In this article:
Mast length:
Poles are offered in 30-centimetre increments from 340 to 520 centimetres in length. The example photo above with the indication "430" therefore shows a mast with a length of 430 cm. The required length depends on the size of the sail - a small 3.7 square metre sail often manages with a 340 cm mast, whereas a 9.5 cm light wind sail needs the longest version. The differences between the length of the mast and the dimensions required for the respective sail are equalised by using a mast extension or a vario top.
Sometimes two different mast lengths can be considered for one and the same sail. An example: A 5.3 sail with a Vario top and a specified luff length of 420 cm could either be ridden on a 400 cm mast with a 20 cm extension, or a 430 cm mast could be extended by ten centimetres on the Vario top. The following applies: Longer masts are always harder. The harder the mast, the tighter the sail feels. This can be an advantage for heavy riders (> 95 kilos), but in the hands of very light surfers (< 65 kilos), the hard mast often means that the necessary profile is no longer pulled into the sail - a shorter mast would be more suitable in this case.
RDM & SDM:
Two basic mast diameters have become established on the market across all brands and models. Standard diameter masts (SDM = Standard Diameter Mast) are now only used in large sails over 6.5 square metres and in regattas. Due to their larger diameter, they are somewhat stiffer on average, which is particularly advantageous in the high-performance sector, for example in slalom and racing sails for competitions.
Today, sails for hobby surfers, but also for competition disciplines such as freestyle and wave riding, are almost exclusively rigged on thinner masts, which are known as "RDM" or "skinnys" (RDM = reduced diameter mast). RDM masts make gripping the mast much easier and are also more stable against breaking loads due to their thicker wall thickness.
Carbon content:
The carbon content is printed on every mast, usually with information such as C30, C60, C80, C100 - the number indicates the carbon content as a percentage, the rest is usually made of glass fibre, resin is always necessary. The higher the carbon content, the higher the quality but also the more expensive the mast. In practice, the difference is noticeable in terms of weight - masts with a high carbon content are lighter - and also in the "recovery speed": while masts with a low carbon content swing quite slowly when surfing in choppy water, high-quality carbon masts return to their ideal position more quickly, making the sail feel lighter, more reactive and easier to handle.
Tip: An inexpensive mast with 30-50 per cent carbon is always sufficient for beginners and first attempts at gliding. Ambitious hobby surfers get a high-performance and, above all, affordable product in the 50-80 per cent carbon class; the reduction in performance and handling is hardly noticeable compared to the premium masts with 100 per cent carbon. So who needs full carbon masts anyway? Regatta professionals and anyone who simply wants the best and lightest and has the necessary change in their pocket.
IMCS value:
The IMCS value (IMCS = Indexed Mast Check System) is a relic from the past and is very limited in its informative value, but it is still stubbornly printed on every mast. It indicates the mast hardness - the lower the value, the softer the mast. However, as there are no differences in hardness within one and the same mast length anyway - for example, all 400 masts have a hardness of 19, all 430 masts a hardness of 21, etc. - you should not be confused by this. So if you buy the right mast length for your sail, you will automatically always have the right mast hardness.
Bending curve:
In the past, many sail manufacturers cooked their own soup and designed masts that fitted their own sails exactly. There were masts that were softer in the upper area and could therefore bend more there (flex top) and those with relatively less bend in the top area (hard top). If you simply combined sails and masts of different brands in a wild way, you could be out of luck - if the bending curve did not match the sail. In the worst case scenario, the consequences on the water ranged from poor control and limited batten rotation to reduced planing performance. Fortunately, in recent years more and more brands have switched to the "constant curve" golden mean, which fits almost all brands and models quite well. So if you want or need to combine sails and masts from different brands, you have the lowest risk of error with a mast labelled "Constant Curve".
surf tip: In the "Mast-Selector" from manufacturer Unifiber you can see exactly which masts fit which sails
