A personal experience has also helped me to shape my opinion about the importance of masts. About 2 years ago I was riding a new 2.9m Ezzy Tiger on a 340cm mast extended about 30cm through the head of the sail. But it did NOT ride nice like my other Ezzy Tigers that have the proper mast length. The sail felt terrible. It didn't accelerate. I struggled to get on plane. It was twitchy and unpredictable. At first I thought it was just me, or maybe poor wind quality or too small of a sail. But then I thought about the mast. I emailed David Ezzy, and I asked him if I could cut off 30cm from the bottom of the mast with a hacksaw. He said "YES". It made ALL the difference in the world. So I now have a 310cm mast for my 2.9m Ezzy Tiger that works AMAZING.
Since this experience I have been paying special attention when other local riders talk about how their sails handle, and I relate it to the mast they are using. You see, the sail that you ride will not function the way it was designed if it is rigged on a mast that is not built to the specifications that the sail manufacturer assumed when designing the sail. Masts can be stiff overall or soft overall. Masts can have more or less bend in the top, or more or less bend in the bottom. All of this will help determine the shape that your sail takes. For example, if your sail manufacturer assumed the mast to be used is stiff in the top, and you use a mast that is not stiff in the top, then your lower and middle battens may not give the sail proper profile in the bottom of the sail, and the top of the sail might be too loose and have too much twist. And vice versa if the opposite situation occurs. This is just one example, but there can be dozens of problems with your sail if the mast is not the correct mast. All of this has all inspired me to do a little more learning about masts.
The Technical Side of Masts: Let's start with stiffness. You have probably heard the terms MCS and IMCS. This describes the stiffness of the mast, and it stands for Mast Check System and Indexed Mast Check System. Generally, bigger sails need a stiffer mast and smaller sails need a less stiff mast. How do they measure mast stiffness? Basically, they lay the mast horizontal, support it at each end, hang a 66 pound weight in the middle, take some measurements, and then do some math. After the math is done you get an MCS and IMCS number. I'm not gonna get into the math details, but if you are interested in the details Sailworks has a great article that explains it. Here is the link: https://www.sailworks.com/pdfs/MCS_test.pdf
After determining the stiffness we should also want to know the Bend Curve. What does it mean? Well, it basically tells us if the mast is more or less flexible in the top compared to the bottom. To determine this they hang that 66 pound weight 1/4 of the way up the mast, and then again at 3/4 of the way up the mast. They take some more measurements, do some more math, and make some comparisons between the top and bottom. Then we get a nice little chart to tell us what the numbers on our mast mean:
0 to 6 Hard Top
7 to 9 Hard Top/Constant Curve
10 to 12 Constant Curve
13 to 15 Constant Curve/Flex Top
16 to 18 Flex Top
19 to 21 Flex Top/Super Flex Top
22+ Super Flex Top
The name "Constant Curve" is a bit of a misnomer because it sounds like the flexibility of the top and bottom are the same, but this is NOT the case. With a "constant curve" mast the top is still more flexible than the bottom. The name "constant curve" is more of an industry term to standardize a mast that is in the middle of the spectrum of soft tip versus hard tip. So a true more accurate name should probably be "standard curve" instead of "constant curve". But it's no big deal, just industry jargon that I wanted you to understand.
The mast is going to help determine the shape of the sail. We need a mast with the correct Bend Curve to match the luff curve of the specific sail we ride. The sail needs the correct amount of twist at the top of the sail and profile in the middle and bottom of the sail. It needs proper twist at the top because wind speed is faster at the top of the sail due to less friction with the water surface thus creating a different angle of apparent wind at the top of the sail compared to the bottom. And the bottom and middle of the sail need the proper amount of excess luff curve so that the sail can act like a foil and thus create lift for us. If the mast stiffness and bend curve is not matched correctly with the sail then our sail will NOT perform as the manufacturer designed it. The shape of the sail just won't be right. If the overall stiffness of a mast is too much or too little then it will affect the sail's ability to accelerate, to handle waves and chop, and to pump.
In addition to stiffness and bend curve we might also be interested in carbon content of the mast. Why? Generally, the higher the carbon content the lighter the mast. If the mast is lighter, then when it flexes hard, from say a big gust or a jump, it can return to its original shape more quickly. This can help us get on plane a little easier or accelerate more quickly.
Matching The Mast To The Sail: Different sails are designed with different mast requirements. You need the specific mast specifications that your sail was designed around. The easiest way to achieve this is to purchase the mast that the sail manufacturer sells for that particular sail model. Don't assume that a 400cm mast will work just because it's the correct length for a 5m sail. Know the MCS, IMCS, Bend Curve, and Carbon Content. Also, don't assume that a sail model that a manufacturer sells in 2018 uses the same mast as that same sail model from, say, 2010. Check with the sail manufacturer to find out exactly what mast your specific sail requires. Some riders have a variety of different sails in their quiver from different manufacturers, of different models, and from different years. In this case it is even more important to contact each manufacturer to learn what mast each sail requires because there is probably not much consistency among sail designs in that quiver. You can probably find the right mast, but contact the manufacturer to know what mast it is that you need. I personally ride all Ezzy Zetas, Tigers or Elites from years 2016 to 2018. I use ONLY the exact Ezzy Hookipa mast recommended by the manufacturer for each sail that I ride. Do I find that it makes a difference? Yes, absolutely! People often ask me how I can ride such relatively small sails compared to other riders of the same weight. There are many reasons, but one of the reasons is because I have the correct mast for each sail.
Some manufacturers make information more readily available regarding sail and mast matching. For example, while most manufacturers provide the IMCS that works best for their sails on their websites, very few provide the Bend Curve that their sails require. From looking at websites, I have found that Sailworks has very complete information on their website detailing exactly what Bend Curve you need for each of their sails. Ezzy and Maui Sails also have information on their websites about correct Bend Curve. But a lot of manufacturers do not have this information available on their websites, so you will need to email them to get that information. If you look at the numbers for similar purposed wave sails from Sailworks, Ezzy and Maui Sails you will see right away that there are differences in mast requirements. Here is a little chart I made with information obtained directly from each company's website:
Bottom Line: Just get the right mast. It will make you a better sailor, you will get less tired sailing, and you will have more fun.