BEST OF 2014 – Refit Special – Not changing the boat? Then make it new! #1
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Control of the mast and rigging is essential because it accounts for 80-90% of the propulsion of a sailboat. To make sure there are no parts that need to be replaced, it is a good idea to dismast every four years to check the condition of the shrouds, all the terminals that attach the shrouds to the deck, and the spreaders. An analysis should then be carried out to check the maintenance status of the cable: if a replacement is needed, the best solution should be figured out depending on the boat. For steel and other modern materials (carbon, titanium, PBO, etc.), it is a good idea to include specific analyses in the maintenance cycles provided by the manufacturer: liquid penetrant and ultrasonic analysis are very low-cost operations when compared to the effect of the rig on the deck. 
The rigging, that web of metal cables that holds up the mast, gets tired. In fact, in technical jargon, it is precisely what is called fatigue stress that causes a steel cable to break. There are many factors that determine the life of a steel cable. First, how much is sized in relation to the actual maximum load it will have to bear. Typically, the rigging of a cruising boat is oversized by more than 15 to 20 percent of the actual tensile strength under maximum sailing conditions. This value drops by 50% in boats intended for racing. you should then keep a calculation of how many miles the boat has sailed under sail: usually after 30/35 thousand miles a complete and thorough inspection should be done, an almost certain replacement of rigging and some worn parts. Maintenance also needs to be taken into account; the cleaner it is kept from salt and weathering, the longer the rigging will have a long life. After four years, a complete inspection and possible replacement of the most stressed components is necessary. In case a rod cable was armed, it can be cut, repressed and still be used for a long time. The rod is a cold-drawn steel lever cable with much higher tensile strengths, at the same diameter with the spiroidal one, and lower elongation. Otherwise, if you mount spiroidal cable, which is cheaper, on board, this must be replaced. There are two types of spiroidal on the market. The most common is the classic 1×19 spiroidal: 19 strands of braided AISI 316 stainless steel. Robust and reliable and lower cost has high elongation and low aerodynamic surface. Dyform cables were born to overcome these drawbacks. They are still 19-wire spiroidals but different profile and size. The result is a more profiled cable that offers less wind resistance and has 20 to 30 percent higher breaking loads than the traditional 1×19. Only downside: it costs three times as much. Possibly, to save weight and improve performance, consider switching to carbon or PBO (textile fiber) rigging, which has high costs but almost no elongation. Our expert’s advice is to consider the latter option only if you are an experienced sailmaker: “There is no point in spending a lot of money on rigging in PBO if you are then unable to properly trim the sails. In a refit, there is no logic in replacing fixed rigging unless you recover the weight saved (e.g., in the keel) unless you want to gain righting. A different argument has to be made, however, for boats 20 meters and up because the weight you are going to save is really significant and allows you to spend less on deck equipment that will be able to be less expensive and smaller because it will bear less load. We always say that money spent up is saved down.”

As for aluminum shafts, on the other hand, apart from failure of rigging, the most common cause of dismasting is weakness of the metal due to denting or corrosion, leading to loss of its structural integrity. Rarely does one have to intervene with a total replacement of the structure; often, even during refit work, a few targeted checks and interventions are sufficient. The shaft is basically a pole subject to compression, so a dent amplifies the entry forces in that area, creating a point of weakness. If you find a dent or bend in the shaft, you’d better examine it thoroughly. The solution differs depending on where the dent is located, how deep it is, and how close it is to important load bearing areas. The best repair is to fix one plate of the same metal on the inside and one on the outside. Sometimes, when the dent is in the middle of the tree, you cut it at that point and remove it. Then a collar is put inside the shaft and fastened with rivets on both sides of the joint. For smaller dents, however, an outer plate with rounded corners is sufficient to avoid hard spots. So there is no need to access the inside of the tree. Some on-board repairs are done with epoxy, although aluminum reacts badly with some chemical compounds and the repair lasts a short time. In fact, repair with putties could mask, especially in case of corrosion, the severity of the problem that would be mistakenly given as solved, while instead it could continue under the epoxy patch (after the repair one would have to anodize again or if the shaft is painted restart from the epoxy primer). Corrosion is a very common problem and occurs when using dissimilar metals-for example, stainless steel screws on an aluminum shaft. Beware, therefore, of white powder that settles around the fasteners of spreader terminals, winch bases, lights and other terminals: this is an oxide caused by metal disintegration. Also be careful when mechanically attaching (with rivets or otherwise) anything to a material with different electrical potential: always use insulating pastes such as Duralac or Tuff Gel. A simple aluminum blanching can become a very tangled skein to unravel: even if the area of corrosion is circumscribed, action must be taken to prevent the corroded areas from moving even a few inches. It is not hard to imagine the difficulties of disassembly (steel and aluminum weld over time) and reassembly (threads, insulation) of this work, but it is very difficult to be able to estimate in advance the impact on the time and cost of implementation. Only an experienced eye, will be able to advise you well to choose with which orientation to remodel your budget.
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