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Old 02-06-2014, 23:09   #16
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Re: Rod Rigging Life?

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Originally Posted by Stumble View Post
Frankly I wouldn't go back to rod on a cruising boat. The marginal benefit of windage compared to the extra risk of the rod frankly just don't seem to be worth it. But then I wouldn't switch to wire either.

When we had to replace the rig on our boat we switched the entire rig to Dynex Duc rigging. Not only does it really make a difference in how the boat feels, and was actually less than wire it is also completely replaceable anywhere in the world.
How does it make a difference to how the boat feels? What is the life compared to wire? Is it still cheaper if you take into account more frequent rigging (if in fact it is shorter life)?
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Old 02-06-2014, 23:12   #17
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Re: Rod Rigging Life?

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Originally Posted by Jim Cate View Post
Jr, I'm not sure where I got the idea that you were sailing a Niagara 35! Sorry about the confusion... the Little Harbour is a very different boat, especially if equipped with an extra big rig. But I still doubt that there would be a significant loss of performance in a cruising environment if you went to Dyform.

Cheers,

Jim
I'm the guy with the Niagara 35 and you were answering my post. I'm just swooping in and stealing all the good answers from jr! Sorry if I added confusion.

My Niagara has 33 year old original rigging but wasn't worked too hard, I don't think, based on the condition of the rest of her. Still high on my list of big ticket items to budget for. Did the engine this year.
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Old 03-06-2014, 02:57   #18
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Re: Rod Rigging Life?

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Originally Posted by neilpride View Post
.. most rod failures are fatigue induced , at the head.. first a micro crack and later the rod part at the head.
Actually the failure mode is not fatigue usually, it is crevice corrosion and SCC. So the factory say.
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Old 03-06-2014, 02:59   #19
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Re: Rod Rigging Life?

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Originally Posted by Stu Jackson View Post
That pretty much sums it up. Unforecast potential catastrophic failure on a cruising boat? Hmm....

Good luck in your choice.
Reminds me of the keels issues. Not just a coincidence.
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Old 03-06-2014, 03:17   #20
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Re: Rod Rigging Life?

Quote:
Originally Posted by Stumble View Post
Frankly I wouldn't go back to rod on a cruising boat. The marginal benefit of windage compared to the extra risk of the rod frankly just don't seem to be worth it. But then I wouldn't switch to wire either.

When we had to replace the rig on our boat we switched the entire rig to Dynex Duc rigging. Not only does it really make a difference in how the boat feels, and was actually less than wire it is also completely replaceable anywhere in the world.
I can't make Dynex work. Pity as it has many attractions. Creep is an issue with high preloaded stays needing adjustment. Stiffness is lower unless enormous thickness is used (with windage issues) and a different coefficient of thermal expansion between the mast and rigging is a problem requiring adjustment when going from tropical to temperate climates. It is not as tough as steel so no good for furling stays. Life seems no better UV reducing strength fast. Also the back stay antenna is much neater in rod/wire.
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Old 03-06-2014, 03:30   #21
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Re: Rod Rigging Life?

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Originally Posted by jr_spyder View Post
A smart and conservative manufacturer wouldn't differentiate between usage for racing or cruising. They's just pick the worse case and use that as the baseline usage. In fact they would probably take the worse case, figure the max number of serviceable years for that case, and then cut that in half (at least) ...
They actually do make a flexible allowance for this in their recommendations by limiting life on mileage or time, the lesser of the two, with a further reduction for race boats and discretion to account for climate and fresh/salt water use. It's all covered quite well I think.
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Old 03-06-2014, 03:49   #22
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Re: Rod rigging life?

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Originally Posted by Ann T. Cate View Post
We were told by a rigger at Svendsen's in Alameda, CA, that the Nichronic 50 alloy was good for 20 yrs., so I think sailorboy1 has the right of this...
It can last 1000 years in my house. 6months in a salt bath. Navtec clearly advised me 12 years give or take a bit. They are the people most likely to know best.

They have a difficult balance to find between keeping customers happy by letting them keep their rigs a long time and in preventing reputation damage by not allowing customers to keep rigs too long and preventing rigs collapse. I am inclined to believe what they say.
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Old 03-06-2014, 17:03   #23
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Re: Rod Rigging Life?

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Originally Posted by cwyckham View Post
How does it make a difference to how the boat feels? What is the life compared to wire? Is it still cheaper if you take into account more frequent rigging (if in fact it is shorter life)?
1) it removes about 90% of the weight of the rigging. Since that weight is so high it makes the boat stiffer. On the small trimaran it is actually noticeable.

2) about the same as wire (as recommended) probably shorter in reality.

