway. All design is compromises--for sure. And we are on the leading edge (sometime also bleeding edge) of the TI design/production process.

If I look at one of the videos here claiming to show 20-30 knots, I see neither waves, nor whitecaps, and an ama which may be nearly buried, but also running utterly smoothly in flat water. How big was that fish? How strong is a wind with no whitecaps? In any case, it's not that kind of smooth sailing that concerns me. No rolling, no shock loads--not a problem.

I wonder one of you would at least compare the play in your TI with the figures from mine. At least I'd like to know if I should talk to my dealer about a production problem or not. Here are the figures again.

"I'm talking about rotation of the aka arm in the vertical direction about the long axis of the boat. If I extend the ama's with the boat fastened on its trailer, and place a 4 ft ruler upright next to the starboard ama where the forward aka inserts, then, at rest it is 3.5 inches lower than when I lift up the ama/aka at the same place. If I place the same ruler vertical at the bow of the starboard ama and lift up, the travel in the upwards direction is 5.5 inches (since the motion is magnified at the bow)." Thanks


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PostPosted: Sun May 13, 2012 4:07 pm 
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Mike

I share your concerns but don't have the time to elaborate right now.
So I'm just joining the thread and will add more when time permits. :wink:

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PostPosted: Sun May 13, 2012 7:01 pm 
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Perhaps some of our TI Haka bench users can comment here.

With the weight of the boards and the hiking passenger, it seems to remove a lot of the wonka-wonka.

On the benches, I get a very secure feeling while riding outboard (despite the flexing you can see in the knuckles).

But whenever I assemble or breakdown a stock TI, the amount of Aka wiggle room makes me uneasy (especially after I see the rivets start to walk).

Technically, shouldn't this be a potential problem for the new AI's too? I hear less chatter about this from AI owners, than from TI owners.


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