Salty Metal: Replacing Rusted Rudder Cables with Spectra* (Plastic)

Did you know we live in a mostly metallic world? That salt you like to shake on your dinner?
Metal. That saltwater you like to play in? Metallic water. Those rusted rudder cables that snapped on you just when you least expected it? Rusted metal. So what is metal, and why do we think our stainless steel cables are strong, say, in comparison to plastic? If you've landed on this blog, it's because you like me need to swap out your rudder cables, and you've come across an alternative cable, likely named Spectra.

As you can see from this periodic table of the elements, most of our elements are metal. Loosely defined, a metal is an element that bonds atomically with itself in a fluid manner. Stainless steel is an alloy of iron and chromium as well as other metal elements namely nickel and molybdenum (Mo, number 42). What makes your rudder cable strong is not so much the willingness of its metal elements to bond to one another but the number of strands wound into the cable. Metal filaments can stretch and break quite easily, but wound together into a rope, like any other kind of rope, they gain strength. Like just about everything else also, when they flirt with omnipresent oxygen, oxygen steals their bonding strength. The red of rust is the bleeding, if you will, of the iron as it succumbs to oxidation.
Luckily I was playing around with my rudder cables on the dock when I had a rusty connection snap before I got myself into trouble on the water. Perhaps it wasn't so smart to rig up the loop with medical tape, but that's what I did. I was comfortable with knowing very little tension pulled the cables while steering. This comfort also helped me make the decision to switch from steel cables to plastic.
First Aid for Rusty Steering Cable
So, we basically know what metal is. What is plastic and what makes it strong? Spectra is a brand name, just like Dyneema, for UHMWPE or ultra high molecular weight polyethylene. What the heck does that mean? "UHMWPE is a type of polyolefin. It is made up of extremely long chains of polyethylene, which all align in the same direction. It derives its strength largely from the length of each individual molecule (chain)." This material has been around since the 50's and first commercialized in the 70s. Seen any rusty plastic floating around in your ocean lately? Me neither. Plastics are non-metals comprised of hydrogen and carbon, in this case long chains of bonded hydrogen and carbon. In our periodic table of elements, these are simpler elements number 1, H,  and 6, C.
I ended up choosing a reel of generic UHMWPE from a kite string company. You will find any number of UHMWPE lines on the market for spear fishing, etc., without the comfort of a brand name. But does your stainless steel cable that snapped have a brand name you trust? Probably not.
Curious Hand Written Specification
I visually inspected the fiber and found it appeared to be the same kind of product listed as Spectra or Dyneema. It had no give and was nearly impossible to cut with anything other than a fresh razor blade. As someone who has worked with wire rigging and synthetic rigging for the past twenty years, I know the only thing that will prevent any kind of line from failing under use is INSPECTION prior to use. There is nothing about this fiber that indicates it will fail spontaneously. This particular product was cost effective at $12.95 for 50 feet of 1.6 mm on Amazon.
At first I thought I'd be able to wrap the end of it to the broken stainless cable with electrical tape to pull it through the rudder line, but this product is very slippery.
Looks a lot like Spectra and Dyneema
I was on the dock scratching my head when I had the idea of using some of the shrink tube I had purchased to connect the two ends. I'd taken a variety of tools with me and was very grateful to have the clear tube. Success was mine a few minutes later.
The tools, including clear shrink tube at the top ($6.99 on Amazon)

The cable measured true to its specification as listed on Amazon and on the product
 Here's a video of me inspecting the line and trying to cut it. I was only able to cut it with a brand new sharp razor blade. This is good news, since it does not easily cut against an edge and gives me ideas about how to protect it from rubbing for final install. Anyone who has ever worked with mason's line, which looks similar from a distance, will see how taut this line is in comparison and how difficult it is to make it cut or even fray.

The clear shrink tube linking the two materials together for pulling
 My first tug through the cable tube failed, and I was surprised when I pulled the blue line out to find the shrink tube had slipped off the stainless. So, using a Bic lighter, I redid the shrink tube, shrinking the tube longer on the steel side. Plastic rope will melt easily, so I did not want to go overboard heating it on that end. I unspooled a decent length of the UHMWPE so there would be little resistance while guiding it through from the pedals to the rudder.

UHMWPE fiber and stainless pulled through. Success!
Some dirty water came out with it, and not only was the shrink tube joint intact, I could not pull the ends free by hand. I cut the tube and left the end on the fiber line. My confidence in the products was gaining by the minute. Soon I had both lines pulled and terminals protected by clear shrink tube. I'd spent considerable time reading up on tubes and finally went with clear so I will be able to see what is happening with the weak areas of my rudder lines. In the photo above you can see rust on the stainless.
Excess line pulled through at rudder

Excess line left at pedals
Stay tuned for the next post, which will cover sprucing up the steering pedals and rigging the rudder bar and pedals to the pretty blue line. Remember to check your steering line BEFORE you paddle each time, and you can pretty much guarantee you won't experience failure on the open sea.