2008 EZ-Slalom

The EZ-Slalom Stainless Steel Cable Mainline

Defining "HeavyDuty"

When you first see the words "heavy duty" the picture that most likely comes to mind is of something massive, strong, and obviously built to last. That's certainly what we think of anyway. If that's the picture you see in your mind you may be a bit surprised when you first see the stainless steel cable our slalom course mainlines are built from.

First off, the stainless steel cable we use to build our mainline is the same exact cable also used by our competitors. Same size, same strength, same manufacturer, same cable. How do we know this? We purchase our cable from the same supplier our competitors purchase from, who happens to be the largest supplier of such stainless cable in the United States. This mainline cable is 3/32" in diameter (coated to 3/16"diameter using a clear, flexible PVC coating) or about the size of #12 electrical wire. You're wondering how such small cable can possibly be strong enough to hold up under high tension for extended periods of time (several years) while immersed in water? So were we.

The manufacturers break strength rating for this cable is 920 pounds of tension. Pretty tough stuff, especially considering it's diminutive size. Not being satisfied with that we went the extra step of having this cable break strength tested to insure that it is as tough as advertised as well as to satisfy ourselves of its strength. To our surprise, despite the manufacturers rating the cable tested out to be even stronger than advertised! Of over a dozen samples tested the lowest failure rating for any of our samples was 1050 pounds of tension, easily well beyond the amount of tension required to keep your course dead-on straight. Certainly then, this cable while not being massive in size or diameter is definitely strong enough to meet anyone's definition of "heavy duty".

So What Makes Our Mainlines Better?

So if we use the exact same stainless steel cable to build our mainlines as everyone else uses, what makes the EZ-Slalom cable mainline different? Two words. Superior engineering.

EZ-Slalom Diamond Diagram

The most common way to attach two pieces of steel cable together is by crimping them together. No rocket science there. One of the main issues in designing a slalom course mainline is that where the buoy arm attaches to the mainline a structure of some sort must be created to stabilize the buoy arm perpendicular (that is, at a 90 degree angle) to the centerline of the mainline. This structure is known as the diamond due to the shape that is created when the buoy arm is attached at this point. The diagram above illustrates what the diamond looks like, how it's constructed, and how the buoy arm attaches to it. Basically you have one cable at the centerline of the course running from diamond to diamond positioning the buoy arms at their correct locations throughout the course. Where the diamond is located (where the buoy arm is attached to the mainline) you have that one cable attaching to two separate cables with each of the two cables attached to the buoy arm at either side of the boat lane section. See the diagram above for more detail.

How Do Others Do It?

Others attach the mainlines centerline cable to the cable sections that create the diamond using one crimp at each of the two end points of the diamond. They're connecting three cables together at this point, the one centerline cable intersecting with the two halves of the diamond. This one crimp is required to handle two different types of tension load, axial load and radial load. Axial load is the tension applied to the courses mainline to create and maintain linear tension on the mainline, which is what keeps the course straight. Radial load is the load placed on the crimp by the two halves of the diamond being spread apart at an angle to this same axial tension at each end point of the diamond.

Asking one crimp to take two different types of load at the same time, and placing that entire load on only one crimp is asking a lot of that one crimp. Especially if you use an aluminum crimp at this point. Aluminum is a relatively soft metal which when attached onto a dissimilar metal (the stainless steel) and then immersed in water (which aluminum crimps are not specifically designed for) is subject to galvanic corrosion, which can cause the eventual weakening and/or failure of that aluminum crimp.

How Does EZ-Slalom Do It?

With the EZ-Slalom HeavyDuty mainline we divide that load between two crimps rather than just one. First, we build each of our diamonds separately by using two sections of cable with each cable staggered so that it leaves a tail at each end point of the diamond (see the diagram above). So at the diamond's end points there are only two pieces of cable being attached together, not three. Building the diamond in this manner places the entire radial load on only one crimp at each end point of the diamond. We then attach the remaining tail at each end of the diamond to another cable which runs from diamond to diamond. This second crimp takes the majority of the axial load. Thus we divide the tension load placed onto the cable between two crimps rather than putting it all on just one, lessening the load on each crimp and reducing the likelihood of failure at any crimped point.

The crimps that we use for our EZ-Slalom mainline are themselves different as well. Where others use aluminum crimps not specifically designed for marine applications, we use a crimp made from hardened copper and zinc that is manufactured specifically for use in a marine environment. Again, to ensure their strength was up to the necessary standards we've had these crimps laboratory tested with our cable to measure and ensure their resistance to failure under tension. In all of the samples tested these crimps held at least as much tension as the cable did. Plus they're much more resistant to corrosion and therefore much less likely to fail. Better materials combined with better structural engineering, resulting in longer service life of the mainline and reduced likelihood of failure.

That's how we build all of our products at EZ-Slalom. We find the best available materials, combine them into the best engineering designs available, and price our products very competitively.

Best Built! Best Engineered! Best Value! That's why EZ-SLALOM is The Standard in Portable Water Sports Courses!

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