While carbon booms are widely considered superior to their aluminium counterparts, the latter do offer solid stiffness at a price that is sure to catch the eye of many surfers on a budget.

Recently Germany’s Surf Magazine tested 16 aluminium booms, Unifiber’s Alu Essentials and Alu HD among them, to find the best combination of grip comfort, features, and stiffness.

Their primary test criteria were as follows:

• Adjustment ranges

• Tube diameters

• Stiffness

Here is what they found out.

(For the full test report, visit Surf Magazine’s website)

ADJUSTMENT RANGE

Although 50 cm is the most common adjustment range, some models go to 60 and even 62 cm.

Test team’s conclusions:

“Specified adjustment ranges should be used with caution as a fully extended aluminium boom has a higher risk of bending in case of a crash or upon a hard landing. We recommend that only the lightest of surfers (<75 kilos) should extend these booms to the max. Heavier users should ideally leave a five-centimetre safety buffer. For instance, if you are looking for a boom for a sail that takes a 198 cm boom, consider selecting a model with an adjustment range of up to 210 cm instead of the intuitive 200 cm.”

TUBE DIAMETER

It’s important to note that tube diameters in boom spec sheets refer to bare tubes, no grip is included. 

Many believe that the thinner the tube the better. Indeed, a smaller diameter reduces fatigue in the forearms making for longer sessions that are more fun.

Aluminium booms tend to be on the thicker side of the spectrum.

Test team’s conclusions:

“Surfers get used to the thicker tubes, however, if you find it difficult to maintain proper grip over time, changing to a thinner tube could definitely be an improvement. Shaving off just two or three millimetres can make all the difference in the world. Further comfort can be attained with carbon designs usually marketed as slim or RDM booms.”

As an alternative, Unifiber offers a tapered version of the Aluminium Essentials model, which unfortunately didn’t make the roster for this test. This particular design features a 26mm grip segment that expands to 29 mm towards the tail. This combination trades some of the boom’s stiffness and durability for comfort."

STIFFNESS

Features aside, it is performance that makes or breaks a boom. How the boom interacts with the profile of the sail and mediates between the rider and the rig is what really counts.

Boom stiffness directly influences the overall performance of the sail making it the key metric to keep in mind when shopping for new gear.

“Good stiffness values are important in order to achieve direct drive and good power transmission when pumping. How stiff is the boom depends on many factors: tube diameter, tube wall thickness, and the material used, just to name a few. When the tube diameter is reduced in favour of comfort, the boom becomes softer. To compensate for this, the tube walls can be made thicker, but this will result in increased weight. It’s simply impossible to have an aluminium boom that is as light as a feather yet stiff and thin at the same time.”

To test the booms for stiffness, the guys from Surf Magazine applied 35 kg loads to half-extended booms set to 5 cm from the adjustment range limit. This represents the load the boom is normally subjected to when used with a large sail. Note, however, that this approach doesn’t take all possible variables into account:

“A firm connection of the head piece to the mast is also decisive for the subjective feeling of stiffness – a factor that we did not measure but determined in a practical test with a rigged sail.”

Unifiber Modular head did particularly well in this test and the magazine’s experts had the following to say about this piece of kit:

“Even just clicked on, the head piece is already one of the stiffest. When combined with the optional performance bolts, it becomes even stiffer and offers an extremely direct power transmission from the boom to the rig.”

How did Unifiber booms fare in the Surf Magazine test? 

Aluminium Essentials Monocoque 160-210

Surf Magazine’s evaluation:

The Alu Essentials boom is wide at the front but rather narrow at the tail end. The front piece sits firmly on the mast, offering ideal power transmission, and can be removed in seconds for transport. The two-clamp system takes slightly more time to mount on the mast. The tubes are quite thick at 32 mm, but the design is one of the stiffest in the group (3.1/3.7 deflection under 35 kg load). Conclusions: Stiff with good features, but quite thick tubes.

Aluminium HD Monocoque 160-210

Surf Magazine’s evaluation:

The most salient feature of this boom is the smart easy-to-remove front piece that ensures a rock-solid fit on the mast and the best power transmission even without the optional screw connections (performance bolts). When extended, the boom is one of the top 5 in terms of stiffness (3.2/3.8 deflection under 35 kg load).)  Conclusions:  Slightly on the heavy side, this boom is rock-solid and offers great stiffness and grip comfort.