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 Post subject: Adding a Jib to the Ti
PostPosted: Fri Jan 17, 2014 8:59 am 
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Now I have mucked up the other threads by posting in the wrong places I thought it best to start a new one now I have embarked upon my build here in wet old England.
I am picking up the boat from the marina at the weekend and the jib with its spar will be here next week so I will post some more pictures as we progress, in between floods.

With the furler jib on the way from Aero Luff Spars thoughts turn to the topper.

I have concerns that a straight rod, front to back, may suffer bending if not strengthened as Bob has done with his top brace. So i am considering laser cutting this from stainless sheet and favor the top option.
I would think 5mm should do it without being too heavy. Ali would be better but you cant laser it.

I am looking at bearing options for the topper and am hoping to make a nice free bearing for it. we shall see.

whaddaya think?


CC

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PostPosted: Fri Jan 17, 2014 9:05 am 
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Next question:

I see everyone so far has taken the loads from the jib back to the AKA's. Does this need to be done or is it sufficient to strengthen the hatch opening as I have suggested previously? which is of course not as easy in reality as it is on the computer seeing as the boat is curvy!

The answer may well be suck it and see, but thoughts would be welcome

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PostPosted: Fri Jan 17, 2014 6:51 pm 
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I haven't had any issues with the square tube bending on my AI with my jib that is way too big. I think I would flip the boat before they bent.


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PostPosted: Fri Jan 17, 2014 8:16 pm 
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I like your approach using the tracks. But perhaps an exoskeleton in overkill?

I would think that a proper backing plate would handle a small jib. Or plates, if you want to add a short sprit.


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PostPosted: Sun Jan 19, 2014 12:43 pm 
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NOHUHU wrote:
I like your approach using the tracks. But perhaps an exoskeleton in overkill?

I would think that a proper backing plate would handle a small jib. Or plates, if you want to add a short sprit.


Yes you are right. i have just trailed the boat back and at first look the bow is straight enough to just add a tube to each side. I dont think it is essential that it connects to the AKA itself so I will press on with my yackattack demountable idea as soon as I can find some tube.

CC

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PostPosted: Sun Jan 19, 2014 1:22 pm 
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ALuminum cuts well on C02 lasers, I cut it all the time. Alternatively water jet will cut it.
www.peridotcorp.com


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PostPosted: Mon Jan 20, 2014 12:41 am 
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ppicker wrote:
ALuminum cuts well on C02 lasers, I cut it all the time. Alternatively water jet will cut it.
http://www.peridotcorp.com


Yes. I havnt access to one that will do it. What sort of cost would you charge for the topper at bthe head of the post in say 6mm Ali to the UK?
Cc

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PostPosted: Mon Jan 20, 2014 12:41 am 
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Chopcat wrote:
ppicker wrote:
ALuminum cuts well on C02 lasers, I cut it all the time. Alternatively water jet will cut it.
http://www.peridotcorp.com


Yes. I havnt access to one that will do it. What sort of cost would you charge for the topper at bthe head of the post in say 6mm Ali to the UK?

Overall lenght 900mm
Cc

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PostPosted: Mon Jan 20, 2014 2:06 am 
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Chopcat, I misunderstood you when you were talking about bending. I thought you meant the bow brace. My Mast topper uses 12mm Stainless Steel and does not need any bracing. Going off the strong winds I had one day when testing, I think my mast would snap before it bent.

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PostPosted: Mon Jan 20, 2014 7:08 am 
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Chopcat / john:
The only reason for the bow brace is to give you something else to connect to besides the bow pad eye, and help re-enforce the bow a little to prevent the front hatch from leaking like a siv from the up and down bending motion of the bow with a jib or spinnaker mounted. Myself and others only attached to the aka bar because it's the strongest point on the hull. I'm sure yak attack bars mounted just in front of the brace will work just as well. Extra cross bracing is probably overkill. Even with no jib at all the bow bends up and down and water leaks into the hatch as you go thru the waves, the brace pretty much stops the leaking.

