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-   -   Splicing vs Swaging in Galvanized Rigging (http://www.briontoss.com/spartalk/showthread.php?t=2791)

dlochner 01-12-2016 01:31 PM

Splicing vs Swaging in Galvanized Rigging
 
An organization that I support has inherited a partially complete 65' LOD steel hull gaff rigged schooner. The goal is to qualify for USCG Certification as a Small Passenger Vessel.

The current standing rigging is galvanized wire with eyes swaged at the ends. The USCG suggested that we might want to consider an alternative method that is more in keeping with accepted practices. The inspector was not more specific; I assume he meant that the eyes should be spliced and not swaged. (The swaging looks like it is more typical of rigging completed for the construction and lifting industry, not for marine applications.)

I'm trying to understand why a splice eye is more desirable than an eye that is swaged or bull dogged. The three reasons I have found thus far are:

Swaged fittings subject the wire to work hardening at the end of the fitting because the swage is not flexible thereby weakening the wire.

Spliced fittings are more flexible, thus there is less likelihood of work hardening.

Splices spread the load over a longer section of the wire making the splice stronger than the shorter swaged fitting.

My questions, are these assumptions correct? If not, what are the reasons for using a splice instead of a swage? Are there additional reasons for using splices instead of swages?

Unfortunately I do not have ready access to the standing rigging to obtain dimensions. As I recall the rigging is about ⅜" and the swages are about 3" long.

Thanks!

Brion Toss 01-13-2016 04:08 PM

It depends
 
Hello,
And first, congratulations on being involved in what sounds like a lovely project. Your assumptions aren't exactly correct, but they are worth looking at. Strength, at least as measured on a testing machine, will be about the same for a splice or a swage IF both are done optimally well (also true for proper seizings, and poured sockets). Long-term fatigue resistance might give the nod to the splice, but only where fatigue loads are severe. The one place where such is liable to be the case is for the swages that form soft eyes, at the tops of the wires. Here there can be significant lateral loads, and swages will tend to break the wires there. If you make the eyes longer to relieve this, you can get a sloppy fit, with too much rig motion from tack to tack. If you have lugs or tangs aloft, this isn't an issue, as the lead on a thimble is kinder. It is also difficult to seal swaged wire with service, but that is a separate matter.
If the Coast Guard person's suggestion wasn't about structure, then they would have had a really good argument based just on aesthetics. Swaged schooner rig looks a bit, um, agricultural, and even uneducated passengers are likely to notice this.
Most bulldog clips, by the way, weaken wire significantly, look even worse than swages, and love to snag things.
Fair leads,
Brion Toss

dlochner 01-29-2016 07:18 PM

Brion,

A too long delayed thank-you for your response.

To pick up on your agricultural theme, some of the pins look to be tractor hitch pins. Not something that would necessarily inspire confidence although in an emergency might be just the device.

Dave


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