Steering Cables - Steel or Stainless Steel ?

[osirissail]

I would tend to agree with david samuelson, using high mod line versus stainless steel wire would require making sure that each turning sheave/block is smooth and clean and the right diameter. Considering that most of the installations on boats have the wires/cables/etc. running through bilges and other dirt prone areas I would be hesitant about using high-mod lines versus stainless steel. Dirt working its way into the high-mod line would facilitate internal breakage or cutting of strands.
- - Same with stainless versus galvanized or normal steel cables. The environment down in the bilges is rather high moisture and low ventilation so I would be constantly worrying about corrosion/rust. And the quality of galvanizing these days leaves a lot to be desired, witness our anchors and anchor chains. And galvanizing is a coating on the surface of the wire which will/can be worn through by frequent travel over sheaves/pulleys and through bulkhead openings.
- - Using stainless cable is the "easy" way to do the job and then basically forget about it until you get an indication something needs adjustment.

[sailorchic34]

Well the Engine compartment is normally pretty dry/ well ventilated with two cowl vents aft, no water in the bilge Engine exhaust is not a problem as the exhaust is facing the bow (darn V-drive) and routed far away from the steering.

I DO need to check that all the sheaves turn and pull the pins the sheaves turn on too. So not looking forward that that. Way to greasy for my tastes, but I wanted to live and sail on a boat. I do worry about creep in the high mod line. It's not easy reaching the far side of the quadrant for adjustment

[DeepFrz]

From the Amsteel Blue web page; "Similar elastic elongation to wire rope" and "Very low stretch" (whatever very low means).

[sabray]

Originally Posted by sailorchic34

Well the Engine compartment is normally pretty dry/ well ventilated with two cowl vents aft, no water in the bilge Engine exhaust is not a problem as the exhaust is facing the bow (darn V-drive) and routed far away from the steering.

I DO need to check that all the sheaves turn and pull the pins the sheaves turn on too. So not looking forward that that. Way to greasy for my tastes, but I wanted to live and sail on a boat. I do worry about creep in the high mod line. It's not easy reaching the far side of the quadrant for adjustment

Mine are no where near the bilge and look like new after 4 years of service. Yes they have to be checked but you should be checking.g your steering gear anyway. For my installation it was the better choice so far it's been fine.

[neilsailingrn]

Is that Dynex Dux Jedi? Looks impressive. Why use stuff that can corrode when something like this exists!

[perchance]

Does anyone know if synthetic line is subject to chemical attack from Hydrocarbon fumes produced from diesel fumes or oil and grease etc.?

[Saltyhog]

It would be interesting to know what the folks at Edson would have to say on the subject of galv. vs. stainless vs. hi-mod.

[osirissail]

Originally Posted by Saltyhog

It would be interesting to know what the folks at Edson would have to say on the subject of galv. vs. stainless vs. hi-mod.

I would suggest that they would say - "We will sell you whatever sheaves, etc. you want for a system . . . " but would absolutely be extremely non-committal about the choice of "galv vs. stainless, vs hi-mod" - doing so would make them legally liable if the system is not appropriate for your boat and causes serious problems or injuries.

[Capt Phil]

Sailorchic34, I would go with galvanized... think about how long you are going to use the boat and ensure that whatever you select lasts twice that long. If you have a rigging shop recut, splice and/or install, have them also put up a spare set made of plastic covered galvanized wire along with a set of new clamps.
I had the misfortune of having to replace the steering cable on a CT 41 in the middle of a storm sea years ago and had to fabricate a new steering cable out of that stuff. It was sloppy but got us into port 3 days later for a proper fix. The cable snapped because I lashed the wheel down and the sea just picked the boat up and slammed her down sideways, so something had to give... live and learn. Not my Boat! Just delivering her north. Capt Phil

[tropicalescape]

Originally Posted by perchance

Does anyone know if synthetic line is subject to chemical attack from Hydrocarbon fumes produced from diesel fumes or oil and grease etc.?

I know that arimide fibers and gasoline dont get along with each other...DVC

[Stumble]

I actually joined the forum just for this thread, so bear with me a bit, I will try to address a number of things that were brought up.

1) dyneema is a very well settled material for steering cables. Most of the Open 60 class are using it, as well as a number of production shops are moving to it. This is not. A new application.

2) dyneema is almost chemically inert. With the exception of Extremely strong acids. When ph approaches .25 it starts to have an effect, but there is nothing on a boat that should ever get close to this PH. Diesel fuel, gasoline, acetone, kerosene, ect have no appreciable effect on dyneema.

3) creep in this application is again not an issue. Creep is the long term elongation of a substance due to permanent deformity. In dyneemas case it takes loads in excess of 10% of its MBL applied constantly to have ay appreciable creep. At 10% MBL applied 24/7/365 you should see about .1% creep per year. Since the typical steering cable is tensions to less than 50lbs it isn't in the same relm as what would induce creep.

4) splicing eyes in dyneema with a fid takes about 30 seconds (yes seconds). It takes longer to do the lock stitch than the splice itself. Way easier than double braid nylon.

5) while dyneema can be cut by abrasion, it is the most abrasion resistant fiber on the market. Actually more abrasion resistant than steel for the same fiber size. Reasonable efforts to deal with damaged sheaves should be taken, but the same is true if you replace wire with wire.

6) bend radius for dyneema is the same as for all line, roughly 8:1. Wire is typically 40:1. So anything wire can run through without a problem dyneema can as well.


