Inflatable SUPs are becoming more and more popular among the stand up paddle boarder crowd. This is partially due to an iSUP’s ease of use and transport as well as being cheaper than a comparable hard board. But are you aware of how inflatable SUPs are constructed and how proper inflation is achieved? In this article we are going to look at the construction, why they have to be inflated to such high pressures and why a special pump is needed.
Inflating iSUPs
Inflating iSUPs can be done via a specialized hand pump or via electric pumps. If using an electric pump make sure it can inflate to over 10 psi. The length of time it takes to inflate your SUP will depend on the type of pump you are using. With a regular hand pump it will take anywhere from 4 – 8 minutes. With a good electric pump it can take anywhere from 2-5 minutes. Although air pressure is not the only factor in the rigidity of your board, it is important and you want to make sure your board has the right air pressure so that it is able to support your weight and perform as it should. Because of the higher pressures needed with an inflatable SUP specialized valves are used. The type of vavle used on iSUPs is a Halkey Roberts valve. These inflatable valve types can hold much higher pressures compared to Boston valves and they are also user replaceable and serviceable. They require a specific type of valve adapter for the pump that fits the Halkey Robers, or H-Valve securely. A mechanical sealing system is used to insure that the board will stay inflated. ISUPs are very easy to inflate as the adaptor depresses the pin and allows air in but not out. Deflating a Halkey equipped board is even easier, just twist the pin and push down allowing all the air to escape. Then by rolling up the SUP towards the valve you’ll find that it compresses back to a very compact size.
How do inflatable boards handle all of that pressure and remain stiff? The answer to that is dropstitch construction.
Dropstitch is at the heart of all inflatable boards. It's a manufacturing process that creates two layers of material 'tied together' by an extremely large amount of very thin threads. So thin that when the board is deflated, the two layers can collapse together almost completely flat, allowing the board to be rolled up and stored in a much smaller space. Dropstitch comes in many thicknesses but the most common for inflatable SUPs is 4 or 6 inch dropstitch. The dropstitch material is not air-tight, so an outer layer of PVC must then be glued or laminated onto the top and bottom of the dropstitch material. The more air inside, the more rigid the board will be, but once you get above 25 psi you won’t see much difference. The difference between a board at 10psi and one at 20psi is dramatic. The more high tech and expensive boards involve extra layers of PVC laminated on, and the tension between these layers pulls 'rocker' (The upward facing parts of a board) into the profile, which needs to be done extremely accurately. The rails (the sides) are carefully overlapped and layered, with further material and taping applied to the rails to give extra strength.
Many inflatable boards can be inflated to incredibly high pressures thanks to the use of higher grades of dropstitch and multi-layer skins in manufacturing. Add in the benefits of efficiently shaped boards, and high quality fittings, and you get a near-indestructible package that can deliver performance as good as solid boards, and will last for years. Next time you are looking at an inflatable SUP and doubt their integrity in comparison to a hard board, think again! Remember these points and decide if an inflatable board is the right kind of board for you.
