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 Post subject: Re: AI Crossbar Problem?
PostPosted: Thu Jun 21, 2012 5:58 pm 
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Not much will change insofar as the mast and sail are concerned. Everything is still level and the mast is in the same position as it would be if the starboard mounting clamp was even with the one on port.


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 Post subject: Re: AI Crossbar Problem?
PostPosted: Thu Jun 21, 2012 6:07 pm 
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But is it centered over the mast cup?


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 Post subject: Re: AI Crossbar Problem?
PostPosted: Thu Jun 21, 2012 6:30 pm 
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Definitely worth checking, but at the same time, the bars could be rotated 180 degrees and still be centered over the mast cup.

The most likely issues would be misaligned steering, increased drag = a "helm" effect, and poorly distributed loads on the mast cup, retainer and hull. Aka/ Ama geometry could be off, tramps not fitting, etc.

Sailing in circles,.. :lol:


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 Post subject: Re: AI Crossbar Problem?
PostPosted: Thu Jun 21, 2012 6:58 pm 
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That was my main concern - toe-in on the port side, toe-out on the starboard side. But again, we're talking a little bit.


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 Post subject: Re: AI Crossbar Problem?
PostPosted: Thu Jun 21, 2012 11:19 pm 
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If the fore and aft difference is only 5/16th, the side to side difference would be within the tolerances of the aka fit in the sockets and probably too small to even measure accurately. Those stickers really exaggerate that very small misalignment. I wouldn't worry about it at all.

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 Post subject: Re: AI Crossbar Problem?
PostPosted: Thu Jun 21, 2012 11:54 pm 
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I believe he said 5/16" at the crossbar ends, as opposed to 4 ft past that on each side at the aka ends/Amas. The effect out there would be amplified.

I know we are all just speculating. It kinda depends on what the other joints are doing too. A brace ball in the wrong position might even correct the toe in on one side. We don't know any of that for sure.

Best way to measure wonka-wonka would be fully assembled and with a protractor. I quickread several degrees clockwise rotation from the picture.

Tom - Is the rear brace square? Are the braced rear Akas square?


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 Post subject: Re: AI Crossbar Problem?
PostPosted: Fri Jun 22, 2012 5:00 am 
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Again, I'm not going by the stickers. I haven't even looked at them. The measurement difference is at the mounting points of the center cross bar. The rear bar mounting point is off by roughly the same distance. That's why I originally wondered if this was designed in for some reason.


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 Post subject: Re: AI Crossbar Problem?
PostPosted: Fri Jun 22, 2012 7:11 am 
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NOHUHU, as the akas are hinged, there is no reason for the error to be magnified out at the amas

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 Post subject: Re: AI Crossbar Problem?
PostPosted: Fri Jun 22, 2012 8:08 am 
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That is determined by the positioning of the hull pegs that the angled crossbars fit onto. On my hull, those are also off by 5/16+ of an inch to each other. So my Amas are parallel to each other, but they are not parallel to the hull.

I could remount the starboard side peg 5/16th inch forward, and that would bring the Amas and hull into parallel. While not great from an aesthetic point (stuff that touches the water would be in alignment, topside the stuff would still be off-kilter), it would be functional.


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 Post subject: Re: AI Crossbar Problem?
PostPosted: Fri Jun 22, 2012 10:16 am 
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Just as a reference Tom, the AI ama are always toed out. So as you have measured, it's just the difference between them, not the lack of parallel to the hull that might be a problem.

I still think the mast may be more of a problem than the aka/ama, if the top hole is further back and slightly to one side. Since the mast hole on the aka is not centered between the mount points but much forward. (NOHUHU, if rotated 180 degrees that would put the hole and rollers over the end of the Mirage Drive! :shock: :o :) ). Maybe a slightly raked back mast & sail could be good?

At 1/3" back at the aka would be over 1' back at the top of the mast.

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 Post subject: Re: AI Crossbar Problem?
PostPosted: Fri Jun 22, 2012 11:55 am 
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Tom, some toe in/ toe out is common, and worse on the TIs, but its not a big deal when it's balanced on both sides. Having only one side toe, or two with opposite toes is an issue.

The geometry may seem minor but think of it in terms if drag. Stick your palm in the water as you sail and you'll start to turn the boat. The further out you reach and the faster you go, the more drag you will introduce. This should reduce your speed and turn you sharper.

Aesthetics aside, that's one thing Tom will want to look out for. It might not be perceivable to him, until compared with another AI.

The other, as Bob noted would be if the mast retainer ring misaligns w the mast cup. We've all seen what happens to TI crossbars and masts when the crossbars are allowed to slip side to side less than 5/16".

No one's predicting a mast will fall on your head or you'll sail off the right side of the world Tom. I mean, we've only seen one partial photo. But at some point, wonka-wonka looseness or uneven drag on a plastic sailboat is undesireable.

It will be interesting to see/hear how things go on the water for you. Wish we could send some trade winds your way. ;-)


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 Post subject: Re: AI Crossbar Problem?
PostPosted: Fri Jun 22, 2012 12:06 pm 
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I'm well aware of the dynamics involved - it was once my business. That's why I posted this to begin with. It's not square, the Amas are not parallel with the hull. If they're all like this I'll live with it and just go sail. I just didn't know what tolerances Hobie tries to hold in a plastic boat. Maybe mine is within spec and maybe it's not. Still don't know.

If I got a bad hull, then I'll do something else.


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 Post subject: Re: AI Crossbar Problem?
PostPosted: Fri Jun 22, 2012 3:14 pm 
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Yes- It's very rare to see this particular defect. Otherwise, we wouldn't be that interested. :lol:


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 Post subject: Re: AI Crossbar Problem?
PostPosted: Fri Jun 22, 2012 3:16 pm 
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NOHUHU wrote:
Tom, some toe in/ toe out is common, and worse on the TIs, but its not a big deal when it's balanced on both sides. Having only one side toe, or two with opposite toes is an issue.

I can't see why it's so important that the toe in/out should be identical on both sides. The boat virtually never sails dead flat, unless you are in very light wind (or you are using a quarterdeck :roll: ), so the drag from the amas is always asymmetrical.
That said, any toe in/out will probably slow the boat slightly. You would think the amas would present the least resistance when they were pointing dead ahead.

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 Post subject: Re: AI Crossbar Problem?
PostPosted: Fri Jun 22, 2012 4:08 pm 
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That's my whole quandary - water and wind move. How precise does a sailing vessel have to be before you lose any practical speed or control? Sure, for $4K I'd like a boat that is square in every detail (Okay, not perfect, but closer than 5/16th to 3/8th inch). But if everybody's AI is off this much then I'll accept the fact that this is as close as they come and it won't make much difference.

Again, just wondering if anyone else has checked theirs.


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