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Windsurf UJs & Mast Extensions

Adjusting your downhaul on your windsurfer or getting the foot close to the deck. You need a good mast extension to get the correct height for your sail. Maybe a rachet Duotone mast extension is a good plan to make life easy.
  • Chinook Ali Extension SDM 28cm Windsurfing Alloy

    Original price £85.95 - Original price £85.95
    Original price
    £85.95
    £85.95 - £85.95
    Current price £85.95

    Chinook windsurfing equipment is widely regarded as the toughest hardcore kit anywhere in the world. Their unconditional warranty means you can tre...

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    Original price £85.95 - Original price £85.95
    Original price
    £85.95
    £85.95 - £85.95
    Current price £85.95
  • Chinook Ali Extension SDM 48cm Windsurfing

    Original price £99.95 - Original price £99.95
    Original price
    £99.95
    £99.95 - £99.95
    Current price £99.95

    Chinook windsurfing equipment is widely regarded as the toughest hardcore kit anywhere in the world. Their unconditional warranty means you can tre...

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    Original price £99.95 - Original price £99.95
    Original price
    £99.95
    £99.95 - £99.95
    Current price £99.95
  • Chinook Carbon 48cm SDM

    Original price £155.00 - Original price £155.00
    Original price
    £155.00
    £155.00 - £155.00
    Current price £155.00

    Chinook Carbon 48cm SDM Standerd Diameter Chinook's Carbon Base Extensions feature the Power Haul Cleat and pulley, and a ring-and-groove adjustmen...

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    Original price £155.00 - Original price £155.00
    Original price
    £155.00
    £155.00 - £155.00
    Current price £155.00
    Sold out
  • Chinook Carbon RDM 32cm windsurfing mast extension Euro pin

    Original price £145.00 - Original price £145.00
    Original price
    £145.00
    £145.00 - £145.00
    Current price £145.00

    Probably the most highly regarded extensions on the market. New extended length! Ultra light weight Elegant and very strong New easy to use Compos...

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    Original price £145.00 - Original price £145.00
    Original price
    £145.00
    £145.00 - £145.00
    Current price £145.00
  • Chinook One Bolt Tendon Mast Base

    Original price £89.00 - Original price £89.00
    Original price
    £89.00
    £89.00 - £89.00
    Current price £89.00

    This chinook tendon joint is the best looking out there, tendon is held between 2 machined  stainless steel  cups. Allen keyed and lock nutted, to ...

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    Original price £89.00 - Original price £89.00
    Original price
    £89.00
    £89.00 - £89.00
    Current price £89.00
  • Chinook RDM 28cm windsurfing mast extension

    Original price £89.95
    Original price £89.95 - Original price £89.95
    Original price £89.95
    Current price £84.00
    £84.00 - £84.00
    Current price £84.00

    Chinook RDM 28cm Alloy Windsurfing extension Probably the most highly regarded extensions on the market. Large brass rollers significantly reduce ...

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    Original price £89.95
    Original price £89.95 - Original price £89.95
    Original price £89.95
    Current price £84.00
    £84.00 - £84.00
    Current price £84.00
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  • Chinook RDM 38cm Windsurfing mast extension,

    Original price £99.00 - Original price £99.00
    Original price
    £99.00
    £99.00 - £99.00
    Current price £99.00

    Chinook RDM 38cm Alloy Windsurfing extension UNCONDITIONAL 12 MONTH WARRANTY Probably the most highly regarded extensions on the market. Large bra...

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    Original price £99.00 - Original price £99.00
    Original price
    £99.00
    £99.00 - £99.00
    Current price £99.00
  • Chinook Rig Winch mega downhaul Tool

    Original price £55.95 - Original price £55.95
    Original price
    £55.95
    £55.95 - £55.95
    Current price £55.95

    Are you tired of pulling on the downhaul line? Struggling to get enough downhaul tension? This crank-type downhaul winch makes setting the downhau...

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    Original price £55.95 - Original price £55.95
    Original price
    £55.95
    £55.95 - £55.95
    Current price £55.95
    Sold out
  • Chinook Tendon Joint Replacement

    Original price £19.95 - Original price £19.95
    Original price
    £19.95
    £19.95 - £19.95
    Current price £19.95

    Windsurfing mast foot, This is a heavy duty replacement tendon joint for the chinook mast foot bases * Replacement tendon joint for mast base...

