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  3. Extensions

Extensions

Extension is another piece of surfing equipment without which we cannot imagine windsurfing. There are a huge variety of extensions on the market that vary in thickness, length, materials and mounting system. And of course, the differences are obvious in the prices. What is the right extension for you?
 
The two most important features that determine what kind of extension we need are the thickness and length of the extension, which depend on the sail and mast used for the selected sail. For the smaller sized sails (up to approx. 5 m2), almost only the RDM (skinny) mast is used today, which means that if you use an extension in combination with the RDM mast, you also need an RDM (skinny) extension. SDM masts that have a standard diameter also need an SDM (standard) extension. The RDM (skinny) extension has a pipe diameter of 32 mm and the SDM (standard) extension has a pipe diameter of 48 mm.

                                                                                                                       
                                                                          RDM (skinny) extension                                                        SDM (standard) extension


The length of the extension itself depends on how much mast length are we missing if we subtract from each other the required length of the sail along the mast and the length of the mast. The difference is the length that we have to make up for with the extension so that the sail can be properly assembled. On the sail you also have written the required length of the mast (eg 448 cm), which means that you need a mast length of 430 cm and an extension length over 18 cm. On some sails you even have written what is the recommended length of the mast and extension (430 + 18 cm). Especially with wave and freestyle sails that have a vario top you can, of course, use longer masts than are suggested for the sail. However, it is important to adjust the height properly with a vario top so that the bottom edge of the sail is as close as possible to the bottom edge of the extension or the base.
 
Extensions are made in different lengths. The most common lengths are 15 cm, 30 cm and 45 cm. For the most optimally adjusted sail, it is recommended that the mast and extension lengths comply with the sail manufacturer's instructions. Oz. in other words, use the mast length recommended by the sail manufacturer and replace the required difference with a suitable extension.
 
Now that we know the width and length of the extension we need; the next important feature is the extension lockout system itself. If the extension and mast base or joint are not compatible with each other, you will not be able to attach the sails to the board, which means that you will be watching the others from the land.
 
The most common baseplate and extension system is the "U-pin" system, but there is also a "double pin (US pin)" system. A baseplate with a U-pin system is one that has a metal pin, about 7 cm long and 1 cm in diameter, with one or two notches. For the U-pin joint system, you need an extension that has in the centre a hole with a slightly larger diameter than the metal pin on the joint is (approximately 1 cm). Inside the extension there is a pin that locks into the notch on the joint.

                                                                             
                                                                     U-pin baseplate                                                       Extension with U-pin mounting system
 
The "double pin (US pin)" system has two pins on each side of the hinge, which locks into the side holes at the extension. You've definitely seen this system before, but it's less widespread than the U-pin system.
 
                                                                                 
                                                                             
                                                           Double pin (US pin) baseplate                                                   Extension with double pin (US pin) mounting system

You now have all of the important attributes listed that you need to buy the right extension. The last feature is the material from which the extension is made. Most widely used are aluminium extensions.
 
In recent years, carbon extensions have been entering the market with lightning speed. In terms of durability and reliability, carbon extensions are equivalent to those of aluminium. The biggest advantage of carbon extensions is the weight, since a carbon extension 45 cm long is over than 40% (approx. 400 grams) lighter than aluminium one of the same length. The disadvantage of carbon extensions is the price. For the price of one carbon extension you currently get two aluminium extensions. For those who want to reach the limits with equipment and where every gram is important to you, we recommend using carbon extensions. Most average and advanced users, however, are completely satisfied with the aluminium extensions.

                                         
                                       Aluminium extension body                                                                                                            Carbon extension body
                  
 
For extensions, we recommend proper inspection, maintenance and replacement every few years (approx. 5-7 years if you take good care of them). Due to wear, we recommend changing the extension downhaul rope every 1 - 2 years (ie 30 - 50 surf days). Although the extensions are made of stainless material and very durable plastic, over time, some vital parts lose their strength. Micro-cracks can appear and the extension breaks.