The Luxury of Carbon Booms

If you are still wondering why all the fuss over carbon booms, then obviously you haven’t tried one. The best masts, the best boards, and the best fins are made out of carbon fiber. It is only logical that the best booms are made out of carbon fiber as well. Arguably, the stiffness of the boom is as important as the design of the mast or the sail. Every time you switch back to an aluminum boom you will see.

Carbon fiber is the perfect material for a boom because you can maximize stiffness and strength at very low weight. And carbon won't cycle and weaken over time like aluminum every time you sail it. To illustrate what is happening to your aluminum boom over time, just take a Coke can and bend it back and forth. Aluminum as a material gets softer and softer until it breaks. Carbon booms are so strong that they are preferred over aluminum at Ho'okipa, Jaws and other punishing wave spots in the world from Omaesaki to Cape Town.

But Carbon booms are far more than a luxury of lightness. Not only must the boom be your positive connection to the wind, but it also is vital to the performance of your sail. When a sail is loaded up by wind, it undergoes physical changes that either translates into speed and power, or into distortion and instability. In order to get the most performance from your sail, your boom has to be as stiff as possible and carbon fiber technology allows this to happen.

The development of the carbon boom has followed closely the development of sails. As loose leaches and twist allowed the draft of the sail to become more stable and easier to handle, the stiffness of the boom became more and more important. It makes no sense to have rigid battens and a stable draft sail, and give that benefit away to soft booms. That’s why when sailmakers submit their sails for "independent tests" by the magazines they specify Fiberspar booms to get the most performance from their sails.

Today, carbon booms are standard on the World Cup Tour, but sailors all over are discovering the importance of a stiff, lightweight boom. In the U.S., where Fiberspar Inc. developed the first carbon booms, one carbon boom is sold for every two carbon masts and this ratio is closing every day.

Ten of the top ten on the PWA World Cup Tour use carbon booms for the same reasons you should. The key elements to a great boom are stiffness, weight, feel/comfort, adjustability, reliability, and shape.

Stiffness: Whereas weight is vital to handling and acceleration, stiffness is the most important element to getting the most from your sail. The boom provides the outhaul tension on the sail and therefore must be as rigid as possible. The problem with most booms is that as the wind increases, the boom will bend outward and shorten, causing the sail to become fuller. A fuller sail in more wind is not only slower but causes significant control problems and drag. With a soft aluminum boom, suddenly there is more pressure on your back arm as a gust hits, and you get over powered and torqued off your board.

One might think that you only need stiff carbon booms on race/slalom sails 6.0m or larger. But more and more wave and bump & jump sailors are realizing the dramatic difference with stiff, light booms on smaller sails. Because smaller sails usually do not have camber inducers and stiff, full-length battens, the sail itself is less rigid. For this reason, you are relying on the boom alone to maintain sail shape and a stiff boom is vitally important.

Try this experiment the next time you are out on your 5.0m sail and the wind picks up and you come in to switch down to a 4.5m sail. Instead of switching sails, try your friend’s Fiberspar (F) boom instead. You will find that you can now control the power of the 5.0m sail with ease, go faster, jump higher, sail with more pleasure.

The Fiberspar boom has the greatest stiffness to weight ratio of any boom of the same length. With the Fiberspar boom you get all acceleration with no instability.

Weight: Any time you can take weight out of your rig, handling is easier. The swing weight of a heavy boom will pull you off your board in a jibe and make water starting and up hauling a chore. Any kind of sail maneuver, pumping, and acceleration is always best with a light boom. Carbon booms are lighter than aluminum and make sailing more enjoyable.

Feel/Comfort: Although stiffness and weight are the largest contributors to the feel and comfort of your rig, the diameter of the boom tube is important specifically for grip comfort. A large diameter boom makes gripping a struggle. (Try doing pull-ups on a tree branch with more than 10cm diameter.) But you can also go too small. For starters, any time you reduce diameter you loose stiffness and cause control problems. Also, you'll find that if you could hang from a pencil, your blood circulation would cut off quickly in your hands and your grip would weaken. Fiberspar booms are the perfect balance between stiffness and comfort. We use grip material that is specifically easy to hang on to, without being abrasive and causing blisters. We've tried other grip materials that are more durable in the parking lot, but we favor comfort, function, and ease of sailing over cosmetics.

Now Fiberspar offers Posi Grip booms. With a stiff carbon front end and carbon tailpiece you can now have a smaller (30mm grip overall) without losing that all-important stiffness. Posi Grips are the perfect combination of grip, stiffness, and weight for wave and free ride sailing, and are the booms of choice at the hot spots around the world. Once you try a Posi Grip, you simply cannot sail with anything else. Posi Grip booms are offered in 135cm, 150cm, and 170cm lengths. The longest Posi Grip is 170cm-218cm because if you go any longer in Posi Grip, you loose too much stiffness and performance.

Adjustability: The larger the range of adjustment the more you loose stiffness. Most sailors are willing to trade off some stiffness to cover two or three more sails with one boom. Of course the serious racers try to fit the length of the boom body to specific sails and they cut away excess adjustment extension to reduce weight.

The best adjustment system uses twist locks that do not corrode in salt water and work well in almost all sand conditions. Push pin systems do not work in carbon booms because they tend to jam (especially in sand or salt water) and the holes become larger over time causing the system to loose stiffness. More importantly, holes will significantly weaken a composite laminate. Of course, it is always best to rinse your boom from sand before adjustment is made.

Reliability: Carbon as a material does not weaken and fatigue over time like aluminum. It is no coincidence, therefore, that the only weak link in a carbon boom was the aluminum font end. The ultimate carbon booms are now 100% carbon…. including the front end. When sailors race across the Atlantic Ocean, expect no compromise in World Cup racing, or take on the biggest waves, their booms are Fiberspar carbon booms.

Boom Shape: The outline shape of the boom and the overall width is also important to your performance and the trim of the sail. A boom that is too narrow does not allow enough leverage over the sail, and you loose hiking ability and get overpowered quickly. A boom must be wide enough so that the sail is not distorted. Conversely, if you go too wide you loose positive feel and the rig becomes awkward. It is easy to make a stiffer boom by making it narrower, but if it is too narrow, then you inhibit sail performance and control.

The shape is important to the trim of the sail. It should be that when you are hiked out and your arms are straight, you are neither over sheeting or under trimming the sail. Also, you don't want a boom shape that causes awkward grip or wrist angles. Rather than a simple straight section behind where the sailor grips the boom, the Fiberspar boom has a curved section that allows the boom to fit the back of the sail. The shape of Fiberspar booms are carefully thought out for the trim of contemporary sails and for ease of adjustment. The shorter size booms are specially designed with wave and freestyle sails in mind.

Sailing With Carbon: There is only one thing you need to worry about when you sail with a good carbon boom for the first time.....Warning: Once you've tried carbon, you will never go back to aluminum again.