Have you ever dismasted and then re-raised? Or, have you ever noticed that you have a soft rigging? Have you ever had the need to measure the rigging tension of your sailboat?
Well, to do that there is an instrument called a StringMeter for shrouds. It is used to measure the tension of the shrouds correctly, for navigation or before a race. It is mainly used on racing boats in fact, on boats where there are the turnbuckles and the backstay, as on some cruise boats where they are more easily adjustable.
Today we have lined a J / 27 with which tomorrow we will make a regatta inter circles here in Genoa. So we had to fine-tune the rigging once the tree was installed. First you have to make sure that the hammers, if any, of the shrouds are inserted well in the tree and that it is all in order on the crosses and in the head of the tree, in case fix the hammers and the end of the turnbuckles. Replace new ones with old ones, oxidized or rusty and simply too old or deformed. The rigging must also pay special attention, it is a good idea to change it at least after thirty years, but it is certainly worth doing before. But now we come to us: to measure the tension, first take the diameter of the steel cable to be measured and then know which scale it corresponds to. Then take the steel shroud or the steel cable and insert it into the recess at the bottom of the instrument. Pull the cord with your finger and tension the instrument and read the mine in the middle of the steel cable. At that point, take the reference between the two values of the scale. For example, in our case the value is 12.5, mark it in mind and then remove the StringMeter from the shroud.
Take the reference value, in this case on the first scale, that from 3/16 take the two reference values 240 for 10 and 320 for 15 and making a quick calculation, it turns out that the value 12.5 turns out to be 280, so a tension of 280 sheets. The same tension must also be read on the other shroud, if it is not so it is to be regulated at the same tension. I remind you that the shrouds should not be pulled completely, you must follow the manual of your boat or, in the manual of the StringMeter follow the instructions for the breaking load of your stay or rigging. The shroud under wind must be less tense than that above the wind of course.
The instrument reference site is www.loosnaples.com