I’ve been working on a simple equation to roughly calculate ease of takeoff for boards based on your board aspect ratio (B.A.R.) and your guild factor (G. Factor).
I’ve collected data from over 100 different riders and kits at this point and have a few notable data points to share, but need to more deeply refine this equation over time.
Here’s how it works:
Calculate your board aspect ratio by simply dividing length by width. Add that number to your guild factor which is calculated by taking your boards liters, and dividing them into your weight in kgs.
My board progression as examples:
85kg rider.
Learned for 10 days on an 8’x30” 170l monster.
AR = 3.2
GF = 1.98
Sum = 5.18 (very easy to get on foil, I don’t think I ever turned it, no skill yet. Worth noting I was up and foiling on my first day as a self taught rider with a wing. I also caught every wave I paddled for in the ocean even though I didn’t know how to foil and just straight lined them back to shore)
First board I owned:
E3 5’10”x29” 123l 15.5lbs
BAR = 2.41
GF = 1.43
Sum = 3.84 (not to shabby to get on foil, crummy in the air)
E3 4’8”x26 83l 12.7lbs
BAR = 2.15
GF = .97
Sum = 3.12 (least favorite board I’ve ever owned terrible takeoff)
Barracuda 8’x21” 112l 13lbs
BAR = 4.57
GF = 1.3
Sum = 5.87 (easiest board I’ve ever had to get on foil and was fun in the air)
E3 5’3"x22" 83l 11.5lbs
BAR = 2.86
GF = .97
Sum = 3.83 (fun to ride and quite quick to take off in all but the most extremely light winds)
Custom 6’3"x20" 83l 9lbs
BAR = 3.75
GF = .97
Sum = 4.72 (extremely fast off the water, track boxes were awkwardly placed so I didn’t get a good feel for it in the air unfortunately)
Sunova Carver 5’10"x20" 85l (arrives next week, weight tbd)
BAR = 3.5
GF = 1
Sum = 4.5 (unridden, testing begins early 2024)
Things to consider:
With the 100 or so data points I collected from other riders I asked for the sum to be reported and if they felt as though their board was “easy to waterstart.” Here’s what the results showed.
Competent riders considered a BARG Factor of:
5 and higher to be capable for DW SUP.
3.5 and higher, to be easy to water start.
3.25 and lower, to be hard to water start.
BEGINNERS considered a BARG Factor of:
4.5 and higher to be easier to water start.
Anything below that was considered average/hard.
Conclusions this gives us:
This gives some rough guidelines for buyers who don’t have extensive access to gear demos to consider.
This gives rough guidelines to beginners who are picking up their first board and want to consider if it will be easy to learn on, and if, when they progress, it would be considered easy for the average rider to get up on.
This gives us guidance on how easy takeoff will be.
I personally really like that this drives the conversation away from liters, and more towards shape, to define efficiency.
What this doesn’t give us:
This does not take foil into consideration.
This doesn’t give you a guide to how fun a board will be once in flight.
This doesn’t take into consideration the nuanced details of hull design.
This doesn’t take windspeed and water currents into consideration.
You can break this equation, for example: an 8’x1’ sheet of plywood would have a BAR of 8 but a GF of 0 = BARG Factor of 8 which sounds highly efficient. But, this is yet to be tested and quite possibly not true.
I’ll continue to refine this equation to try and take in additional considerations and how each aspect can be weighted and more correctly evaluated. However, while this should not be considered the final word on how to pick your next board, it absolutely is a worthy calculation to take into consideration if you are unsure and want to continue to explore the possibility of other shapes.
I, personally, expect to focus my research on board efficiency in the 4-4.75 range.
