Have we come to a better idea of what the volume to weight ratio of a foil sup should be? It doesn't look like the pros are moving to these sinker sized boards yet.

Hi exiled. I have a pretty good idea on what average volume is needed for the average person weighing 70 to 90 kilos in most conditions.
I think it will be basically the same volume as the SUPs the pros were using before foiling come of age. If they can paddle & keep stable on a sinking SUP then they can do the same with a foil. BUT why bother with a sinking SUP when you can ride a smaller prone foil board to get a better wave count. After all its only the foil that the rider is performing on & the rest is just the weight of the board & strength of the rider to push & pull the weight.
Where this would change in a comp is the use of the paddle to assist with power turns etc.
So should a comp have different categories like foil only with no assistance by a paddle? That may include both prone & SUP. Of course a SUP rider can use a paddle to travel back to the break & catch a wave. But not use the paddle when up on foil.

Not really interested in prone boards, I just want to know if people are moving up or down in volume when they move from a sup to a foil sup.

IMHO too much foam on a foil board can actually make stability worse . You do want the board to sit in the water not on top of it. At the bottom end of the scale your weight plus 10 to 15 litres is plenty as long as your board isn't super narrow & short . The door shape is definitely has the best paddling stability shape but catches a lot of wind and has a lot of swing weight when you are foiling . The Fanatics are like this and are great learning boards but you quickly out grow them. The JP's are the other end of the scale and are harder to learn on but much better in flight.

So to answer your question a shape in between the JP & Fanatic with apx 15 litres extra foam on top of your weight , would go pretty close for your average punter.

Hey exciled
I'm 95kgs and now ride a 6'6 x 28x 103L foilboard. I dont have any problem with stability. My normal go to sup is the Acid and speeed..106L /115L..my first foil board was a retro fitted minion 7'8 x 115L. So yes, I was able to drop in length and volume.
Was a little worried about stability and right size when choosing but great advice on this forum from others -Piros and Matt and they were spot on.
Go as short and with as less volume as you can
Chur

my initial feeling is at least at a minimum get a board is equal to your comfortable sup surf board liters or as piros said 10 to 15ltrs extra in real world not what the pro action shot that you see in the media. The foil keel does add some stability but pitch and roll is not fun when you go shorter and or narrower. If you cant paddle the board then you won't be able to catch a wave and then fly.

Agree with JEG. The same as what you are comfortable on your smallest SUP in volume & less width & length.
My comfortable smallest SUP is basically 8ft by 29 wide at 110 litres for my body weight 80kgs.
My most comfortable foil board (its converted for foil but good shape for it), is 7ft by 31.5 wide at 115 litres. Which has better stability than my comfortable SUP.
My smallest foilboard is 6ft 8" by 26 wide at 96 litres. Which has less stability than my comfortable SUP.
So I think my ideal only one foil board to equal the stability of my comfortable SUP would be 28 wide & as close to the length & volume of my smallest foil board at 6ft 8 and 100 to 105 litres due to the wider width.
So I would say 1ft shorter by 1 inch less width at 10 litres less volume.
So yeah. We are going to smaller foil boards than SUPs. And yes can sink a little more at the same width of SUPs.
My dilema is that I foil surf at two different locations the typical beach with hardly any side swell & chop so my small foil board is great. The other is near a breakwall & lake entrance where side swell & chop is so frustrating on my small foil board but so much easier on my larger foil board. And its the wave count that is most important for me. I am usually the last one to leave when everyone has left when conditions get worse. So I need a two foil board quiver.
Obviously when flying the smaller board wins.

I'm trying to sort out where I should look gear wise for my next step. I converted a 7'0x30 120l simsup to a foil board. It was my small wave grovel board and I surfed it fine for years and its a fine stable platform now as a foilboard. I'm 105kg, so it has kinda been the bottom for me sizewise. 115L surf sups have been too much work for me in the past, so I'm wondering if a 115L foilboard will work. The kicker is that most of these 115L models aren't really that much smaller than my current board anyway.

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exiled said..
I'm wondering if a 115L foilboard will work. The kicker is that most of these 115L models aren't really that much smaller than my current board anyway.

I'd advise against getting too low in volume on a SUP foil: the extra volume help a lot popping on the foil on non-breaking waves. The Gong shaper for instance, who is an expert SUPer and foiler uses a 6'9" x 130 liters board for his 100kg(*). He says that a lower volume is not worth it for SUP foiling (surf foiling is different).

Also the specific shape of the new generation boards (big bevels) make a big difference in taking off and managing touchdowns.

(*) here:

So after looking around, it seems like the Takuma ZK Mini might work at 6'2''x27 1/2''x5'' : 130L. It looks like they put there finbox pretty far forward though, not sure I like that. Any other manufacturer sticking this much volume in a small board?

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exiled said..
Any other manufacturer sticking this much volume in a small board?

Fanatic have some beefy ones and they also fit their boxes way forward because of their swept front wing.

Does Fanatic have some models not listed on the website? The closest one I'm seeing size wise is 6'4x27 @ a rather skinny 96L

IMO but I'm only beginner, for SUPFoiling you need volume to catch small / non breaking waves, and a short lenght for once you're "flying".
I just bought a Takuma Mini ZK 6'2 and it's perfect! You have the volume for take off but you don't feel it after. Plus the board is very light.

well the foil definitely adds stabilility so dont be afraid to go narrower. Also when you're only at half mast or below height then a narrower board will catch the wave face less when you're going along the face.

Volume wise, Piros is bang on.... strangely it wants to sit in not on the water for best stability. You can kind of imagine that if a structure with a keel (like a foil) was being designed by engineers for max stability in choppy water then theyd have it sat low rather than high catching wind/chop and corking around all over the place. I've heard this argument made for SUPs and having a had a couple of 80litre boards there's definitely something to it... but it seems more pronounced for boards with a foil. If its glassy then for sure extra volume makes you paddle faster and generally more comfortable... but its surprising how stable a partially submersed board with a foil is in chop.

The other thing ive noticed (and it may just be me) is that these shorter/narrower bevelled railed boards seem to sit slightly lower in the water anyway. I'm guessing its a surface tension thing. Regardless of stability, all things being equal and stood in sheet glass water.... my toes are as wet on a 6'0x26 95litre SUP foil as they are on 7'2x26 85litre SUP.

As for catching the bumps earlier.... depends if you're on a big wing or not. Watch videos of ppl pumping up onto the foil in flat water. It's all a short burst and it seems to be the wing doing the work to get you up not the volume. Higher volume may make you more mobile in the line up and catch more waves in general... but on a big wing for the actual take off it wont make much difference if you have the technique down.