Typical stiffness of an inflatable SUP board
According to SUPboarder reviews, and their published results of inflatable SUP deflection tests*, the stiffest iSUPs on the market have a deflection in the high single number mm – 8 or 9mm. That is, then bend by up to 10mm when a person of 75kg stands on them when not supported by water. In this range come boards like the Naish Air Maliko and Starboard Airline 14 foot race boards. In the second tier are cheaper double chamber boards, which are classed as stiffer than normal by SUPBoarder if they have a deflection of 13mm. And many cheaper 14 foot race boards have a deflection of up to 25 – 30mm.
Do inflatable SUP board static deflection tests matter?
We’ve never normally been that bothered about one off static deflection tests. We don’t actually think that static deflection is a great measure of the performance of a board to be honest. A rigid hardboard can have a deflection of up to 5mm, but have no observable ‘bounce’ when you jump up and down on it. And when you paddle a hardboard, you don’t feel any observable bounce when you really put the power on. However, as any paddler of an iSUP knows, when you really hammer the power on, the board deflects and then bounces back as you enter the recovery stroke. And static deflection is not a good indicator of how much the board deflects under dynamic forces. Two boards with the same static deflection can feel very different in terms of how ‘bouncy’ they feel.
However, the benefit of static deflection tests is that they are controlled, and something that can be easily compared between one board and another. Which presumably is why they are still used! So we thought we should join the club and measure the deflection of our newest and stiffest board – our Carbon Go Race 14.
Breaking the rules
As you probably know, we’re not great for following industry rules at McConks. We didn’t have trestles, 75kg weights or tape measures to hand. So we did what we do best; we used what we had to hand.
Thankfully, Waterland Outdoor Pursuits, our test bed for the day, had two tables that were positioned about 2m apart, and free gap between them was 180cm (meaured by the length of a paddle!).
And rather than use a 75kg weight, we used some real people. We’re not going to say how much heavier than 75kg one of them was, but they were the closest to 75kg we could find, and more that 75kg. And to measure deflection we measured the undeflected height of the seam from the floor by using a paddle and some electric tape. And then remeasured the deflected height against the same paddle, again using electric tape to make a mark – example below.
This might all sound a little serious. But it was really just an excuse to lark around on a board.
The reality is that this is a very stiff board. Deflection tests measured between 6mm and 10mm, with an average of ~7.5mm dependant on how the board was placed across the supports and where the paddler stood. That’s not something that you often hear being mentioned in deflection tests is it? You normally only ever hear a single value with the supposition that it’s a very well controlled test. Sadly, really life would suggest that’s not strictly true, and an average, min and max value for each board would be a little more honest.
And don’t forget, our supports were further apart than the regulation 1.7m, and our weight was over 75kg. So that ~7.5mm compares rather well with SUPboarders stiffest board, the Naish Maliko air, which had a static deflection of 7mm. Especially when you realise that our Carbon Go race is over 2kg (20%) lighter than the Maliko.
What makes this the most rigid race iSUP?
It’s not rocket science really. Using the very best fusion drop stitch available (which we use in ll of our boards), plus dual full length carbon stringer on both the deck and hull do most of the hard work for us.
A new double layer hard fin box adds some welcome rigidity to the tail of the board. But the fin box is more about reducing drag than about stiffness, and it does a great job of that, by removing the fin box protuberance that you get on almost every other iSUP that uses proper race fins.
And an increased density deckpad makes it feel even stiffer under the feet. But really, it’s just simple common sense. Use the best materials you can, and don’t cut corners. And you end up with probably the stiffest 14 ft board on the market.
- Static deflection tests are carried out by measuring the deflection of a board under 75kg of weight when it is balanced on two supports 1.7m apart.