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 Post subject: Cleated Ama Safety Lines
PostPosted: Thu May 14, 2015 6:23 pm 
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Since I'll dock during launch, retrieval and during almost all outings, I rigged cleated ama safety lines on a 2015 TI using 3/16" nylon. I moved the furling cleat closer to the mast receiver and added port and starboard cleats just inboard of the crossbar mounts using all pre-drilled holes and Hobie parts.

The lines run from the cleat forward wrapping around the crossbar then aft to loop around the aka where it enters the ama. Lines appear to run free of other running rigging.

I'm interested to hear any comments.

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PostPosted: Thu May 14, 2015 6:49 pm 
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I don't know how strong your cam cleats are with that nylon line. Assuming the cleat will hold in the event "collision" with an object (post, another boat, wave), you have a rigid system--the same as putting a steel shear pin in the aka brace. To put it another way, you could put a SS pin in the aka brace (a rigid system) & still be able to fold the aka/amas in when you dock.

In order for "ama safety lines" to work, their must be some give so that the nylon shear pin breaks. Fusioneng refers to his lines as "stretchy," and they ultimately break. If your lines do not stretch & they do not break, you have a rigid system. My Keep-Out lines (http://www.hobiecat.com/forums/viewtopic.php?f=70&t=7276&p=256156#p256156 Scroll down to near the bottom of that page) permit the shear pin to break, they stretch, but they do not allow the aka/amas to fold in--at least that is the plan. My lines do not allow for folding in for docking--your plan. Some combination of your cleating system and my stretchy Keep-Out lines might be your solution.

Keith

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PostPosted: Thu May 14, 2015 8:24 pm 
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I think most of the line tension will occur at the crossbar so I expect the cleat will hold. The line I used definitely has some stretch to it. Also, I don't plan to tension it fully so that the bolt will shear first and hopefully absorb most of the energy.


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PostPosted: Thu May 14, 2015 9:37 pm 
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Scc:
I like it a lot, it looks to be the perfect setup for someone who needs to retract/fold their AMA's often, simple ( I like simple), easy to implement. That size nylon rope typically has a working load limit around 90 lbs where it is strong enough if you do shear an AKA bolt while on the water (still highly unlikely), it will hold the AMA out long enough to get the sail furled and replace the shear pin without capsizing (the whole point of the safety rope), of course the nylon shear bolts will still shear, but at least you won't get a wet suprise like Keith did. The rope could also easily be tied to the fabric lift handle on the AMA, which if in the center of the AMA may give slightly better protection against the AKA bars slipping out, but I have a feeling where you have the rope tied (on the rear AKA), will also work fine (best thing to do is try it, just unclick the AKA latch buttons tug on it and see what happens (that's what I do I test everything)). The important part of the design is to not have a rigid joint in the center of the AKA bar (like from a stainless bolt), this would cause extreme (amplified by leverage) stress on the AKA bar itself possibly causing the AKA metal to elbow (bend/fold), take the ball off the hull, or worse yet rip the ball from the hull.
In the event of a real collision, it best to just let the brace break and fall away, then allow the AKA bars to simply fold in on their hinges (no damage should occur). In a collision that 90 lbs line is not going to stop anything, it will just stretch (obsorbing much energy), then eventually break if neccessary, but in reality if you hit something it's likely in a dock area near other boats, if you tip over and get scared 'just stand up', tip the boat back up, collect all the junk that fell out, and pretend it never happened cuz your likely right next to shore anyway if there are boats and docks near enough to run into ( lol), nothin to hit out in open water.
Like I keep saying it doesn't matter how you do it, as long as you test it yourself and understand the purpose.
Bob


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PostPosted: Fri May 15, 2015 4:43 am 
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scc & Bob, I question how "stretchy" that nylon line is. I attempted to stretch my 70# working-strength nylon line (it was shorter, about 5') and had no stretch. Your longer line may have a bit more "stretch." scc you can test it in your driveway by releasing the aka brace and pulling back on the aka/ama. A picture would be great.

Keith

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PostPosted: Fri May 15, 2015 8:43 am 
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I like this approach as I also launch and retrieve with the amas folded in.