The major problem with dyneema is that it is heat sensitive. At tempratures beyond 215 F, the material melts and looses massive amounts of strength permanently. Thus while it is a very suitable replacement for stearing cables, if those steering cakes run near the exhaust it wouldn't be good there.

[osirissail]

Excellent post, Stumble. But a couple of things and a question.

First the question - how does dyneema line hold up when impregnated with salt crystals? Over time just about every form of line on a cruising boat gets impregnated with salt crystals and ends up getting very stiff. Then flexing of the line starts the process of strands getting cut by the crystals.

Along that vein of thought, the cruising world is a "pig-sty" compared to the competitive yacht racing world. Dirt and grit and oils, assorted chemicals and hard objects manage to find their way into or on just about everything. For instance, something stuffed into a lazarette that happens to have the steering cables passing through invariably ends up resting or touching the cables until the next time somebody needs to use the offending item.

So how would the application of dyneema steering cables be realisticly affected by being used in the normal cruising "pig-sty" environment?

[Stumble]

Osiris,

A very fair question. That raises a couple of separate issues.

1) Salt crystals cause damage on board boats in a couple of different ways, and it is important to know how those salt crystals do damage to appreciate how to deal with it.

For steel salt's damage is caused by its hygroscopic nature. The salt actually pulls water out of the air, right up against steel, and it is this water that then causes it to rust directly underneath the crystal. The only way to remove it is to clean off the crystal itself.

On stainless you have the same problem as above, plus the fact that stainless steel when underwater is actually less noble than when it is dry. So you have a very small area of lowered electrical potential touching an area of higher potential, with an electrolyte in contact with them.... This is a battery, and causes both rusting of the steel, and micro pitting. This is the cause of crevice corrosion, which is what makes old stainless even if it looks ok hard to trust.

In dyneema you eliminate the above, but add the abrasive nature of a crystal impregnated in a line. This can be highly abrasive to stranded lines and is a real concern, but dyneema has a few advantages over most lines that really help here.

1) it has a cooeficient of friction about half that of Teflon. Which means that It is actually more slippery than Teflon. This helps keep the crystals from being able to cut into the fibers themselves since they just slip between the fibers.

2) dyneema is incredibly hard to cut. Because of its chemical structure dyneema is one of the most cut resistant materials on the planet (actually dyneema is more abrasion resistant than steel if the threads are the same size). Salt crystals just don't have the abrasion power to cut the line under the forces experienced in a stearing cable. At least not on a scale that is dangerous to the structure of the line itself.


As for line stiffining - unlike most lines that absorb water, dyneema is hydrophobic. Which means that water is not absorbed by the fibers itself. So you don't get the same types of deposits in the line as you do on say Sta-set after a few years. My 3 year old halyards are just as soft and supple as they were the day they went into service.

In day to day use aboard cruising boats it depends on the application, but there are a few things to keep in mind. First it doesn't require regular greasing like steel steering cables do (everyone does grease the cables as per manufacturers recommendations right? ). So you eliminate one point of grease on the boat and it's contamination, since dyneema is self lubricating (that coefficient of friction again). Secondly it does fine in dirty environments, none of the chemicals found on a boat will effect it chemically, though keeping it clean is always a plus.

As for stuff rubbing on it... I wish I could post the pictures of where my life lines have rubbed a hole in the piling near my boat. The line looks fine, but there is a 3 inch wear spot in the wood.

In tug boats dyneema lasts about twice as long as steel cable when used a tow hawsers. This is one of the dirtiest jobs on the planet. The same is true for pulling trees through Oregon forests as lashing lines (if you have ever watched that show axe men, some companies have replaced all their steel with dyneema and getting much longer life's out of it than steel). I could go on, but you get the idea I hope.

Finally on cruising boats there is now a recommended replacement interval of 8 years of Dynex Dux (heat treated dyneema that is stiffer and stronger) standing rigging. This is compared to the 8-10 year replacement interval of stainless standing rigging depending on type of fittings used.


Finally dyneema is incredibly easy to splice. It takes no tools, no particular skill, and just a quick explanation will have most people performing professional quality splices in just a few minutes. This means that the 200' 1/4" piece I carry in my sail bag can be made to do duty for pretty much anything on board in minutes. And is amazingly cheap (about 1/2 the price of sta-set for the same MBL, so it doesn't have to be wished over or considered 'racing gear to expensive for cruisers' .


It was pointed out in a PM to me that commercial advertising is only allowed in certain parts of the forum, and that I seemed to be running afoul of this. So let me be clear, I am no longer a professional sailor, though I did work my way through college and law school as a rigger/paid crew on race boats. But I have no financial interest in dyneema or anything else people use on their boats. Unless you sue a manufacturer and happen to ask me to represent you.

[Stumble]

Just a quick follow up.

Dyneema comes in a number of different flavors.

Spectra - is the same thing as dyneema, I mean exacally the same. The different names have to do with a marketing agreement nothing more.

Sk-60 up through SK-90 are all basically the same, though the manufacturing process keeps getting refined. Higher numbers are better, though more expensive. With the exception of

SK-75 - also known as Dynex Dux. This is the same fiber, that is then heat treated and annealed making the line MUCH stiffer, stronger, and more creep resistant. It is the only dyneema that should be considered for standing rigging. For all other applications it depends on which recomendations you read, but this stuff does need large diameter bends, so it can't handle eye splices without thimbles, or be spliced around a pin without radios protection like the other dyneema can.

[zeehag]

i like my ss steering cables just fine.....they work