I was foiling at Yamba yesterday (Whiting beach, great spot) in 20 knots plus and even with my smallest sail - 4.7 M, I was out of control with the gusts coming through. I was on a Infinity 99, which I know was a big part of the problem. I could have changed down to my 69 cm wing, but I would have had to remove the rear wing too and change the fuselage to a different mounting position as the I99 puts the the COL a long way forward. I weigh 95 kg without gear.
I don't have many other foilers here to compare notes with so it got me wondering - what do you guys do when the wind gets up to 20 knots plus? Use small sail and small foil, pull out a slapper or go home?
3.7 sail and i65, when normal windsurfers are on 4.7-5.3 sails and I'd be on my 4.8/waveboard. Maybe 20-22kts?
4.7 and i76 would be 14kt conditions, and I use the 4.0 in 17kts. 4.7 in 20kts with a big foil would be far far too much for me at 77kg.
Nowadays I only windsurf if there are good breaking waves, and get more foiling sessions than wavesailing ones. Foils are great in waist-chest high fat waves.
For 20-23 knots I use my AFS Wind95 with the F800 wing (1120 cm2) and an Aerotech Freespeed 5.8, on a Goya Bolt Pro 135, I weight 90 kg in gear. It is now fun, but took a while to get comfortable and not feel like I was barely in control.
That is my smallest sail, so have not tried any stronger winds.
35 knots is superfun if you have the right gear 
Vid from May 2020 - W105, Infinity 65, Simmer Blacktip 3.7
Maybe up to 25knots.
Do you have the 99 in B or C? What is your other wing. The Gamma 68?
Yes, it's the Gamma 68 although I didn't know that. I think I'm using C position reversed on a formula board that has the mount a long way back.
It looks to my like COL will be in a similar place using the same mounts. I'll know soon as heading out to try it in 15 knots.
Foiling is very sensitive to body weight ... At 100kg in gear, for me in 20 knots around 5m is ideal, 25 knots 4.2, 30 knots+ time to go pink 3.7 
For blasting slalom style, can go bigger
For loose carving like Azymuth, smaller is better
Select to expand quotegregwho said..
Yes, it's the Gamma 68 although I didn't know that. I think I'm using C position reversed on a formula board that has the mount a long way back.
It looks to my like COL will be in a similar place using the same mounts. I'll know soon as heading out to try it in 15 knots.
Most people put i99 in C position to move it forward (big guys might get away with B). And most people put the gamma in C as well. So you shouldn't need to flip the fuse if you are running i99 in C. If you are making the i99 work in B then you can probably make the gamma work in B when the wind picks up.
Normally i would recommend you add the 76 to the 99, but most people put the 76 in B (see below). Or you just splurge on an additional fuse and stabilizer and have 2 complete sets
I find the 99 becomes a handful over 15-18 knots
At a geriatric 195 lb my favorite wind range is 13 mph to 20 mph. I don't like less, because that means slogging. I don't like more, because that means the wind is on-off on-off on-off, etc. Too gusty and hard to get dialed in. Sails 5.0 to 7.0, foils LP-940 and AFS-2-F800, boards Stingray 140 and formula.
Even finning, I did not like more than 20 mph. Too much work for the amount of fun derived. As an old guy I like mellow.
Fortunately, where I live the above wind range is quite common.
Select to expand quotesegler said..
Even finning, I did not like more than 20 mph. Too much work for the amount of fun derived. As an old guy I like mellow.
It very much depends on the water state. A nice flat water spot in 25-30 mph is just about the most fun there is. It's great if the "chop" is just 2-3 inches, and freaking unbelievable in less (which requires either lots of weeds or a nice sandbank).
But I fear that foiling has changed my preferences a bit. At my home spot, I don't feel the excitement anymore when the wind goes above 30 mph that I used to have. I foil in 12-20 knots, and windsurf if it gets higher than that. I'll blame the foiling, though, not my age. And I am very much looking forward to 30 knot sessions in the right spots soon again - Corpus Christi this winter, and maybe (knock on wood!) Oz again next year .
Thedoor, thanks for the clear explanation with pictures. I think you're right, if I want to foil in all winds I need an I76.
Another piece to add to my collection of 2 boards, 2 booms, 3 masts, 6 sails, and (so far) 2 foil front wings. I'm starting to see the attraction to winging.
Cheers,
Greg
Max wind for me, after around 140 foil days is around 20-23 knots....4.2 sail, Naish 600 sq cm wing, 170 lbs.
That day, I could only course slalom foil, so changed to a 109 freeride board fully powered.
Select to expand quotegregwho said..
Thedoor, thanks for the clear explanation with pictures. I think you're right, if I want to foil in all winds I need an I76.
