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Of course it’s personal.

There is no definitive ‘engine’ or calculator or fixed spacing percentages rules. 

There are simply too many factors such as location, rider weight/body type, skill, discipline/preference, budget – and many more – to make a flow chart or easy-to-follow process. You are different to the next gal or guy on the beach, so your quiver will vary from theirs too. But here we’ll try to outline the main things to bear in mind.


  • Keep it simple
  • Invest the most in the core size/s you will use the most in the widest, most common wind band at your regular spot
  • Stick to one or as few brands as possible (E.g., Brand X in high wind, Brand Y in light wind.)
  • Demand wind range from sails for the best value, usability and least hassle/most fun
  • Optimize what fits the least masts and booms
  • Match rigs and boards smartly – avoid significantly over or under powering boards
  • Smaller size gaps in smaller sails, larger gaps in larger sails

First, let’s make a couple of assumptions:

We’re going to ignore wind under 13 knots, since that’s a specialist area requiring any number of approaches from WindSup, to longboarding, to Formula, foiling etc. We’re not going to address high-skills and/or extremes of bodyweight.

So no light-weight ‘easily planing’ freestylers in 14 knots, no racers riding 7.8s overpowered in 30 knots, speed freaks ‘overloading’ needles in strong wind with grunty sails etc. We’re talking recreational, realistic conditions across coastal and fresh-water spots for freeriding amateur wave sailors and regular blasters.

We’re going to assume a minimalist approach, because this will illustrate the value and importance of wind range in your chosen material. Wind range means less messing around and more time and fun on the water.

More things to bear in mind:

What have you already got? Are you building the quiver around some existing core items or starting out from scratch? This is important because, if some of that gear is ‘dated’, you can run into trouble. For example, efficient, modern board shapes need less power from the rig, but older boards will demand greater drive to get them up-and-running.

‘Modern’, say mid 00s onwards, boards and sails will have huge variances in behavior from earlier models despite the sizes of area, volume etc. being similar at their quoted level. That ‘type of drive’ is also important when you assess how much you will or will not mix brands, because, sticking with one brand (regardless of the extra advantages of sharing masts and ‘natural steps’ in sizing), also keeps the sensation and style of power delivery consistent as well.

One brand’s 4.7 can have as much power as another’s 5.3. That’s not a criticism of the ‘underpowered’ brand, but just an aspect of the different depth of profile used by one, whereas the other might have sails suited for ‘neutral’ feel with on/off power delivery for manoeuvres. So, largely stick to one brand and/or model within the range.)

Regardless of brands, luckily these days sail brands have really optimized how many sails their masts will fit. E.g., 400 masts will fit most sails from 5.5 down to 4.0. Even on an unlimited budget, it pays to ‘stretch’ the range of your quiver as much as possible – just to cope with the natural fluctuations in wind state and so on while you’re on the water.

This avoids time spent swapping material. Even if you had 3 sets on the beach, your time is best spent having fun on the water than scratching your chin over 0.3 sqm. of difference in sail size.

So buy sails with wind range and spend more on them  – especially the ones you will use the most – and the [lighter, stronger and better-performing] masts and booms they need and put anything extra over into boards and fins.

‘Spend for the conditions you get – not the conditions you want!’

Has Monty got the Sail for You?

Percentages Game – How to Pick Size Gaps

The difference between a 4.0 and 4.5 is most definitely not the same as between a 7.5 and an 8.0, despite there being the same variance in square meterage.

There is an interesting overlap around the top end of a F4 and bottom end of a F5 mark. (17 knots.) Here you will see wavesailors and freestylers happily planing on sails between 4.7 and 5.5 – but slalom and even freeriders riders very comfortable on 8.3s too.

Generally there’s a margin at around this wind speed and, say, sail size 5.5 where the size gaps change. This is because each Beaufort force of wind equals a doubling of air pressure on the sail. So up to F4 that doubling effect has been less significant. But from here on it starts to ramp up considerably.

This has a massive effect on what sail you can comfortably, effectively use at various times above and below that level. As a general rule you can go 0.5 increments from 5.5 down, maybe larger gaps if you are heavier.

Above this, the gaps can be significantly larger. In fact, you can probably jump from 7.8 to that 5.5 straightaway.

Matching boards
(We won’t even go into fins  – that’s another story!)

Bigger boards can get going sooner with smaller sails. Hence the trend of wave specialists using floatier boards and smaller rigs from ‘float and ride’ conditions (smaller lighter, more throwabout rig) and planing earlier thanks to the shorter, lighter mast and less cloth powering a corky board (now as turnable as older, smaller shapes were) more efficiently onto the plane in marginal conditions.

Smaller boards can absorb the wind pressure from bigger sails. (Think of speed needles with 5.8s in 40+ knots for example.) Also, the shorter, slimmer-railed and wider profiles of modern boards cope with the top end of the wind range and rougher water states much better than older boards, all while providing lower-end advantages too by feeling more stable and drivey thanks to the width, but are more manageable in hectic water due to the shorter nose and thinner sides.

