How do windsurfing booms work and what should you know

Everything you use when windsurfing has to be reliable, well made and capable of coping with the workload.

Nowadays most booms are either aluminium or carbon, both materials giving very different weight and feel, which ultimately delivers performance differences.

I’m a big fan of Unifiber booms and have used them for many years, without any problems, so this article will based around that brand and what I know about their booms, but this is relatable to other brands as well.

Unifiber Booms

As with most brands the Unifiber range of booms offers everything from kids booms, to performance kit. This includes their Elite range of carbon booms for slalom, allround and waves, alongside the aluminium kit, which is entry level.

There are a range of shapes and grip diameters that make a big difference to the use of the boom and style of sailing.

Let’s crack on and discuss the various factors to see what really matters when choosing a boom.

Aluminium Versus Carbon Booms

There’s a massive difference in performance and feel from carbon to aluminium, but for a beginner the ultimate factor is the price saving. You could pick and aluminium boom for £100, but carbon booms start at about £400, so the reasoning for many is price.

If we run down the pros and cons it will make more sense:

  1. Stiffness – Carbon is much stiffer than aluminium This means the rig won’t deform so easily when the boom is under pressure. This could be when the sail is rigged or when you’re getting into stronger winds.
  2. Control – Carbon is way more responsive and you will find that you feel more and are able to respond and tweak in a more sensitive way.
  3. Power – It’s hard to measure, but with less flex and a stiffer boom you’re going to transfer more power to the board and this means getting going quicker and controlling the power better.
  4. Durability – A common fail is aluminium bending then snapping. It can happen in a shore dump, catapaults and crashes or just over time.  Carbon booms don’t bend so they’re inherently stronger in that way, but they don’t like to be bashed, especially on hard surfaces.
  5. Weight – carbon booms are so much lighter than aluminium booms and this makes a big difference for all levels of sailor. That said, you still have the head of the boom so those parts are similar weights, it’s just the boom bars that are lighter.

Conclusion

If you can afford carbon, then get it, without doubt. There is no reason not to enjoy the benefits of a carbon boom. That said, windsurfing is fun no matter what you use, so if you only have an alloy boom right now, crack on and keep learning.

Unifiber Essentials, HD and Elite booms

Most brands offer a range of booms to suit different disciplines and budgets.

With Unifiber you get the 3 different levels including:

  • Essentials: budget friendly aluminium booms
  • Heavy Duty (HD): aluminium and carbon booms built for durability
  • Elite: carbon booms built for uncompromised performance

unifiber boom logos and icons

A boom is modular but not all brands sell parts

Unifiber booms can be broken down into the 3 key parts. A boomhead, bars and tail.

unifiber boom diagram

The great thing with Unifiber is you can buy parts and build out your own boom, so if a part break or you need a slightly different setup, you can buy parts to get the perfect setup.

The Boomhead

The head of the boom is the front of the boom that clamps onto the mast, so logically this has to be rock solid. With your weight pulling on the boom  and the twisting and turning of the clamp against the mast, it is important to spread the load on not force all the pressure into a small spot.

So how have Unifiber made such a good boom head?

The first and most obvious thing is to look to create a solid connection between the clamp and mast, so that all the energy from the sail is reliably managed by the sailor. But if you make a connection that is super stiff and use the wrong materials, you end up putting pressure on the very edges of the clamp which inevitably break the mast.

A great boom head is one that can form itself to the shape of the mast. You don’t want any play so you feel and create movements as and when needed, whilst creating a connection that is fluid depending on the mast bend and can micro adjust when necessary.unifiber boom boomhead and clamp design

You can see in the second picture, how the clamps are separated, but what you cannot see if the high density rubber inserts that give a softer pressure point against the mast.

 

unifiber boom head clamp collars spread the load

 

Boom Grip Diameter

If you’ve sailed much you may have had the chance to try different kit and if so you’ll have tried different booms.

The grip is a really big part as it is the bit you’re holding onto. This grip is a big part of your enjoyment, so let me explain.

If you are holding onto a thicker boom bar, then your fingers will be more open and that is a quick way to create fatigue. This is more apparent when it is cold and that inevitably shortens your windsurfing session. 

Inversely, having a thinner boom bar, allows you to wrap your fingers round the bar more easily and this give you a more relaxed hold, lengthening your sailing time.

Slalom booms are often thicker as they’re generally long, whereas wave booms are more often narrower as you’re holding the boom without being in the harness.

You’ll also find the shapes of boom bars can vary be it round, v-grip or more oval.  I’ll be honest – you don’t really find that many shaped bars now and most carbon booms are round.  The v-grip concept is that it can create a stiffer bar, but to be honest I don’t really feel that much in carbon booms.

unifiber boom boom grip styles

 

Having a Narrow Or Wide Tail

Generally when using bigger sails, like slalom kit or bigger freeride sails, you’ll find that you need more room at the clew end of the boom, so the sail doesn’t rub against the boom. You may have rigged the sail with a low tension outhaul to give the sail more belly and low down grunt, but in doing so means the sail may billow out and be disturbed by the boom bars.

Wave sails or smaller kit will have less belly and so doesn’t need  such a wide tail end.

unifiber boom narrow and wide tail

 

Boom Body Shape

The regular or classic shape of boom came about when the bars were made from two parts. The problem was that the front arm had to kink at the wrist which was uncomfortable.

Compare that to the modern shape where the bars were now being made from one piece and the C-Shape appeared. This allowed for a more relaxed wrist so reduces fatigue.

You may find a variation on larger booms as the sailor is further away from the rig, but in the end it is more comfortable.

Whilst these differences are small, the upshot is massive and will create a much nicer windsurfing experience.

unifiber boom body shape

 

 

Boom Head Mast Diameters

You have 2 different widths of mast being, SDM or RDM. RDM is  thinner mast reduced diameter mast.

When you’re getting  mast to suit a sail you’ll generally know what work for it as the info is noted on the sail bag, but if you have a RDM and need a SDM, you will find an adapter in the Unifiber kit.

Boom Adjustments

All sails will require different lengths of boom and the values are written on the sail.

Whilst those values are noted, you may need to make adjustments depending on the height of boom or how you want to fill the rig i.e belly for light wind.

Something to note is that if you use a boom at its longest length, the boom will be less stiff than if you use it in a shorter length.

This means you may end up needing a couple of booms to cover all your sail ranges.

unifiber boom length adjusters

 

 

 

Outhaul pulleys

This is  really big one for me. I love the loop and go concept as it speeds up the rigging process, allowing easier adjustments.

You can see from the pictures below how the Unifiber boom works. The other thing you can do is leave a knot in the end of the outhaul rope so you don’t need to re-feed it.

unifiber boom tail loop and go

 

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