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    Original price £19.95 - Original price £19.95
    Original price
    £19.95
    £19.95 - £19.95
    Current price £19.95
  • Duotone 42cm SDM Epx Mast Extension

    Original price £85.00 - Original price £85.00
    Original price
    £85.00
    £85.00 - £85.00
    Current price £85.00

    These solid 42 cm SDM ( standerd diameter ) extension available for most SDM masts. Its well-known pin adjustment system enables reliable height ad...

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    Original price £85.00 - Original price £85.00
    Original price
    £85.00
    £85.00 - £85.00
    Current price £85.00
  • Duotone EPX Windsurf Base and Powerjoint UJ with 80mm Pin

    Original price £85.00 - Original price £85.00
    Original price
    £85.00
    £85.00 - £85.00
    Current price £85.00

    The world’s most widely used mast base in surf centres. The original Powerjoint with high cross section guarantees maximum durability. The central ...

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    Original price £85.00 - Original price £85.00
    Original price
    £85.00
    £85.00 - £85.00
    Current price £85.00
    Sold out
  • Duotone Gear Wheel Power XT 2.0 Mast extension

    Original price £39.00 - Original price £39.00
    Original price
    £39.00
    £39.00 - £39.00
    Current price £39.00

    Duotone / North Cog for Power 2.0 XTR / XT Replacement cog for both power xt and xtr and xti extensions

    Original price £39.00 - Original price £39.00
    Original price
    £39.00
    £39.00 - £39.00
    Current price £39.00
  • Duotone I Base 2.0 Tendon + Base Plate

    Original price £95.00 - Original price £95.00
    Original price
    £95.00
    £95.00 - £95.00
    Current price £95.00

    Duotone iBase 2.0 + iTendon Windsurfing Base Lowest design, extreme durabilitySo that the iBASE 2.0 can be installed or removed without the need f...

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    Original price £95.00 - Original price £95.00
    Original price
    £95.00
    £95.00 - £95.00
    Current price £95.00
  • Duotone iBase 2.0 Deck Plate Only

    Original price £45.00 - Original price £45.00
    Original price
    £45.00
    £45.00 - £45.00
    Current price £45.00

    Lowest design, extreme durability So that the iBASE 2.0 can be installed or removed without the need for tools, it has been designed to include a c...

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    Original price £45.00 - Original price £45.00
    Original price
    £45.00
    £45.00 - £45.00
    Current price £45.00
  • Duotone iBase 2.0 Joint Long 84mm Windsurfing mastfoot 2023

    Original price £105.00 - Original price £105.00
    Original price
    £105.00
    £105.00 - £105.00
    Current price £105.00

    Duotone iBase 2.0 Joint Long 84mm Windsurfing mastfoot Here we have a heavy-duty Duotone iBase 2.0 windsurfing mast foot. The iBase screws into the...

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    Original price £105.00 - Original price £105.00
    Original price
    £105.00
    £105.00 - £105.00
    Current price £105.00
  • Duotone Power XT 2.0 Mast Extension SDM Windsurfing 28cm

    Original price £149.00 - Original price £149.00
    Original price
    £149.00
    £149.00 - £149.00
    Current price £149.00

    An inspiring (r)evolution the POWER.XT 2.0 can do much more and do it better than the previous model. And as POWER.XT 2.0 AERO RDM 34 it is also th...

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    Original price £149.00 - Original price £149.00
    Original price
    £149.00
    £149.00 - £149.00
    Current price £149.00
    Sold out
  • Duotone Power XT Mast Extension Windsurfing Ratchet

    Original price £159.00 - Original price £179.00
    Original price
    £159.00 - £179.00
    £159.00 - £179.00
    Current price £159.00

    An inspiring (r)evolution – the POWER.XT 2.0 can do much more and do it better than the previous model. And as POWER.XT 2.0 AERO RDM 34 it is also ...

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    Original price £159.00 - Original price £179.00
    Original price
    £159.00 - £179.00
    £159.00 - £179.00
    Current price £159.00
  • Duotone RDM 36cm mast extension windsurfing EPX XT

    Original price £75.00 - Original price £75.00
    Original price
    £75.00
    £75.00 - £75.00
    Current price £75.00

    These solid 36 cm RDM extension available rdm masts. Its well-known pin adjustment system enables reliable height adjustment and secure locking. Th...

