Stainless steel wire is a flexible and robust form of rigging with many different applications and termination solutions. Whether your yacht uses 1x19 stainless or Dyform wire witheither swage or swageless fittings, inspection procedures at regular intervals are still critical, and typical life expectancy factors apply.
When inspecting wire cables and their associated fittings, it is important to look for signs of corrosion, rust or pitting. Due to the natural flow of water down the wire, the lower terminals tend to exhibit these signs before the wire itself. Water and debris can collect in these fittings and generate corrosion from the inside, thus compromising the wire captured within the fitting or the fitting itself.
Both rotary and roll swaging are strong and efficient forms of termination utilizing a machine that compresses the fitting sleeve on the wire. Roll swaging, when done properly, leaves two «flash» lines on opposite sides of the fitting sleeve. These lines appear as raised ridges with rounded edges and are typical of this technique.
Occasionally terminals will be rolled several times in order to reduce the «flash» lines. This situation hardens the terminal and creates the possibility of cracking because of over-hardening. It can also be the source of crevice corrosion because of the creation of microscopic folds in the steel and can be a source of staining on the wire or terminal.
When monitoring swage fittings, pay careful attention to the inside edge where the wire exits. If there is any evidence of cracking, it is an indication of interior crevice corrosion. Depending on the method in which the wire was prepared prior to the swage being done and what predominant environmental conditions the boat has seen, these cracks could appear in as general rule, we recommend little as 1-2 years.
We recommend careful inspection visually or with a die penetrate test to insure the safe and prolonged use of swage terminations.
Norseman Swageless terminals are manufactured with 316 Stainless Steel and generally have a life span greater then the wire they are terminating. This lifespan can last through a wire re-rig, but we recommend the replacement of the internal cone with each inspection. It is also important to carefully inspect the socket internally for signs of wear, and any sign of cracks would require replacement of the whole assembly.
We recommend careful visual inspection to insure the safe and prolonged use of swageless terminations.
Wire inspection can be done visually and should include a close inspection for corrosion, pitting, discolored strands and cracks at fitting exit points. Rust on the wire generally comes from the fitting and bleeds down the individual strands of the wire. This phenomenon is called «rougening». Pay close attention to wire exit points from all terminals as broken strands or «metal hooks» are a sure sign of fatigue failure. We recommend replacement of the wire if any broken strands are found.
Wire life expectancy
There are many variables to consider when it comes to the longevity of the wire rigging being used with todays modern mast systems. The most prominent factors are:
The amount of time and/or miles the yacht has been in service – as a general rule , we recommend complete Level C inspection (see Inspection Tables) of mast and rigging systems after a maximum of 40000 sailing miles or 6 years, whichever comes first. This comprehensive maintenance schedule would include inspection of the mast, wire, turnbuckles and their screws and all associated fittings. We recommend replacing the turnbuckle screws after a maximum of 40000 sailing miles or 6 years (whichever comes first). The screws may last for many additional years, but it is much less expensive to replace a few rigging screws than to replace the mast and all of the rigging.
What loads are put on the wire in comparasion to its breaking strenght – production and custom cruising yachts tend to have high safety factors in their rigging because chosen wire sizes are typically very conservative, so rigging loads are generally 15-25% of the breaking strenght during normal sailing conditions. However, some boat builders have been known to use smaller sized rigging with less of a safety factor to reduce production costs.
The yachts predominant sailing conditions – if the yacht is predominantly sailed in heavy air conditions, the life of the wire will be shorter than if the boat was sailed infrequently or in lighter wind conditions. The higher the rigging is stressed on a regular basis, the shorter its life span will be.
The amount of care and maintenance given to the rigging – if the rigging has been periodically checked, the end fittings rinsed with fresh water, and general care and maintenance have been employed, it will last longer.
How environmental conditions can affect the rigging
A major consideration in the longevity of the rigging system is the environmental conditions the yacht is subjected to. If the yacht spends most of its time in an environment with substantial air polution, contaminants in the air will generally shorten the mast systems life span, and frequent cleansing and inspection routine (Level A – see Inspection Tables) should be a part of your regular schedule.
Monitor those T-hooks
one popular fitting that requires more diligent survey and potential replacment is the T-hook. Due to its design, it is typically one of the few fittings with a life expectancy dramatically less than the rod or wire. When inspecting the T-hook, look for cracks on the iside of the sharp bend, as this is a typical spot for fatigue cracking. T-hooks must be diligently monitored and depending on the application should be replaced approximately once per year depending on usage, mileage and sailing conditions.
We estimate a life expectancy schedule based on climate variables and water salinity:
Heath and water salinity at maximum – 5-10 years
Heath and water salinity at medium levels – 10-15 years