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Boat Tuning – Know your Numbers!

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In boat tuning in general you can differentiate between static and dynamic settings. Static settings usually cannot be changed on the water or are not allowed to be changed during a race (i.e. spreader angle, shroud tension in many classes,…) whereas dynamic settings are those you permanently Change even during a race (cunningham, vang tensions, centreboard,…).

Static Settings

You usually start with setting up the static settings before you go out on the water. Setting up the boat right can be an art. There are actually only two options for approaching this matter:

  • Do a rough setup and that’s it: This can already take the boat up to 90% of its possible performance, maybe even more. I know a few top sailors who do their boat tuning by feel and only approximate settings.
  • Be nerdy with your settings: Some (myself included) write even down the outside temperature when they measure the tension of the shrouds.

There is no way between these two. Either you are very accurate or not at all. Anything between doesn’t really help because measurements need to be accurate as minor changes might have a big effect on the boat’s performance. For example if you change the prebend by 5mm the depth in the sail varies by a few centimeters.

No matter what class of boat you are sailing you should consider the following points:

  • First check if the shrouds, spreaders etc. all have equal lengths. If the one shroud is 3mm longer than the other one the numbers on each side might be different.
  • Check if the spreaders are fitted centrical (Believe me there are always more suprises as you may think when people start checking if the fittings are properly mounted to the mast…).
  • Check if the shrouds are parallel when you look at your boat from the side. If not one spreader needs to be adjusted further to front or back.
  • Where is the prebend measured? At the spreaders? If you compare different masts do the spreaders have the same height?
  • When measuring prebend / masts where is the rope tied to (i.e. on mast track)?
  • Rig tension always needs to be measured on both sides – starboard and port. Always at the same point. Check the outside temperature as well. There are differences between summer and winter temperatures.
  • The rake is also dependant on the shape of the boat – flat transom
  • When you want to measure masts from different manufacturers check if there is a standard method for measurement. If yes try to use it as it will be much easier to compare data with others.
  • If your boat is very soft the rig tension might be different before and after sailing.
  • Define how you measure your boat when you compare with others. Otherwise you compare apples and oranges.


On the water – Dynamic settings

After you have tuned your boat into static settings it is time to go on the water and find the right adjustment for the dynamic settings.

The best way to work on boat speed is the classical two-boat-testing.

Two boats line up next to each other and sail in one direction to see which boat is faster. It is very important that the one boat doesn’t sail in the disturbed wind of the other one. As soon as this happens you better stop and line up again.

Between the boats there should be a gap of at least two boat lengh depending on the wind strength.



After the slower boat has fallen out to the back both boats stop and the slower boat does some changes to the setup.

Change windward / leeward position to make sure it is not just the wind which always favours the windward boat or the other way round.



Environment for successfull two-boat-tuning:

  • You only can do proper two-boat-testing on open water with stable winds – otherwise you can never be sure if the one boat was really faster or if it was just the wind; the best test conditions are on open water with the wind blowing onshore.
  • The two boats should never change settings at the same time. You always need one absolute term to know if the changes helped or not or maybe even made it worse.
  • Before you hit the water talk through the changes you want to try out and about the results you hope for. The more specific you are the better the results will be.
  • Be open and talk about everything with your training partner. Do not hide anything. Only if both training partners are open and share what they learn the improvement process is at its best. Always bear in mind that you do not want to beat your training partner but you two want to beat all the others when it comes to major competitions. What is better? Finishing 25th at an event and beating your training partner or finishing 2nd just behind him…

What can I do if I do not have a training partner?

It is harder and also takes longer to achieve good results but it is not impossible. You can either buy some good tools that show your VMG and target speed (even in small dinghies). I have even met sailors who train a lot at their own and improve their boat speed just by feel. Therefore you already need to have a really good feel for boats and how they are supposed to react to changes. But time on the water always helps to improve your boat speed and your boat tuning.





The best settings for cunningham, in-/outhaul, vang, centreboard etc. vary quite a bit between the different boat classes. Therefore you better look on the website of your class or ask your sailmaker how to do the basic setup. Normally there are always really good guides for the basics and as soon as it goes into fine boat tuning you need to spend quite some hours on the water – if possible together with a good training partner. Just make sure to document every change and to write down which settings are good in which conditions. This way you will build up quite a comprehensive personal tuning guide and when you haven’t sailed in certain conditions for quite a while it will be much easier to find your fast settings again.

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