Swageless Mechanical Fittings or Swage Terminals…

…Which do you prefer?

When talking about wire standing rigging for sailboats, there are two primary ways to secure a fitting to the end of the cable, the swage fitting and the mechanical fitting. One requires a specialized, expensive machine (pictured below) that is used to essentially squeeze or hammer the fitting onto the wire, this is called the swage fitting. The other simply requires the use of some wrenches (a vise is a great tool here too), some thread locker, a bit of patience, and some experience wouldn’t hurt either ;0). The latter is referred to as the mechanical or swageless fitting.

SWAGE FITTINGS:

High quality swage fitting manufacturers used by The Rigging Company (TRC) include: Hayn, Alexander Roberts Co., Stalok, C Sherman Johnson, Global BSI, and up until recently Gibb a parent company of Navtec. A swage fitting has more length and is a slimmer design than the equivalent swageless fitting. Swage fittings have a long drilled shaft relative to the wire’s diameter (diagram 1). The depth of the shaft dictates how much wire will end up buried inside of the fitting prior to swaging. Once the wire is inserted into the fitting, the fitting is then rolled through (or hammered by) a set of dies, to squeeze the fitting onto the wire. The machines used to do this can be very expensive, from $5k to $50k and up…dies not included.

Yes, there a few other types of swaging techniques which we might save for another time. One of which we commonly refer to as the “Nico Press”, a generic term. This is an entirely different ‘box of frogs’ all together. If you are interested read more on that here, written by our friends at Sailing Services.

[youtube https://www.youtube.com/watch?v=cLM-crQeN-A&w=560&h=315]

SWAGELESS (MECHANICAL) FITTINGS:

Our favorite high quality mechanical or swageless terminal manufacturers are: Hayn Hi-mod and Stalok. Let us not forget Noresman (Navtec), one of the more popular fitting manufacturers on the market up until recently, as they have since shut down production. A mechanical fitting is typically a three part fitting (sometimes four). This type of fitting does take a bit longer to execute than the swage fitting, even by the most experienced of rigging technicians. The real bonus here is it does not require a ridiculously expensive machine. Which makes it a very appealing product for the DIY project.

.[youtube https://www.youtube.com/watch?v=QTGB_kfTxUg&w=560&h=315]

PROS AND CONS:

There does appear to be some controversy about which type of fitting is better, so I’ll try to clear things up a bit. Let’s take a moment to talk about the pros and cons regarding these two styles of wire terminals. Swage fittings require one of these expensive machines, so you will likely have to pay someone to do it for you. Whereas Mechanical fittings can be the perfect solution for the DIY sailor. Swage fittings are substantially less expensive than mechanical fittings. For example, a swage stud for 1/4″ wire with 1/2″ thread retails for around $25 and the comparable mechanical fitting retails around $75. Multiply that times the amount of fittings you’ll need and it can make quite a difference in price when replacing an entire rigging set.

The swage fitting is more likely to suffer from metal fatigue issues like cracking as the metal is being cold formed during the swaging process. Mechanical fittings do not have this problem. Therefore it is a general consensus that a mechanical fitting will last longer than its swage style counterpart. However, if I had to pull hairs I’d say that the wire strands are a bit more stressed with mechanical fittings (caused by the forming), instead of the fitting itself. Hayn tried to combat this with their Hi-mod design in using their “Crown Ring” to keep the cover strands straight instead of bending them over the end of the cone (wedge).

Having said all of that, a properly made swage fitting will last about 7-20 years or roughly 25,000 nautical miles, depending on geographical region and use before replacement is recommended. Regular inspection, regardless of fitting choice, is always recommended with service intervals around every 3-5 years.

Mechanical (or swageless) fittings are not without their problems either. We just completed two recent jobs with mechanical fitting failure; one where the toggle straps cracked on multiple fittings, not so much where the wire goes into the fitting (although that has also happened), but the jaw of the fitting itself… fatigue. The other job was on a furler where the mechanical eye fitting at the top of the stay, came unscrewed by the spinning action of the furler. So, unfortunately there is no perfect solution.

