WINDSURFING MASTS EXPLAINED - HOW TO CHOOSE THE BEST MAST FOR YOUR SAILS
PUT YOUR MONEY WHERE YOUR MAST IS
Buying a mast can be confusing. Here we aim to simplify things for you, give advice and outline the science behind mast bend curves, response and construction and guide you to selecting the right model for you – so you can then enjoy several seasons of performance and durability that will see your money well spent.
The first thing to stress in this vital decision for windsurfers is that if there’s one area you don’t want to scrimp and save on, it’s picking the right masts for your sails. (OK, fins are pretty vital too, as are boards and sails of course. But a badly matched mast and poorly selected fins will ruin your day - no matter what rig and board they’re paired with.)
CHECK OUT THE MAST PRODUCTS PLAYLIST AT OUR YOUTUBE CHANNEL
BANG FOR BUCK
But, once you’ve spent your money you can relax knowing you’ve got the best tool for the job.
Trust us. Get it right first time and you’ll enjoy amazing, long-lasting value for money from your mast for several seasons and generally not have to worry about trading them in or up for the latest model each year.
Also, although we hope you enjoy reading this, we recommend you always go to your local dealer for extra advice and service. They’ve seen tonnes of sails and masts and can examine your quiver and guarantee you’ll leave with the right model for you.
LIKE FOR LIKE
An important aspect of optimum sail trim is the mast you choose - in combination with the correct down and outhaul.
In this respect it’s considered good practice to follow the mast type and length recommendation of the sail manufacturer.
These recommendations are based on an average weight of the rider. Sometimes more mast length options are provided or available.
So, first check the numbers (as explained below) on your current mast with what the sail you’re trying to match it with recommends.
Mostly, the sail manufacturer’s own mast will be the best pick as it was the one they developed it on.
But you may want to buy an independent brand (yes, such as Unifiber!), to feel sure you can match a wide range of sails in the future or that already exist in your quiver.
However, there are variances from mast to mast (and Unifiber masts also have some small variations too) so our masts – seen in our MAST SELECTOR – are based on the averages from all the masts from all the brands we’ve measured over the past seasons.
You can never record enough data, but we’ve measured a lot and we and our long-standing store customers are confident we’ve got a solid overview in our mast selector guide.
THREE EASY STEPS
The key elements to consider when choosing a mast are:
1. Bend Curve
3. Carbon Content
First, let’s look at Carbon Content.
HOW MUCH CARBON CONTENT IS BEST?
Normally the carbon contents of masts varies between 30% and 100%. The higher the carbon content the more responsive and crisp your rig will feel.
Also a higher content results in a lower weight with more control from the reduced inertia. The carbon percentage represents the carbon content aspect only as clearly not 100% of the mast can be made purely of carbon. (The epoxy resin and other materials are not taken into consideration.)
Lower carbon content, which also makes masts cheaper, results in heavier and less responsive, ‘deader-feeling’ masts.
Sails will always perform best on the higher percentage models, but for strength, especially in say, wavesailing, 80% can be a good mix of durability and performance.
Another issue to bear in mind for maximizing durability, especially in surf, is to consider sails with lower luff curve so the mast is under less tension to start with.
The Bend Curve represents the shape of your mast under load. As we normally use conical-shaped masts (wider at bottom than top) the mast top bends a lot more than the bottom under load.
So, the Bend Curve is the difference in bend between the top and bottom part of your mast.
The IMCS mast stiffness is related to how your mast bends under load. A lower stiffness results in a softer mast.
Normally the Bend Curve value is rated between 6 and 20.
20 for a very high bending (flexible) top and 6 for a very low bending (stiff) top.
Most mast manufacturers adhere to the more or less normalized mast length-related stiffness. E.g., 400 masts are often rated at 19 IMCS, 430s as 21, 460s as 25 and 490s at 29.
Hence longer masts are normally stiffer than a shorter mast. Unifiber also follows the above IMCS values per given mast length.
Flex top (also known as soft-top) masts are built differently to hard-top (stiff) masts and use a different orientation of composite fibers and diameter higher up.
This doesn’t make them weaker, as they have more flex and forgiveness under stress, so the durability aspect between hard and soft-top masts is negligible. (Soft-top masts will also therefore have a closer wall thickness to overall thickness ratio at the top section.)
RELATIONSHIP BETWEEN BEND CURVE AND STIFFNESS
Here are some of the main influences of different Bend Curves (flexier or harder tops) and mast IMCS stiffness (softer or stiffer masts) on sail behavior:
INFLUENCE OF MAST BEND CURVE ON SAIL BEHAVIOR
More Top Flex = Higher Bend Curve Figure
Centre of Effort moves downwards
Less Top Flex = Lower Bend Curve Figure
Centre of Effort moves higher
INFLUENCE OF MAST STIFFNESS ON SAIL BEHAVIOR
Mast Stiffness Higher than Specified By Manufacturer
More stable sail
Better for heavier riders
Good for flat water sailing
Mast Stiffness Lower than Specified By Manufacturer
Less stable sail
Better for lighter riders
Adds control and speed when sailing choppy water
From experience we also know that extending the base with 30 cm extra could have a positive effect on softness and control of the rig.