On the mast topper lighter is better (weight aloft), my current mast topper is under two lbs. johns stainless topper will be plenty strong as is. I only bent mine by doing very stupid stuff like trying to fly 260 sq ft of sail in 25 mph winds ( not a good idea). My mild steel topper only bent because I was doing almost 20 mph, hit a gust and a big wave at the same time and the boat dove and stopped ( dumb thing to do). With johns topper if he is worried about it bending, a piece of spectra string strung from front to back and over the top in the center, would strengthen it more than enough for pretty much any thing ( I recomend using lightweight nylon (stretchy) rope for the rear stay line, it's only there to prevent the topper from spinning and to protect the mast holder in the bottom of the hull ( that 1/4 inch stud) from being over stressed on a downwind run in higher winds (mostly with spinnakers). Pretty much any design will work, again no reason to over design. If running just a jib that rear stay is less important ( unless it's frickken huge (lol)).
Also the TI and AI are different boats. The mast on the TI is mounted too far forward on the TI kind of making the bow sprit needed if you want to run both a jib and a spin, and might be unnecessary on an AI (because the mast is further back).
I would love to see video of these in action.
Good luck
Bob


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PostPosted: Mon Jan 20, 2014 7:52 pm 
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Hadn't really thought much about the twistoflex action on the front hatch seal. Good to consider this and have a 2nd inner seal to ease the slurping effect.

I've noticed that hulls vary quite a bit in thickness and rigidity from boat to boat. Some AIs could require more bracing than others. The AI bow takes more of a beating them the TI, due to its shorter Amas, but the TI experiences massive flex from the larger sail.

On either boat I would think that the jib cleats would be the weakest point. You should use good hardware and mount it well.

How are you planning to do this?


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PostPosted: Tue Jan 21, 2014 11:23 am 
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NOHUHU wrote:
Hadn't really thought much about the twistoflex action on the front hatch seal. Good to consider this and have a 2nd inner seal to ease the slurping effect.

I've noticed that hulls vary quite a bit in thickness and rigidity from boat to boat. Some AIs could require more bracing than others. The AI bow takes more of a beating them the TI, due to its shorter Amas, but the TI experiences massive flex from the larger sail.

On either boat I would think that the jib cleats would be the weakest point. You should use good hardware and mount it well.

How are you planning to do this?


I have upgraded my main to a spinlock swivel cleat and was proposing to use these with some backing plates mounted on the tops of the hull for the jib lines in the area where the cleats for the spray skirts are. The roller furler line will go to the left hand side of the mast with a cleat mounted on the AKA rail. (if that makes sense)

I agree the cross braces are overkill looking at the boat now so i will go with a tube either side and see !

CC

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PostPosted: Tue Jan 21, 2014 2:03 pm 
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I like those swivel cleats for the jib lines! The furling line should only require a micro cam.

Anyone considered placing their jib cleats just outside the knuckle joints on the Akas?


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PostPosted: Wed Jan 22, 2014 12:05 am 
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The problem is that with the swivel cleats you need a flat base to mount them on. I made one up for the main sheet using the plastic adapter that came with the original and an aluminium plate. So it could work.

Then there is the complication of the tramps, where i suppose you could cut a hole in them.

It mightbe a nicer position for them. I will think about it.

Cc

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PostPosted: Mon Jan 27, 2014 1:15 am 
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Chopcat wrote:
The problem is that with the swivel cleats you need a flat base to mount them on. I made one up for the main sheet using the plastic adapter that came with the original and an aluminium plate. So it could work.

Then there is the complication of the tramps, where i suppose you could cut a hole in them.

It mightbe a nicer position for them. I will think about it.

Cc


I have had a thought of using a couple of railblaza mounts on the akas which are redundant due to the theft of my rod mounts. If i can make up an adapter to take the spinlock swivel cleats. Or perhaps just screw them on to the star port.

CC

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