April 4, 2014 timchandler

Understanding the Mysteries of SUP Volume

You want a performance SUP experience but let’s face it – none of us want to battle a sinking board while paddling out, no matter how great it may surf once it’s finally up to speed and riding.  During a recent conversation with an experienced SUP surfer who’s riding boards in the upper 8 foot to 9 foot range – he confided as we chatted opinions on surf SUPs in ‘volumes’ and shapes that he hasn’t really understood volume well enough to apply it when considering a new board.

For those I work with on the water – here’s my quick take on how to factor volume when considering a surf SUP.

Volume is in Liters

Corban 2014 SUP Line UpWe weigh ourselves in lbs here in the US – an Imperial measurement. Yet companies building SUPs talk about volume of their SUPs in liters, a metric measurement.  Just standing and chatting in the shop – where many of the boards aren’t labeled for volume – we’re already well down the road of mixing things up by speaking in Imperial lbs vs. metric kilos and making educated guesses as we try to factor for floatation.

The reason “lbs vs. kilos” is important is that if we change our language to use metric weights, we have the basis of a great baseline ratio for displacement/floatation where one liter will float one kilo (roughly 1:1 – here’s more on displacement).  So using metric it’s one to one… and to make that comparison we’ll need a metric measurement of weight to compare.   To get your weight in kilos – multiply your weight in lbs times .45.  Bingo, if you’re a 195lb rider like me, you’re suddenly 87.75 kilos (88 for discussion).

So back to our floatation ratio:  one liter floats one kilo.  SUPs are different than surfboards and there are other factors involved here – so even with our 1:1 ratio if you’re 88 kilos, there’s likely no way that 88 liter SUP board will perform properly.   Enter the ‘ability factor’.

Let’s Use the Guild Factor

Have a look at this online surfboard volume finder.   It’s one of the closest things we have as a community to a baseline ‘ability factor’ application that demonstrates how surfboard volume maps to a rider… meaning it takes your weight, factors ability, and spits out the Lost board volumes and models that’ll work for you.  The “ability” part of the equation is a multiplier called the Guild Factor or ‘GF’.  In the past few years this has been applied to SUP boards as well, and while controversial to some who call it a marketing gimmick – I believe it holds value as an illustration of volume as a factor in ‘SUP fitting’.

For SUP, the Guild Factor normalizes rider ability into three broad measures and assigns a GF (multiplier) to ‘Advanced’ (GF = 1.3), ‘Intermediate’ (GF 1.7), and ‘Novice’ (GF 2.0) abilities as a starting point.  Pick one of these based on your ability… and read on.

“SUP Fitting” – Find Your Baseline

SUP Volume Calculator at Try Stand Up Paddle SportsTo find the magic baseline number – you take your weight in kilos and multiply it by your GF.  In my case – 88 x 1.3 (on a good day) = 114.4 liters.  Now keep in mind as you immediately try to apply the resulting number to any SUP you’ve surfed – this is what I consider your baseline! You CAN ride above and below this number. Most short SUP surf boards I consider my everyday boards are 105l to 110l.

The board volume you’ll be on is a fixed metric – but if you’re like me, sometimes you’re ripping and sometimes your not… and your weight may fluctuate slightly (I go up and down about 5-7 lbs).  We’re also NOT accounting for water and wave conditions and/or other factors that impact what board you’re capable of riding like clothing weight (wet cotton weighs more).  But with this number, we have a baseline that you can float above and below for volume. If I show you a list of 20 SUP surf boards you can demo ranging from 105 liters to 205 liters… you now have what I consider to be your low baseline.  You can try a board that’s 110 liters, but based on the template of the SUP, I’ll be warning you that the conditions need to be right and it’s probably going to be a challenge (you may be prone paddling out with a paddle under your chest).

Weighing Your Options

Yeah, punny.  So if we’re talking at the beach this week when you find me in my traffic-cone-orange shorts — and you say to me that one of the SUP To YOU demo SUPs looks amazing but you don’t think you can ride it — I hope you’re not offended when I ask how much you weigh.  What I’m doing is ball-parking your weight in kilos against the board you’re asking about as a starting point.

The other biggest factors that matter in my opinion are shape, shape, and shape… and then maybe conditions.  The reason I say this – is the rocker, tail and nose volume (where the board carries it’s volume) are HUGE factors in smaller SUP surf models.   I can show you an 8ft 110liter board that I ride constantly that breaks the baseline rule above – barely “floats” me as my feet ride almost under water – yet I feel is more ‘stable’ than other boards with more volume!  The only way to truly find the ‘range’ of volumes and boards that work – is to set aside your preconceived notions of what you “need” to ride and TRY as many as you can!


I surf down to 100 liter boards today – currently 187 lbs.  I lost a bunch of weight and got down to 175 lbs last summer before breaking my foot.  Interesting to surf the quiver from 175-190.  Really an eye opener on how weight effects performance.  Dropping again now…

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