So an 85-kg. rider on an 85-liter Freestyle-Wave board can now pretty much use that in up to the maximum sailable wind, probably 40 knots quite easily, whereas in the past they might have had to have a smaller board for high-wind days.

Similarly, that 85 might be fine around the low end of the wind band, at say 17 knots. Same for lighter winds, Modern freeride boards can be 80-cm. wide, but only 120 liters and 240-cm. long, planing as early as 140-liter versions of the past.

Pairing becomes even more critical in lower wind strengths. You may think it’s best to buy the biggest-possible sail for your light-wind board. But you have to be smart. Using smaller, lighter masts on a slightly smaller sail might be wiser than a larger mast for these bigger and heavier sails – think 460 and up to 7.8 might be best as a rotational versus a deep-bodied cambered sail, say an 8.0-m-plus cammed model that is significantly heavier and requires a 490 mast or more. (The 7.8 rotational might also fit on the same boom as your 5.5.)

Give big rotational sails a good amount of thought, because their elasticity and ‘early fill’ can often have you planing earlier than a high-skin-tension cammed foil. Cammed sails help absorb gusts and glide through lulls.

Ask yourself which do you need more? To be up and planing – or to stay planing in patchy wind?  Away from Formula boards, you need about 13 knots to get a big board and sail onto the plane, but only 10 to keep it there.

Looking at the Beaufort Scale you can see that’s into the ‘half-the-air-pressure’ zone of the band below. So a coastal rider might like the rotational that releases their board earlier, to then enjoy a consistently moderate coastal breeze, while an inland sailor might prefer the security of glide though lulls and holes from obstructions such as trees, buildings and land with a cammed sail.

A twin cam or switchable 2/3-cam could be the compromise here for light feel and maneuverability and stability in less clean air. Racers only use powerful, deep-bodied cammed sails because they sail overpowered at the very top end of the wind range, deep downwind for short bursts.

They do not reach up and down across the wind for hours on end where a rotational can be just as fast, let alone much less energy-sapping. That said, cams cope with gusts and lulls better, it’s up to you! Everything is about comfort.

Don’t let ‘snobbery’ influence you into buying the race sail when the freeride might deliver more. The same in higher winds: Your local conditions might suit a freestyle-wave better than the shiny quad you want, regardless of your ability.

Invest in the sail and board you want to use most  – or rather, are likely to use most given the most common, regular conditions. Build around your ‘core sailing’ sizes and then extend above and below this.

Will that 18-knot-plus band be the most prevalent at your spot, or do you need to spend bigger in the sub 18-knot band? Maybe you’re not even interested unless it’s 18 knots. Do you need more boards and less sails?

Or the opposite, with floatier boards capable of carrying a wide range of rigs? To find the answer,remember, everything in [both life and] windsurfing is an efficiency contest! What can produce the most [power, speed, dynamism – fun!] for the least [effort, weight, expense].

Competition sailors will agree. There’s no point having ‘specialist’ gear if it takes all their concentration to handle it, when their focus could be totally on what they need to do thanks to forgiving material in their hands.

Bear in mind brands and if you are a ‘loyal’ user and, assuming you use their branded mast, what this limits or does not limit you to in terms of compatible other sails you can buy to complement your hardware.

The hardest wind to plane is in sub-13-knot conditions. Do you need a planing board and sail combo for then? (Or will you longboard, foil, float and ride, WindSup, surf, go to the pub or ride a bike instead etc.?)

14-18 is generally float and ride waves, longboarding, light-wind freeride/slalom/Formula territory. Maybe a few light-weight freestylers can get up-and-running in this kind of wind too. (Give or take some strong currents, gust, obstructed air and so on.)

18-knots-plus is where everyone can plane in all disciplines and sea states


If you only want to sail in 18+ knots: You can have as little as one board and two or three sails.

1 Board from your weight in kg. in liters +5/10 (to account for some neoprene weight dependent on season).

  • 95-liter Wave/FSW for an average-weight windsurfer of 85 kg.

Sails in 0.5-m. increments for the average rider (and up to 0.7-sqm. increments for larger riders) for freeride/wave crossover sails under 6.0.

  • 5.3 for 18-24 knots
  • 4.8 for 24-30 knots
  • 4.2 for strong-wind days

For a rider sailing 13-40 knots: You can do this on 2 boards and only one extra sail. (Again, 85-kg.-rider example.)

  • 120-liter x 80-wide freeride/freeerace/slalom board
  • 95-liter Wave/FSW
  • 7.8 rotational or twin cam
  • 3 x Wave or FSW and wave/crossover sails as above in the 18+ example

There are ways of going even more minimalist, but you get the picture … save the rest for a nice trip away, or a better wetsuit to extend your season, a long-lasting carbon boom, some coaching to get to the next level, good fins, a more responsive mast …

Good winds!