How about rather than attaching directly to the rear arm, adding a small bungee loop to the arm and attaching the line to the bungee loop? Should provide the desired "give".

Gary

2014 Hobie TI (Cheesehead yellow)
1984 Hobie Hawk RC Glider


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PostPosted: Fri May 15, 2015 8:56 am 
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Chekika wrote:
scc you can test it in your driveway by releasing the aka brace and pulling back on the aka/ama. A picture would be great.

Keith


Good idea. I'll try to post something this weekend.


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PostPosted: Fri May 15, 2015 10:24 am 
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GaryInWI wrote:
I like this approach as I also launch and retrieve with the amas folded in.

How about rather than attaching directly to the rear arm, adding a small bungee loop to the arm and attaching the line to the bungee loop? Should provide the desired "give".

Gary

2014 Hobie TI (Cheesehead yellow)
1984 Hobie Hawk RC Glider


That would work too. Choose your level of desired stretch. I primarily wanted to share a solution for those of us that need to deploy and retract the amas frequently.

Another rigging option is to run from the cleats forward to the bow padeye (or a couple blocks attached to the padeye) then aft and out to the ama or aka (depending on your attachment preference).


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PostPosted: Fri May 15, 2015 8:26 pm 
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One question I have - is there any risk of the ama folding forward? If a sheer bolt breaks, might it be from rearward force (unlikely but possible)?

I really like that setup using a jam cleat for adjustable tension.


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PostPosted: Sat May 16, 2015 12:52 am 
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Totch wrote:
One question I have - is there any risk of the ama folding forward? If a sheer bolt breaks, might it be from rearward force (unlikely but possible)?

I really like that setup using a jam cleat for adjustable tension.
It can happen, but it's usually the windward Ama and it's less of a concern. Unless you are in breaking waves or sailing downwind.

Or, of course, you could be clipped from behind by someone in a RED AI. :mrgreen:


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PostPosted: Sat May 16, 2015 3:06 am 
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SCC do you happen to have the part number(s) and a good vendor for those Harken cleats handy ?

That looks like an excellent setup.

Thanks

Chris


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PostPosted: Sat May 16, 2015 8:00 am 
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Buckaroo wrote:
SCC do you happen to have the part number(s) and a good vendor for those Harken cleats handy ?

That looks like an excellent setup.

Thanks

Chris


Thanks Chris!

The Harken parts are:

Micro Carbo-Cam® P/N 471
In stock online.
$22.97

Micro Flairlead, Black, Fits cam: 468, 471
P/N 474B
In stock online.
$5.32

I bought them at a West Marine store http://www.westmarine.com/buy/harken--micro-cam-cleats-accessories--P002_064_002_502. I couldn't find better prices.

Black was the only option for the fairleads. If I ordered online, I may have picked a different color. :D

You will also need Hobie parts:

79531111 Mainsheet Cleat Wedge
8031481 8-32 x 1-1/4" SS Screws (2 per cleat)

My excellent Hobie dealer, Cal Canoe & Kayak - Oakland, supplied these.

You could also use 79531101 which is the cleat wedge with integrated fairlead used for the furling cleat. It has a symmetric base whereas the mainsheet wedge is asymmetric (it is slightly flatter on one short side). While it would be apparent that the furling wedge has a preferred orientation with the fairlead forward, the mainsheet wedge also has a preferred orientation with the flatter short side to port. If reversed, the cleat will not sit evenly on the wedge.

I didn't choose the furling wedge because the lines already run fair to the cleats.

Note that the Harken cleat risers are not the same as the Hobie cleat wedges. The Harken risers are flat on both sides whereas the Hobie wedges are concave on the bottom to mate with the curved crossbar.

Also, I used blue Loctite.

Good luck!


Last edited by scc on Sat May 16, 2015 11:35 am, edited 1 time in total.

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PostPosted: Sat May 16, 2015 9:12 am 
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I used the standard harken cleats with the flat bottom. I just doped silicone on the bar and put the cleat on then wiped away the excess, once dry the silicone holds everything rigid


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PostPosted: Sat May 16, 2015 10:05 am 
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FYI the wedges are $3 each.


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PostPosted: Sat May 16, 2015 2:03 pm 
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Thank You

Chris


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