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    Original price £75.00 - Original price £75.00
    Original price
    £75.00
    £75.00 - £75.00
    Current price £75.00
  • Duotone Uni.XT Windsurfing Extension

    Original price £119.00 - Original price £119.00
    Original price
    £119.00
    £119.00 - £119.00
    Current price £119.00

    UNI.XT – the most technically advanced and yet the most lightweight standard aluminium extension we have ever built. Now also built using SLS ca...

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    Original price £119.00 - Original price £119.00
    Original price
    £119.00
    £119.00 - £119.00
    Current price £119.00
  • Duotone XT Power downhaul line rope Dyneema x2

    Original price £34.00 - Original price £34.00
    Original price
    £34.00
    £34.00 - £34.00
    Current price £34.00

    Duotone XT Power downhaul line rope Dyneema. 4.5mm by 2m approx length ( 2 pieces) This windsurfing downhaul line is perfect for your windsurfing X...

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    Original price £34.00 - Original price £34.00
    Original price
    £34.00
    £34.00 - £34.00
    Current price £34.00
  • North 34cm RDM carbon Windsurfing Mast extension

    Original price £225.00 - Original price £225.00
    Original price
    £225.00
    £225.00 - £225.00
    Current price £225.00

    North Sails RDM extensions ensure that you spend less time rigging and maximize your time out on the water. The Carbon is our lightest RDM extensio...

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    Original price £225.00 - Original price £225.00
    Original price
    £225.00
    £225.00 - £225.00
    Current price £225.00
    Sold out
  • Prolimit HD Downhaul Hook Big Wheels 4 Pulley

    Original price £19.00 - Original price £19.00
    Original price
    £19.00
    £19.00 - £19.00
    Current price £19.00

    Make it easier to downhaul your windsurf sail and get more tension on, with this four roller heavy duty pulley hook. 4 Rollers to set up an 8:1 rat...

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    Original price £19.00 - Original price £19.00
    Original price
    £19.00
    £19.00 - £19.00
    Current price £19.00
  • Prolimit Mast extension Windsurfing SDM 30cm

    Original price £49.95 - Original price £49.95
    Original price
    £49.95
    £49.95 - £49.95
    Current price £49.95

    Prolimit Windsurfing Adjustable Mast Extension Hinge coller with pins for easy and secure adjustment, Collar on the top of the extension so you ca...

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    Original price £49.95 - Original price £49.95
    Original price
    £49.95
    £49.95 - £49.95
    Current price £49.95
  • Prolimit Windsurfing Adjustable Mast Extension RDM

    Original price £49.95 - Original price £49.95
    Original price
    £49.95
    £49.95 - £49.95
    Current price £49.95

    Prolimit Windsurfing Adjustable Mast Extension Hinge coller with pins for easy and secure adjustment, Collar on the top of the extension so you ca...

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    Original price £49.95 - Original price £49.95
    Original price
    £49.95
    £49.95 - £49.95
    Current price £49.95

We sell many different windsurfing mast extensions. There are two types of windsurfing extensions, SDM Standard Diameter Mast extensions and RDM Reduced Diameter mast extensions. Shortly MDM with be arriving in stock here at Boardworx in the United Kingdom. This new size was developed by North windsurfing and is a size between these sizes.


The SDM windsurfing mast extension is designed for a fatter mast size of 48.8mm and is what most older windsurfing sails are made for, and also sails larger than 6.5m. RDM was developed for smaller windsurfing sails, and the internal diameter of these masts is 32-33mm. The new MDM has been designed for the windsurfer who wants the light weight of an RDM but wants the power given by an SDM mast.


Most Windsurfing mast extensions are adjustable in length so you can use them on different size sails. You can have fixed-length mast extensions, but these are rare. The sailboard mast extension is essential so you can rig the sail correctly. 


The Windsurf extension is made of Carbon or aluminium, and carbon extensions are great to use as they are so light but costly. 


Here at Boardworx, we think the Duotone XT mast extension is the best on the market. It has a simple ratchet system for downloading the sail to precisely the right amount of tension. 


Some of the strongest wave and slalom windsurfing extensions are made by Chinook, known for making solid windsurfing accessories.