Mini Test

Reduced Diameter: Mast Extensions

Mast Extensions

While you’re unlikely to lose any sleep through child-like excitement at the prospect of buying a new mast extension, there’s no denying that these humble bits of kit are as essential to windsurfing as the board or sail. Unfortunately the rather unglamorous nature of their job means that they tend to get the short end of the stick (excuse the pun) when it comes to marketing, testing and desirability. So to help you decide which one suits your needs best, Adrian Jones puts 13 of the latest RDM models through their paces…

With an ever-increasing trend towards reduced diameter masts (RDM), we decided that it was time to give some RDM mast extensions the attention they deserve and check out what’s on offer within the UK market. To ensure a easonably level playing field amongst the brands, we targeted extensions up to around the £70 price point with a length of about 28-30cm. Please note that, due to availability, some have been supplied in their larger 40cm versions, but we have quoted the prices of their smaller equivalents to give a better comparison.

£70 will cover most brands’ main alloy extension (and also a couple of carbons included within this test). If you have more money to spend, you’ll be able to step up to lighter carbon equivalents from these brands, and even more sophisticated systems such as North’s Power XT and Shox extensions.

The factors that define a well refined extension are actually quite extensive. While this test is mostly aimed at providing an overview of what’s available, we’ve tried to offer guidance on how each of the extensions delivers in the following departments:

Mast extensions

Ease of Use

There’s nothing more frustrating than an extension that doesn’t work well. It should be easy to adjust, easy to downhaul (and stow excess rope), and easy to attach / detach from the deckplate.

When it comes to adjustment, there are two main systems: collar-and-pin and hinged collar. The collar-and-pin system is time tested and works well, but it’s possible to lose the pin, and if you’re aiming for a ‘zero set’ on your extension, the collar jacks the height up a couple of centimetres.

The hinged collar is in our opinion the superior system. It’s used by Severne, Pro-Limit and NeilPryde at the moment, and we imagine more brands may go this way. It has two main advantages: you don’t have a pin to lose and it saves nearly 2cm of height, allowing for a much lower minimum / zero set. The only drawbacks seem to be cost and a slightly higher chance of jamming through corrosion if neglected.

Ease of downhauling relies on the alignment of the pulleys (more on this later), the quality of the pulleys / rollers, and the cleat system. None of these extensions use bearing blocks, so it’s simply a matter of how freely the pulleys run and how big they are (larger pulleys will generally make downhauling easier).

Realistically, there isn’t a huge difference between these extensions when it comes to pulley quality – the biggest difference is in the cleat positioning. Sails generally rig best on starboard tack, as the sail rolls more naturally, the numbers are printed on this side and the boom clamp is usually designed to be attached from this side. It therefore makes sense that the extension cleat is on the top side when the sail is in this position. This allows you to get your foot underneath the cleat / rope when downhauling, and, on the better designed extensions, allows you to stand on the base and pull upwards to release the rope from the cleat.

The last important factor is ease of attachment / release to and from the base. Most extensions have adopted the ‘standard’ pin method of attachment. This has three main advantages: ease of attachment, lower minimum setting, and perhaps most importantly of all, standardisation. If only more things in windsurfing were standardised! Those that choose to deviate from this system include the NeilPryde (although you can get an adapter to suit the pin) and the Amex Carbon. The only criticism of the pin is that it isn’t as strong as some of the alternatives. To be honest, we’ve used pins for years and rarely seen one snap at the pin itself, so unless you’re pushing things to the absolute extreme you should be fairly safe with the pin system.

To release your extension from the base you’ll find some form of button. In a country where we occasionally sail with numb hands, it’s important to make sure the button is easy to operate. The buttons are located on either the side or front of the extensions, and we consider the front position as marginally better because you can reach the button whichever way up your sail is. With side release buttons there’s a 50% chance that you’ll need to flip your sail over.

Extension pins


It goes without saying that no-one wants their extension to fail. A snapped extension could make it extremely difficult to get back to shore, and is
potentially very dangerous. The beauty of alloy is that it’s more prone to bending than snapping.
While carbon extensions are lighter and arguably stronger, the drawback is that when they do fail,
they tend to snap.

Performance alloys are available in a wide range of different compounds and temper designations, all offering a different balance between strength and price. It’s a complex subject to delve into here, but essentially most brands are using 6000 series alloy, with a few punting for the higher performance 7000 series or Ergal. Additionally, temper designation (cooling and aging process) is designated by a T number – the higher the T number, the stronger the alloy should be. T6 and T8 are commonplace within boom and extension manufacture.

