I have tired posting on iWindsurf to request more data. I always get too many redirect error messages when I post; I have given up. I used Chrome, Edge-C, Opera same error message. When the data format is finalized I'm sure you get more data point from the 4 location forums; especially Northwest USA - home of SS
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One factor for Sail size variation may also be the speed of water relative to direction of travel ie Lake, Ocean T ide, River current.

one more data for you for what it's worth. 65kg, SS 76
Yesterday was on 2.9 Hot Sail Superfreak 25-30 knots, then it went up to 30-35 knots and it was still ok (foil speed maintained at around 15-16 knots in flat water light cruising). Board and foil was fine but the sail became a handful at that speed and short boom (like flagging a sail in 30-35 knots, twitchy). But still had fun for an hour before switching back to overpowered 4.3 and 69L pocket wave.

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drlazone said..
one more data for you for what it's worth. 65kg, SS 76
Yesterday was on 2.9 Hot Sail Superfreak 25-30 knots, then it went up to 30-35 knots and it was still ok (foil speed maintained at around 15-16 knots in flat water light cruising). Board and foil was fine but the sail became a handful at that speed and short boom (like flagging a sail in 30-35 knots, twitchy). But still had fun for an hour before switching back to overpowered 4.3 and 69L pocket wave.

Nice to see the super freak getting some love. One of the things I have noticed is that as the i76 has a top speed I do not feel I get as easily overpowered in strong wind as I do finning. The smallest sail I have foiled with so far is a 3.7 naish lift and I have ridden that with my 76 in wind gusting up over 30+ mph it and was a great session.

Anyone else feel that the speed limit on a foil allows you to confirmably handle more sail when the wind picks up?

Definitely the top speed and flying above all the crazy 30-35 knots chop, everything smooth out.3 scenarios from 2 days ago:
-going across the wind was the most unpleasant with the foil at its cruising speed and the sail very twitchy because it's too windy for the speed i'm going at (ie too much wind across the sail)
-going far upwind (just like when you're way overpowered on fins), is actually very comfortable, load up the sail and fly way upwind, esp with a foil the upwind angle when powered up is crazy (high aspect , short boom, lots of outhaul 2.9 SF helps a lot too)
-doing a downwinder on wind swell at those wind speed is easy, so much push behind your back, you just flag the sail and enjoy (apparent wind also decreased because you're flying straight downwind at 15 knots) and the superfreak goes completely neutral as designed to be.

My sessions ended up being quite fun with way upwind, then downwind swell ride , jibe without losing speed with wind in your back. Rinse, repeat.

sounds familiar Dr

This is all super helpful! I've been spending the last few months pondering sail sizes.

I'm new to the forums - I'm in the San Francisco area.

A couple more data points to add:

63.5 kg
Infinity 84

9-12 knots: 6.4m
12- 15 knots: 5.3
15-20 knots: 4.7
20-25: knots: 3.7
25-30 knots: 2.8m (would go smaller)


All my data comes from the Pacific Northwest and Columbia River gorge. A lot of my gear was mis-matched and old.

This is this spread I'm planning for the upcoming season, post quarantine, that's a little better optimized for the SF area.

Infinity 84, Wizard 105, 5.0/4.0/3.3/2.8

Thank you all,
I added the additional data points to the graph!

A bit surprising to see that the two windfoilers on 65kg do not appear to have a huge discrepancy in sail size, no matter if they are on the Infinity 76cm or the Infinity 84cm wing. But at least they are very close and also fully parallel in their sail size versus wind speed observations, which is encouraging for our modeling. Other aspects playing in is of course also then the type of sail they used and how efficient they actually are versus each other. Just in there can lay the reason why they do not appear to need a smaller sail despite the larger foil size...?

Good points on sail size of 76 vs 84. I've only had a few sessions on the 76, but I'm not sure if the extra lift is enough to influence sail size significantly.

I know I'm not very efficient, and I mostly used pretty run off the mill 4-5 batten wave sails. I'm curious if this year (2nd foil season) I can get more efficient and use smaller sails. Probably 75% of my sessions I've felt I had to much power anyway.