As I watch Naish going with a very small sail (~5m) for wind of less than 10 mph on his foil board and racer using 9-10 meter sails with foil racing, I have no idea what I use for low wind days. I prefer to use smaller sail if I can foil efficiently as a beginner. So far, I was able to manage 12-15 mph with 7.0 on i99 foil but I am wondering using much bigger sail will give me a better flight. I predict that recreational foiling is significantly slower compared to the race foiling but can I increase my lifts using much bigger sails? On a separate note that as I watch racers on foil, it seems they are able to ride with an angle pushing their board and fin from the side of the board while recreational sailors are more straight.
Are you a little guy with pro level pumping skills?
Bet the Naish 122 is closer to 115 liters.
In 15-20 mph, windsurf on 5.2 and 85 liter board.
For foil, 4.4 is starting to get too big.
200 lbs racers on Formula 10.5, on foil 8.5.
Your skills has everything to do with your choice of sail....and your weight.
Select to expand quoteSA_AL said..
As I watch Naish going with a very small sail (~5m) for wind of less than 10 mph on his foil board and racer using 9-10 meter sails with foil racing, I have no idea what I use for low wind days. I prefer to use smaller sail if I can foil efficiently as a beginner. So far, I was able to manage 12-15 mph with 7.0 on i99 foil but I am wondering using much bigger sail will give me a better flight. I predict that recreational foiling is significantly slower compared to the race foiling but can I increase my lifts using much bigger sails? On a separate note that as I watch racers on foil, it seems they are able to ride with an angle pushing their board and fin from the side of the board while recreational sailors are more straight.
It all depends on the foil/board combinations. Racers use 160-180 liters boards, 100-110 fuselage and relatively small surface wings. Add the width of 91cm, with a tail almost as wide, and you need a 8.0-9.0 in light air to start going (the drag induced by the width is huge). And yes, race board/foils are designed to go upwind and downwind. (And no, nobody had a 10 in the PWA last year.)
Take a Freeride foil with a shorter 80-90 cm fuselage, big big wing and a narrower 70-85 boards with comparatively narrower tails, and I have seen people taking off in ridiculously low winds with sails two square meters smaller than what was been used at the same time on a Starboard Foil 177/F4.
7.0 seems already big, and it might be that you have to work on your pumping technique? I am terrible at that and it seems to be what makes a difference in light wind with respect to other sailors who have mastered it.
It needs to be said that racers use really big sails for reasons not really important to most foilers much in the same way that Formula racers needed a 12.5 but most freeriders were fine with a 9.5-10.5 limit if they wanted to go that high.
Windward/leeward racing pushes the boundaries on the two most underpowered directions of sailing. What's fully powered going upwind can be totally overpowering on a reach. Second, being underpowered in a race sucks especially if it's enough to fall off the foil. You go from the podium to mid pack (or worse) in a flash. You rig to be fully powered in the lulls and learn to hang on in the gusts.
Unless you are racing, it's almost a distraction to see what racers are using. They will be on a 9.0 when you are on a 5.5. Then again, you probably don't give a crap if you fall off the wing during a jibe in a lull. They do. A lot. 
If you have a bigger sail, try using it. I had limited my foiling to 6.5 and under for a long time, until I finally went out on my 8.5 on a light wind day, where flying on the 6.5 would have been difficult. The 8.5 had me going the entire time, and was definitely more fun that the 6.5 would have been.
If you don't have a bigger sail, should you buy one? If you don't mind spending the money, like the feel of bigger sails, and foil where you get a lot of marginal days, then go ahead. Otherwise, it may make more sense to work on pumping, tuning, and efficiency, which should enable you to push the limit down a knot or two with your current gear.
I can use my 10.0 foilracing sail in the same range as my 4.9 wavesail on the foil and even use my 9.0 when I can use my regular freestyleboard with 4.9. Racers are not representative at all of what foiling has to offer.
That being said, its all in the technique and definately not in the sailsize. Make sure you have a sail you can pump well, I am 88kg's and my favorite size for efficient pumping is a 4.6 wavesail. I can get that up the foil in 10-12 knots.
Much bigger than 7.0 will not change anything in how early you can fly, especially with the slow wings you are using. Your foil isnt made for big sails, i've tried the SS H2 (older), Naish and F-One 1400,1800 and 2200 with various windfoil sails. All those foils were offbalanced by a sail much over 6.0 (6.5 is ok). But they also really really dont need it if you pump correctly! They give such a load of lift that flying with a 5 in 10 knots of wind should be accessible to everyone.
For reference: with a 900cm2 / 85cm span wing and a board which matches the sail (either 71, 77 or 85 wide foilboards) 4.6 does 10-12 knots, 5.7 8-10 knots, 7.0 gives me 7-8 knots and 8.6 6-7 knots. Your wing gives a lot more lift so 8 knots with 7.0 should be easily reachable.
With my racing kit (100.5cm board and PWA racefoil) 9.0 and 10.0 both get me flying in 5-6 knots.
I learned from all of your comments. Fascinating technical information that are not available at any other site as far as I know.
Thanks for your inputs.