Another piece to add to my collection of 2 boards, 2 booms, 3 masts, 6 sails, and (so far) 2 foil front wings. I'm starting to see the attraction to winging.
Cheers,
Greg
5.3 to 3.3 sails, 1 foilboard+i76 and 1 waveboard should cover 11-40kts for an 80kg person. For someone at 90kg it's maybe 12-13kts on the low end, though lower if you opt for the i84.
IMHO, once you have foil kit I can't see the appeal in flat water (or poor waves) windsurfing, as the foil is so much more fun. A good wave day on a proper waveboard is still fun of course!
I don't see that.
At around 78 kgs., a 3.7 is good only up to 25 knot winds.
And I use a 600 sq cm kitefoil on my Naish 122 board.
When windsurfing in 25 knot gusts, 85 liter board, I'm already using a 4.2 or 4.5.
That means, for windfoiling, I'd need a 3.2 or smaller sail......and that's only 25 knots.
Sorry, probably didn't communicate it so well, the (normal windsurfing) waveboard was meant to cover the stronger winds. Normally we'd get a decent wave once it blows that strong.
I wouldn't windfoil above 25kts.
I have had a handfull of sessions in sheltered water with gusts into the low 30's with a 4.0. I am 100kg and using Moses 790. As I get more time on the water I get more comfortable carrying more sail. When I first started the speed and fear of crashing freaked me out and I would rig small to compensate. I Just got in from a gusty session in a narrow tidal creek, there were 5 knot lulls and 28 knot gusts right next to each other, I used a 4.5 and the 790. This set up made the most of it and it was fun! A year ago I would have been struggling, not in control and not having fun.
That sounds realistic.
Give me 25 more kilos, and 30 knot breeze becomes reality.
Flat water and enclosed body of water adds to possibility.
I'm 150lbs and 35kts maxed out on my 3.5m and infinity 65 wing(850cm2) is the most wind I've been in with smooth 1m wind swell. In waves 1m or bigger it elevates the fun factor even more in strong wind.
Never learned how to short board because of crappy gusty conditions during the summer, foiling has given me no reason to ever windsurf again. Never seen a windsurfer or winGfoiler (in person) carving harder or having as much fun in the waves as I do. In 40kts> not many people I know have the skills or gear to windsurf those conditions, I know I definitely don't. Foiling on the right gear that suits your riding level every thing is just easier which translates into pulling off moves you wouldn't dream of on a windsurfer.
Select to expand quoteCAN17 said..
I'm 150lbs and 35kts maxed out on my 3.5m and infinity 65 wing(850cm2) is the most wind I've been in with smooth 1m wind swell. In waves 1m or bigger it elevates the fun factor even more in strong wind.
Never learned how to short board because of crappy gusty conditions during the summer, foiling has given me no reason to ever windsurf again. Never seen a windsurfer or winGfoiler (in person) carving harder or having as much fun in the waves as I do. In 40kts> not many people I know have the skills or gear to windsurf those conditions, I know I definitely don't. Foiling on the right gear that suits your riding level every thing is just easier which translates into pulling off moves you wouldn't dream of on a windsurfer.
100% agree Connor, even when we have decent wind, its still super gusty and windsurfers last maybe an hour (tops) where I can foil for 2-3 hours and have a ton more fun foiling upwind for 2-3 miles and then down wind in the swell.
Regarding the OP question, Foiling is no longer for that 10-15 knot breeze, its way beyond that now.
Most wind I have foiled in was 35 gusting 38 knots on a 3.7 and Naish wing (200 lbs), and now I regularly foil in 32+ knots with 4.0 and TC 68 wing
Wow, 35 gusty 38 is what I call dead steady. Where I live, if the wind gets really strong I have to contend with 15 gust 38. It's not even fun. You can't rig or tune for it. I just wait for steadier days that do come.
Select to expand quoteCAN17 said..
I'm 150lbs and 35kts maxed out on my 3.5m and infinity 65 wing(850cm2) is the most wind I've been in with smooth 1m wind swell. In waves 1m or bigger it elevates the fun factor even more in strong wind.
Never learned how to short board because of crappy gusty conditions during the summer, foiling has given me no reason to ever windsurf again. Never seen a windsurfer or winGfoiler (in person) carving harder or having as much fun in the waves as I do. In 40kts> not many people I know have the skills or gear to windsurf those conditions, I know I definitely don't. Foiling on the right gear that suits your riding level every thing is just easier which translates into pulling off moves you wouldn't dream of on a windsurfer.
Nobody can sail a windsurf in 35 knots with a 3.5 and 150 pounds of weight!!!!! I am so glad you can do it on a foil! 
It must be so much easier than windsurfing!
Sorta agree was Dave......
But I have a few times, even up to 45 gusts at Tomales when the best 235 lbs guy was on a 2.8. Yogi on 2.5. M White on 2.5.