We, at TRC, recommend using swage fittings over mechanical fittings when the stay is rigged with a furler, i.e. forestay.

There are also hybrid sets made, utilizing both types of fittings, with Swage fittings at the top of the stay and mechanical fittings at the bottom. This is the meet in the middle solution when price becomes a factor. Also this method is commonly practiced when building new masts.

TRC has had great success with the longevity of our swage fittings over the years {knocking on wood}. I’d say this is attributed to the use of high quality fittings, wire, the right machines, as well as proper execution. We end up selling mostly complete rigging sets using swage fittings. When discussing options with our customers we can really only justify the additional cost of mechanical fittings when the boat is going to endeavor on high mileage journeys. This way the wire can be replaced, the fittings inspected, and re-used with new cones (wedges). One of the other big benefits of mechanical fittings is/was at sea repairs. As the sailor could use wrenches and some Loctite to terminate a new cable at sea if needed, but not without the purchase of some good quality wire cutters (not cheap). With developments in synthetics we think that this problem can be much easier overcome with the use of Dyneema or Vectran. We offer a TRC Spare Stay Kit specifically for this purpose…no tools required!

Either fitting, if not made properly, will have issues and can cause failures. Conversely, when done properly, either of these fittings will provide the boat and its crew with many years of trouble free service. With either fitting, given that they were executed properly, age, geographical location, and wear are the biggest enemies for standing rigging longevity.

RIGGERS TIPS FOR MAKING UP SWAGELESS TERMINALS : 

First, when choosing a mechanical fitting ensure that it is for the correct wire type being used, i.e. 1×19, 7×19, and Dyform/compact strand. You’ll need to disassemble the mechanical fitting (with Sta lok you can leave the former inside of the fitting) and then read the directions which should be included (or can be found online). The general gist for any mechanical fitting (regardless of manufacturer) goes as follows: start with a nicely cut end of wire. Then the socket portion of the fitting gets slipped onto the wire.

Next, the end of the wire must be unlaid evenly (the tricky part), so that the core strands are exposed and the cover strands are evenly splayed open.

Once that is done, the cone (or wedge piece) is pushed onto the core strands. With the outer wires surrounding the cone evenly, work the socket back up to the end of the wire, and re-lay the cover strands onto the core. Do this until the outside strands protrude from the end of the socket evenly and parallel (as pictured below), and the socket cannot slide up any further.

 This is all done while keeping the cone (or wedge) appropriately submerged below the end of the cut wire by the recommended amount. The amount of core stick out varies by fitting manufacturer, so read the directions and follow the guidelines closely. The outer wires cannot be flared out (see diagram 2) and must be parralel or curved-in slightly. You will not be able to assemble the fitting properly (or at all) if you don’t get this step right. Now, (unless using a Hi-Mod fitting for which you will need to rig their “Crown Ring” in place) you are ready for the fitting to be screwed together and to form the wire. To do this we use Loctite primer and red Loctite to help lubricate things as shown in the video above.

WARNING: stainless on stainless will gall (or cold weld) with too much friction and you’ll have a fitting that can’t be screwed-on OR off. 

Once screwed down completely we recommend that the fitting be unscrewed again before the Loctite activates (so hurry depending on temp) and checked for proper forming of the cover (outside) strands. Lastly, if all looks to be fine, we coat the threads with more red Loctite and then screw it back together tight!Some manufacturers recommend the use of sealants along with Loctite into the fitting before the final assembly to mitigate water intrusion and to help secure things. Recently it seems that most manufacturers are getting away from this, perhaps because of oxygen deprivation causing corrosion. So again, please follow the instructions and guidelines that come with the fittings that you have.

…so there it is in a nutshell. As I always say, seek the council of your local rigger for product specific information as well as any tips and tricks so that you have it right.

Thanks for the read and leave us your comments below.

~T.R.C.