How to TuneAuthor??? gives the beginner an introduction to tuning, in a simple step-by-step process - Summer 2004
Getting your head round tuning your dinghy can seem impossible if you're a beginner - particularly if you don't understand the lingo or know your spreaders from your shrouds. We guide you though the basic process of tweaking...|
Articles on boat tuning tend to assume you already have a certain level of knowledge - but that's no help if you've never done it before. So in this article we will strip away the jargon and give you a simple step-by-step guide on tuning your dinghy, so by the end you'll understand how to set up your boat with a basic rig configuration. It is about 'how' and not 'why' - think of it as tuning by numbers.
We want to start by exploding two commonly held myths. First is that the only reason to tune your boat is to make it go faster. While it's true that tuning your boat will make you go faster, a properly tuned boat will also be better balanced, more forgiving in the gusts generally easier and more pleasurable to sail, particularly in stronger winds. Go to any sailing club on a moderately windy afternoon and you will see many sailors struggling to stay in control of their boats, more often than not, a badly tuned boat is the main reason for this, not poor sailing skills.
Myth two is that tuning is a complicated and intuitive process. The best kept secret about tuning is that there is no secret. Strip away the jargon and it is simply the application of some standard measurements to the rig and it's position in the boat.
At it's simplest level, tuning is setting a rig up to the optimum combination of three measurements:
This is the first part of the tuning process, which roughly sets up the rig in the boat.
Having got the rig roughly set up, we now need to ensure that it is set up symmetrically in the boat. So, first pull the rig tension back onto your approximate mark on the for deck post. Next tie one of your pieces of rope across the shroud plates - when doing this, make sure it is taut and not being pulled out of it's natural lie by the boom.
Now turn the boat on it's side (tie in your boom or better still remove it).
Check that the spreaders are at an equal height on the shrouds. Cleat the main halyard and pull it taut down to one spreader end. Grip the halyard tight between the thumb and forefinger at this position and arc it across to the other shroud. This will show you if your spreader heights are different. Move one or both spreader ends up or down the shrouds until they are at equal heights.
Tie the other piece of rope across the spreaders. We now want to ensure that both spreaders are at equal angles. To do this, look down the mast from the mast tip to see how the rope across the shroud base lines up against the rope across the spreaders. If the spreaders are at equal angles the ropes will be parallel to each other. If they are not parallel one spreader will need to be angled further back using the adjustment system at the spreader bracket until the ropes are parallel.
To decide which spreader to move and in which direction, first measure the pre-bend. This is done by pulling the main halyard to the gooseneck and pulling it tight and then measuring the distance from the halyard to the rear of the mast at spreader bracket level. If the tuning guide specifies that you should be measuring deflection, you can measure out to the rope tied across the spreaders. If the measurement you have is less than the measurement in the tuning guide you will need to move the spreader that is angled further forward back and vice versa. To adjust the spreaders you might need to ease the rig tension but remember to pull it back on again before you re-sight down the mast.
Now check that the mast is in the column - i.e. it is not bending off to one side. To do this put the boat upright on it's trolley again and sight up the mast track. If it does not bend off to one side, great. If it does, we need to correct this. This can be done by lowering or raising the shroud on one side.
To fine tune the rig all you do is make small incremental adjustments to rake and spreader angles until, at the prescribed rig tension, you have the right rake and pre bend measurements.
First pull on the rig tension until you get the correct rig tension. Then measure both rake and pre bend. Once you have measured these, consider what you need to adjust in terms of spreader angle and shroud adjustment to get the desired pre bend and rake. Unfortunately, as you change one variable you also change the other.
Finally mark everything off with a marker pen so that you can replicate those magic settings you've worked so hard to find: mark off the rig tension position on the mast, mark off the shroud tension on the mast step post and similarly for the lowers.
The above is a very quick guide to tuning but for a more detailed account refer to Mike Calvert's previous article on this subject.
Setting up the mast - Graham Williamson
Calibrating the Rig - Graham Williamson