I didn't fall with 3.9, sailed for 1.5 hours, but not once had any fun. Hit butt landing jumps, spun out lots, feathered and sheeted out most of the time, but stayed on my feet.
Nothing I'd do again, but when you drive 1.5 hours, your buds are out....you gotta go out.
That was 30 years ago, not lately.
Sorta agree was Dave......
But I have a few times, even up to 45 gusts at Tomales when the best 235 lbs guy was on a 2.8. Yogi on 2.5. M White on 2.5.
I didn't fall with 3.9, sailed for 1.5 hours, but not once had any fun. Hit butt landing jumps, spun out lots, feathered and sheeted out most of the time, but stayed on my feet.
Nothing I'd do again, but when you drive 1.5 hours, your buds are out....you gotta go out.
That was 30 years ago, not lately.
Select to expand quotesegler said..
Wow, 35 gusty 38 is what I call dead steady. Where I live, if the wind gets really strong I have to contend with 15 gust 38. It's not even fun. You can't rig or tune for it. I just wait for steadier days that do come.
I didn't really explain that comment very well, the peaks of the gusts were 35 to 38 knots on that day!
our typical wind spread is 10-15 knots....so like you on any given day its 22 gusting 35+ (and that's considered consistent ) down at the Texas coast they think gusty is 30 gusting 32 
My record is 50-60 knots with 2.0 in a storm. But comfortably would be 30-40 knots tops with 3.0. After that I only do it for the views 
.
Select to expand quoteduzzi said..
Nobody can sail a windsurf in 35 knots with a 3.5 and 150 pounds of weight!!!!!
Maybe not a 3.5 on the ocean. But I've seen a 150 lb woman windsurfing in 35 knot averages, with gusts into the 40s, on a 3.4 several times in more protected waters. One of those times, a girl that competed in the Techno class apparently was out training on her Techno gear (i.e. a much larger sail) at a nearby spot, but I did not actually see that.
Select to expand quoteboardsurfr said..duzzi said..
Nobody can sail a windsurf in 35 knots with a 3.5 and 150 pounds of weight!!!!!
Maybe not a 3.5 on the ocean. But I've seen a 150 lb woman windsurfing in 35 knot averages, with gusts into the 40s, on a 3.4 several times in more protected waters. One of those times, a girl that competed in the Techno class apparently was out training on her Techno gear (i.e. a much larger sail) at a nearby spot, but I did not actually see that.
3.5 in 35 knots sounds like the right size for fin? I'm 200 lb tho.
Select to expand quoteWhiteofHeart said..boardsurfr said..duzzi said..
Nobody can sail a windsurf in 35 knots with a 3.5 and 150 pounds of weight!!!!!
Maybe not a 3.5 on the ocean. But I've seen a 150 lb woman windsurfing in 35 knot averages, with gusts into the 40s, on a 3.4 several times in more protected waters. One of those times, a girl that competed in the Techno class apparently was out training on her Techno gear (i.e. a much larger sail) at a nearby spot, but I did not actually see that.
3.5 in 35 knots sounds like the right size for fin? I'm 200 lb tho.
Maybe, but a 150 pounder would be taken to the moon!
I am under the impression that people tend to over estimate the wind they are sailing in, or maybe report the gusts ... it is a bit like fishermen with the fish they catch. 35 knots is a gale, and taking into account a normal variation with gusts of 30 to 40 very few can sail in those conditions. Gorge sailors might be the exception because they get a lot of wind.
And yes, bordsurfr, in close water it might be feasible. In open water it is much worse and I think I rarely got to windsurf in more that 25 knots average conditions. It is when my 3.7 comes out, at 160 lb/72Kg. I do remember of a few times when I was overpowered on 3.7, but if just powered up one can last a long time on the water with a windsurf. Just a matter of balance.
Unrelated but I did sailboat a few force eight in open ocean, in Corsica, and in the same location run into a force 9 that escalated to 10 by the time we took shelter behind an island and waited it out for two days. That was quite terrifying with smoke on the water. But it is a matter of skill. Solo sailors in the Vandee Globe run into very strong gales and they are foiling ... so maybe a windfoil can go in force 8 and 3.5
New foiler this year and 42 year windsurfer. Fanatic flow 1250 on a fanatic stingray 125. 75kg. For foiling I use 7 in 12-14, 5.8 in 15-17, 4.9 in 18-20, and 4.2 in >20. 4.2 was borrowed and was too big so just bought a new 3.9. Hope it will let me go up to 25.
Seen Teddy and Gephardt out in 35+ at Chrissy ebb, doing laps from Bridge to Anita Rock together no harness and 7.4 sail. D-2 boards.
I was maxed out on 3.4 and 75 liter wave board. 50 sailors on shore watching -10 sailors in the water doing funny things.