Unfortunately, while strength is an extremely important factor, it’s pretty much impossible for us to test the absolute strength of these extensions over such a short period of time. The design, weight, alloy quality and gauge will give you some indication of potential strength, but word of mouth or trial and error are probably going to be the only real ways of ascertaining the strongest extensions.

Lengths & Measurements

Oh dear, oh dear – this subject is a nightmare! You would be right to assume that a 10cm setting on an extension should be the same as a 10cm setting on another extension. But I can assure you it isn’t! On some of these extensions there’s as much as 2cm difference in what they call ‘10cm’.
But to be fair it’s not really their fault. The problem comes in deciding where to measure from. If you measure from the centre of the pulleys (on the extension) it wouldn’t be right because you can’t actually pull the foot of the sail to the centre of the pulleys, so 10cm wouldn’t be 10cm. Where the measurement should be taken is from where the bottom of the sail will reach when fully downhauled. This datum point is usually not the pulley block because that is encased in plastic, which prevents the sail reaching it, so it comes down to a guessing game as to where the foot of the sail will stop against the extension.
And of course all sails are shaped differently at the foot, hence they will contact against different points of the extension and result in a different datum point.

So, there is no ‘standard’ because it’s virtually impossible to have one. This means that you really need to take the measurements as a rough guide and nothing more. If your sail says it needs 10cm of extension, there is absolutely no way you can guarantee achieving it accurately, unless of course you are using sail, mast and extension all from the same brand – and even then you need to be careful.

Zero Test

This never used to be a problem with SDM extensions, but with RDM – because the base is often wider than the shaft of the extension – it’s not always possible to set the extension at ‘zero’.
This may or may not be important to you. If, for example, you have a 4.5 sail with no adjustable head and a luff of 398-400cm on a 400cm mast, you might find it quite frustrating if the minimum set of your extension is 5-10cm, resulting in a big gap at the foot of your sail and your boom cut-out artificially jacked up by 5-10cm.

Rope Stashing

Because the shaft is so narrow on an RDM extension compared with the base pin that fits within it, there isn’t room to stash rope in the extension itself. This means that rope needs to be routed safely away from the cleat and then tied off externally on the extension. Some extensions have better routing than others. The only extensions that do allow you to stash rope within are the two that don’t use the pin system, namely NeilPryde and the Amex Carbon.

Pulley Alignment

Traditionally sails had an eyelet at the foot. You would either thread your rope through the eyelet or use a pulley hook, which would be aligned with the pulleys running from the port to starboard side of the sail. This aligned perfectly with the mast bases of the time. Then brands decided to incorporate a pulley block into the bottom of the sail, but interestingly most opted to orientate this pulley block from front to back of the sail rather than port to starboard, which meant it no longer aligned with the pulley block on the mast base/extension. There is a correct (albeit slightly complex) method of threading the rope to cater for this ‘misalignment’, but just as soon as people were starting to get their heads around this technique, some brands started to release bases / extensions that now aligned with the sail – i.e. the pulleys on the base ran outwards from the extension shaft, rather than across it. This made threading the downhaul a lot more intuitive and required slightly less force to apply the downhaul. However, to complicate matters there are now several sail brands that have reorientated the pulley block on their sail (to run from port to starboard) rather than the extension. So (and no great surprise), we have another non-standardised system that means you may or may not end up with orientated pulley blocks on your sail and extension. To be honest, it’s not a massive issue as even if they aren’t aligned there isn’t really a big problem, it’s just slightly less intuitive when it comes to threading the rope correctly.

Downhaul Rope

Rope Quality

The most common style of rope supplied on mast extensions is some version of a polyester prestretched braid. But there is now a more ‘high tech’ option available known as Dyneema, or more specifically Formuline (the white line pictured left), which is manufactured by Marlow ropes specifically for windsurfing. Formuline has higher breaking strain than polyester, which means that even when it’s frayed it has a lot of strength and also less friction, so it’s easier to downhaul. The downside is that it’s more expensive, so within this test only NeilPryde and Point-7 have opted to use it.


Because we received such a range of extension lengths, we decided not to quote the individual weights as they weren’t directly comparable.
However it’s worth noting that they ranged in weight from 0.4kg (for the two carbon extensions) to 0.8kg for the longest alloy. That’s quite a difference. Arguably, having the weight at the base of the mast is perhaps the least noticeable / damaging to the performance of your equipment, but it’s still worth considering.


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