Changing the stiffness and or Bend Curve of your masts is possible in a number of ways. E.g., via cutting or extending the top of your mast – and/or doing the same for the bottom part.
Also now and then mixing bases and mast tops of different length masts is possible, often with considerable influence on both BC and IMCS. (Not necessarily possible on all brands – and not intentionally possible for Unifiber or recommended.)
Out of these possibilities we like to highlight a very practical one to soften your rig:
Extend the bottom part of a shorter mast with 30 cm extra. E.g., a 430+30 becomes a 460.
The effect will be a 460 mast with the stiffness of the 430 mast plus around one stiffness point. Also a very little bit of top flex will be added (around 0.5 point).
Understanding the above knowledge of your mast will help you to improve your sailing performance and fun on the water.
Not enough Science for you? Well read on and we’ll tell you how we test various sail brands’ masts with our own specially-built machine.
HOW BEND CURVE AND IMCS ARE CALCULATED
The Bend Curve (BC) and IMCS stiffness can be determined via the commonly used IMCS mast measurement method.
This is calculated by hanging a 30-kg. dead weight at the mast’s midpoint and measuring the mast deflection at 1/4, 1/2 and ¾ of the length.
Bend Curve can be determined by subtracting the deflection at the 3/4 and 1/4 points along the length (as a percentage of the mid deflection).
Stiffness will be determined via the mid point deflection.
Normally the Bend Curve value is between 6 and 20.
20 for a very high bending (flexible) top and 6 for a very low bending (stiff) top.
Many sail manufacturers use different Bend Curve figures, though. E.g., NeilPryde’s Bend Curve is traditionally in the flex top range. See also below the Unifiber mast selector for an overview of sail brands and their related mast type.
To enable a relative easy choice, mast types are categorized in Hard Top, Constant curve and Flex top.
WINDSURF MAST STIFFNESS MEASUREMENT
To give you a little more feel on mast stiffness figures, see below the calculation method and a few typical mid deflection figures (under 30 Kg load).
IMCS stiffness = ( Length X Length X Length ) : (460 X 460 X Mid deflection), under a load of 30 Kg. For the ‘Length’ we normally take fixed ruler length (e.g., 400, 430, 460 etc.). This to use the same measuring length for a given mast length.
If we take the more or less normalized IMCS range of 19 (400 mast), 21, 25 and 29 for a 490 mast, the actual mid deflection figures in mm. are around 159 mm. (400), 179 mm. (430), 184 mm. (460) and 192 mm. for a 490 mast. All when loaded with 30 Kg.
Adhering to this accepted measurement method enables easy transfer of results and comparisons with other tests. Our measurement set-up enables a measurement resolution of +/- 0,1 IMCS points and about +/- 0,25 Bend Curve points.
Absolute measurement accuracy is very hard to determine because no reference mast can be obtained. Just in case you are interested in details of above measuring method or building your own measuring set up, please contact Unifiber.
Unifiber started a few years ago to measure and collect mast data from practically all known mast / sail manufacturers.
To enable a reliable outcome we tried to measure a number of masts of the same type and length. This was to get some grip on variation in BC and stiffness.
We learned that production tolerances in stiffness and BC are seldom below 1 BC and or IMCS point.
Apart from these production tolerances we see an overall trend from hard top masts more towards constant curve masts for a few race sails.
The above mast selector is based on 2014 sails. Please contact Unifiber for older versions of the mast selector that we started in 2011.
Great masts are the backbone of our business.
We launched Unifiber 11 years ago with one goal: to establish a genuine rig component company where the mast is king. In order to achieve this we had to get the microscope out and research a hugely diverse number of masts, from every manufacturer, to correctly identify and quantify the bend characteristics required for our product range. We offer Choice, Performance, Compatibility, Durability, Value, regardless of carbon content.
11 years later we continue to be driven by the same goal and our mast range is the most comprehensive in the industry with 97 individual models across three bend curves (Hard Top, Constant Curve and Flex Top) to fit nearly 100% of sails out there, which must make us market leaders!
With all these masts it becomes really important to make selection of the right model a simple task. Our universal mast selector is continually updated and the perfect tool to make the choice effortless.
Every bend curve and reflex is covered, because your sail brand’s mast may not suit you, or be available, or in your budget. You deserve a choice!
We also give a comprehensive 1-yr warranty term on all models.
- All masts benefit from an updated finishing process. C40 and C60 masts have a matt black finish with spiral. The C80 and C100 masts have a white finish with alutex spiral.
- All C100 SDM masts feature an extra radial pressure layer, which enhances durability at the cost of just a few grams in weight.
- SDM C80 and SDM C100 masts have a slightly shaped taper design. Meaning they become thinner faster, increasing the breaking strength even further.
- RDM C40 Greatly improved responsiveness because of the upgraded construction layup. True carbon performance, (unlike your everyday 40% RDM bendy fishing rod). Even our low carbon content masts are made from the best Pre-preg materials.
Benefits of Unifiber Masts:
Super Value for Money
Long Life Durability
Consistent Quality through Pre-Preg manufacturing methods