Choosing the ideal mast is not an easy thing. Everyone who has ever tried to rig a pryde sail on a gaastra mast knows that. In fact, many factors have an impact on the sail profile and performance. The windsurf mats length, the stiffness, the bend characteristics the carbon percentage, the diametre and more. Windsurfers who want to achieve a maximum of performance should stick tot the officially recommended surf mast offered by the sail manufacturer. But in general, these original masts are pretty expensive compared to a similar third-party-mast from a windsurf material supplier. Often, you can pick a third-party mast almost without any performance loss and in most cases, this can save you a considerable amount of money that you can invest in other equipment. Let us quickly explain what you need to respect when browsing for a mast that is not the original one offered by your sail brand...See our windsurf masts here: SDM Masts (Standard Diametre), RDM Mast (Reduced Diametre), STX RDM Masts, Hardtop Masts, Flextop Masts
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Mast manufacturers state their mast stiffnesses in IMCS, an indicator that you can calculate with the help of a complicated mathematical term. The higher the value, the stiffer the mast. For example, a 340 cm mast has a stiffness of 15 IMCS, a 430 mast 21 IMCS and a 460 mast 25 IMCS. This is due to the fact that the stiffnesses are standardized nowadays, so that when choosing the mast length, you have also already chosen the stiffness. This is comfortable for you - one property less that you have to take care of.
The ideal length is printed on the sail in most cases. It is hidden in a value called "Luff". You have the perfect mast if you reach exactly the luff when adding the mast length to your mast extension length. An example: For Luff 453 cm, you should use a 430 cm mast with a 23 cm mast extension. Some sails are equipped with a vario top which means that you can adust the mast top and let the mast tip emerge from the sail top. Regarding the bend caracteristics of the mast, this is not always a perfect solution but can help to reduce the quantity of masts needed to rig all your sails.
You cannot simply reduce the question about the mast stiffness to the IMCS indicator. It is true that this indicator says something about the total deflectoin all over the mast length, but it says nothing on how much deflection you have on the base and on the top. This is what you need the bend characteristics for. The deflection ratio for top and base can be used to distinguish three categories of bend characteristics: You have constant curve (also CC) with a "regular" deflection, Flex Top (or FT or progressive flex) where the top part has a higher deflection than usual, and hard top (HT) where the mast top flexes less. Given the fact that the mast sleeves of windsurf sails differ regarding the deflection, it is clear that a sail only twists perfectly if the bend curve of the mast corresponds to the sail cut. Only this way, the sail has a fixed pressure point, the desired profile, a good drag and can still be controlled in overpower. We will be happy to give advice regarding your mast choice.
This is a question that you have to reply yourself. I can tell that it is not as easy as it looks at first glance.
Advantages of more carbon:
On the one hand, a higher carbon content means a better reflex and a better sail performance: Almost without a lag, the mast flex adapts to the optimal wind conditions. So the sail remains controlable and optimizes the planining through wind holes. Another point for a higher carbon content is the reduced weight although the weight saving is not very striking.
Advantages of less carbon:
The higher the carbon percentage, the higher the risk of air bubbles in the carbon mesh. A special construction called PrePreg, where the carbon layers are impregnated with resin, reduces this risk, but it is still possible. These air bubbles are predeterminated breaking points. Therefore, a material failure gets more probable with a high carbon content. Another disadvantage is the exponentially increasing price that you have to pay for a higher carbon content. These considerations lead us to our recommendation for advanced leisure windsurfers to choose a carbon content between 60 and 80 % while beginners should stick to 30 to 50 % carbon.
It is a a custom to use rdm masts (also called skinny masts) in smaller sails. This is why many brands only offer rdm masts up to 430 cm or 460 cm max. RDM masts are heavier than SDM masts although the diametre is reduced. The reason is the higher wall thickness that you need to meet the stability requirements. The reduced diameter also promotes a better sail profile, a better shift and a better handling. Also, it is said that rdm masts crack less often. Another advantage of skinny masts gets obvious while rigging the sail: You can push the mast in more easily.
Polyamide cover: This considerably increases the scratch resistance
Alutex cover: increases the UV ray resistance
Kevlar inlay: Increases the scratch resistance in the boom area
Mastbag: Protects your mast against scratches, bumps and UV rays
Prepreg construktion: Preimpregnated carbon fibers guarantee a more regular dispersal of carbon fibers and epoxy resin which reduces the risk of air bubbles.