# How can I calculate the best sail size for the current wind?

Being a beginner in windsurf, I have several sails from 4.7 to 7.5 meters sq.

I find myself wondering how I can set the correct sail for the current wind.

How do we know what sail to use, and when to use it?

Is there any rule of thumb?

I came across a windsurfing blog post with a link to an Excel spreadsheet (titled "Ultimate Windsurfing Equipment Size Calculator"), developed by James Douglass. His spreadsheet runs some calculations using several factors:

• windsurfer's weight
• sail size

Boards:

• Minimum size beginners board you should be using
• Ideal first short board
• Smallest size windsurf board that can be uphauled

Sails:

• Two lists showing different wind strengths & what size sail you should be using
• A separate list showing wind strength & sail size for a beginner
• A graph showing ideal sail size versus wind speed

This spreadsheet might offer the type of info you're looking for. Mr. Douglass also provides an online version of his spreadsheet.

He also provides the following advice to beginners in this "Top 16 Windsurfing Questions Answered" FAQ:

Question #6- I’m a beginner windsurfer looking for my first sail. What kind of sail should I get, and in what size?

Answer You should get a sail between 2 and 7 meters squared, depending on your size and the wind speed you are likely to sail in most often. Check the windsurfing equipment calculator to see what’s right for you (pink line on chart). As you get better, you can start using sails closer in size to those recommended for experienced sailors (blue line on chart). Your first sail should have a minimum of 3 and a maximum of 6 battens, and should have no camber inducers or “cams” on any of the battens. Also, avoid sails and masts made before the year 2000 and sails advertised for racing.

Another site had some pointers regarding sail size:

For an amateur windsurfer, sails ranging from 5 to 6.5 square meters in size are recommended as they work well for light winds up to winds of 4-5 knots.

This article offers a quick overview of sails, with this final recommendation:

We suggest you start off by choosing light-wind sails to get the knack of windsurfing. Eventually, you can experiment with various sizes of the sails, and finally find the one that appeals to you the most.

Enjoy!

EDIT: Added info from James Douglass' FAQ and a link to an online version of his calculator.

In addition to JW01's post, a key step change in the sizes you should use comes at the point you progress past uphauling to water starts.

When you uphaul, a large sail can be incredibly difficult, as the wind tries to push it back down into the water, and if you can't uphaul rapidly you will tend to pivot round leaving the mast pointing upwind - so a smaller sail is ideal.

Once you can water start, a bigger sail actually makes life much easier, as all you have to do is lie in the water upwind of the board, with the mast on your shoulder (very easy) and pop it up to catch the wind. A nice big sail can then lift you onto the board in even relatively light winds.

Of course the other aspect not mentioned is sea and wind conditions - if the sea is choppy, a smaller sail can be much easier to manage, but if the wind is gusty a large sail can help ride through the lulls.

Unfortunately there is no simple answer because so many factors influence what is the right sail size (roughly in order of importance for beginners):

1. What you aim to do. Do you want to be planing? Do you want to do lightwind freestlye tricks? Do you want to improve sail handling? Do you want to learn to use a harness?
4. Wind strength
5. Board size and board type
6. Sail type (Slalom, Wave, Freestyle, Foil, etc.)
7. Fin size
8. Stability / Gustiness of the wind
9. Wave size

Depending on what you want to do, in the same 9-10m/s wind a very experienced windsurfer weighing 75kg could have a:

• 6.8m2 slalom sail and a 110L slalom board for blasting around.
• 5.6m2 freestyle sail and 95L freestyle board for doing freestyle tricks.
• 5.3m2 wave sail and 90L wave board for riding waves.
• 3.3m2 wave sail and 220L board if practicing something new that improves sail handling technique (e.g. heli-tack, backwinded sailing, reversing, board-sail 360)

The practical advice for beginners who don't really care about progress and just want to enjoy:

You will eventually get to know your gear and what sail is good for points 1-9. Just get on the water, start with bigger boards (160 - 250L, keel preferred) and smaller sails (3m2 - 5m2) (start with 3m2 if you weight 60kg or less, 5m2 if you weight 100kg) and you can slowly increase the sail size according to your comfort level.

The practical advice for beginners if you want to progress fast:

Take the biggest board you can find (220L+) and smallest sail you can find (3m2 - 5m2) (start with 3m2 if you weight 60kg or less, 5m2 if you weight 100kg) and practice these super-fun tricks and techniques:

• Tacks
• Fast tacks (can you get to the other side in four steps, three steps, two??)
• Gybes by flipping the sail first then the legs
• Gybes by flipping the legs first then the sail
• Sailing in switch stance
• Heli-tacks
• Board-sail 360's
• Backwinded sailing
• Reversing
• And the ten or so other "light-wind" techniques (you can do these in moderately strong wind (7-9ms) too, just make sure you have a 3m2 - 3.5m2 sail in these conditions if you weigh 75kg).

When you learn to do each one it is so rewarding and fun you want to do them all the time!!!!!

Why am I giving this advice?

Decide: Do you want progress (might look sill short term, but gives amazing results in long term) or try to look pro right away (also looks silly in short term because you don't have the skill, no learning, no results in the long term)?

From having taught over 500 people to windsurf I can say most people try to progress way too fast (we live in the era of instant gratification). Windsurfing is about enjoying the journey and the daily practice, being on the water and in nature. Many times I have had a student weighing 80kg with a 100L board and 6.6m2 sail come to a course to learn gybes. They barely stay upright with that gear, even just trying to sail in a straight line. I put them on a 220L board and 4.5m2 sail and then they are in the sweet spot for learning: they are falling down 30% of the time during training the gybes but make 70% of them: enough that we can see what is going wrong and start improving. If you are falling in over 50% of the time you are slowing your progress. We make the board as stable as possible because windsurfing is all about sail technique. If most of your focus is going into the board something is terribly wrong. In fact, if you want to progress even faster, the best thing you can do is practice on land because that is the most stable surface you can ever get, allowing you to focus on sail technique completely.

As an example, while being a windsurf instructor (3 years on the water pretty much every day) I found I could progress my own skill level fastest with a 220L board and 4.0m2 sail in wind speed of 1-7m/s, I weigh 75kg. It felt so strange when people with a few months of experience (on the water only weekends) would come with 6-7m2+ sail size and 100L boards to attend my gybe courses. The difference in what I was doing to maximize progress and what they were doing to try and look pro couldn't be more dramatic.

• There's a lot of commentary here that seems more targeted at general advice for a novice windsurfer than about choosing an appropriate sail size. I'm wondering if you can reduce the added commentary to just that which directly address the query.
– Nij
Jan 24 at 6:24
• Asking what is the appropriate sail size is like asking what are appropriate shoes for sports. The question is extremely general, hence the general answer. Feb 9 at 12:27
• Answering generally on how to choose a sail size is fine, because that is the question. Generally discussion of teaching and learning however is not answering the question. We aim to establish Q&A that do exactly that, unlike discussion forums or messageboards.
– Nij
Feb 9 at 19:18