3) much cheaper. At the first refit it came out the same. After 7 years you replace all the rope for a couple hundred bucks, but the fittings are reusable forever. Since they are aluminium instead of stainless there is no worry about crevice corrosion.

4) my guess is that it won't last as long as wire does, but will last about as long as wire is recommended to.
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Old 03-06-2014, 17:12   #24
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Re: Rod Rigging Life?

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Originally Posted by poiu View Post
I can't make Dynex work. Pity as it has many attractions. Creep is an issue with high preloaded stays needing adjustment. Stiffness is lower unless enormous thickness is used (with windage issues) and a different coefficient of thermal expansion between the mast and rigging is a problem requiring adjustment when going from tropical to temperate climates. It is not as tough as steel so no good for furling stays. Life seems no better UV reducing strength fast. Also the back stay antenna is much neater in rod/wire.
1) Dynex is sized for creep not strength. Typically creep is designed to remain at less than .1 inch per year. Which doesn't require much in the way of regular adjustments. The heaviest loaded boat I know of using Dynex is in Open 60 that runs 50,000psi of rig tension applied with a hydrolic ram. It worked fine and didn't have creep issues. But then it was sized properly.

The upside of sizing for creep is that you wind up with a line that is 2-3 times the strength of the wire it replaced.

2) stiffness isn't really a concern.

3) the thermal delta is a real issue for people who regularly have wide temprature changes. But it isn't a daily issue. I tune the rig to frequently to even notice the difference to be honest.

4) absolutely true. Figuring out how to make it work on furling sails hasn't happened to my knowledge.

5) lifespan is going to be dictated by UV damage. Right now the recommended replacement interval is about 7 years in the tropics. But because the line is so much stronger than the wire that was there at no point is the strength less than wire.

For me UV damage is a much better villain than stress crack corrosion, since it is easy to see the UV damage, while SSC is a hidden killer.

6) for an antenna just bury a thin wire in the middle of the line. It acts an the insulator. This is actually better since you don't need to deal with a slit backstay.
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Old 03-06-2014, 17:36   #25
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Re: Rod Rigging Life?

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Originally Posted by poiu View Post
Actually the failure mode is not fatigue usually, it is crevice corrosion and SCC. So the factory say.

No, whatever the factory say, we have in the shop a bunch of old rod coils , some heads are cracked and no corrosion isues found, even we cut the heads to see if we found some clean metal and yes we found it, shiny clean metal , tipical old tang fittings and spreader tips conections are the focal points, i mean the top heads are hide inside of a cone fiting and screwed with a bronze lock nut very similar to a stalock fitting, the bronze fitting crack to in some instances , or the head at the tops work free in a stemball ss fitting , in this case you can see the head, its exposed.. the bottom heads are hide under the turnbuckle , the heads are solid , no crevices or flaws to allow rust to eat the metal like in a swage wire terminal, we replace yards and yards of rod for wire for some customers, we even reuse the rod to fabricate babystays or even chainplates ,rod fail by load cycles my friend, load and unload a rig for xxx cycles determine how soon or late the crack start to grow, corrosion and rust its posible if the spreaders tips are covered with tape or other funy chafe protection and the turnbuckles , special the old style navtec turnbuckles are a water trap, with a regular maintenance , rinse the bottom end with fresh water and visual inspections at the spreaders tips and tangs conections can last longer..
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Old 04-06-2014, 17:21   #26
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Re: Rod Rigging Life?

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Originally Posted by Stumble View Post
1) Dynex is sized for creep not strength. Typically creep is designed to remain at less than .1 inch per year. Which doesn't require much in the way of regular adjustments. The heaviest loaded boat I know of using Dynex is in Open 60 that runs 50,000psi of rig tension applied with a hydrolic ram. It worked fine and didn't have creep issues. But then it was sized properly.

The upside of sizing for creep is that you wind up with a line that is 2-3 times the strength of the wire it replaced.

2) stiffness isn't really a concern.

3) the thermal delta is a real issue for people who regularly have wide temprature changes. But it isn't a daily issue. I tune the rig to frequently to even notice the difference to be honest.

4) absolutely true. Figuring out how to make it work on furling sails hasn't happened to my knowledge.

5) lifespan is going to be dictated by UV damage. Right now the recommended replacement interval is about 7 years in the tropics. But because the line is so much stronger than the wire that was there at no point is the strength less than wire.

For me UV damage is a much better villain than stress crack corrosion, since it is easy to see the UV damage, while SSC is a hidden killer.

6) for an antenna just bury a thin wire in the middle of the line. It acts an the insulator. This is actually better since you don't need to deal with a slit backstay.

I can see the arguments for it. I wonder why it is so slow to be adopted amongst cruisers? Have some people found important problems? What don't some people like otherwise?
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