Hey LeeD, I hate days like that.
I agree with some of the comments above. I tend to rig more for the gusts so that I can survive them. When it lulls, you have more sail range to keep flying, but slogging on a floaty-enough board works, too.
Yesterday's conditions on the Snake River were like that. 5-30. I rigged both 5.0 and 6.4, but each one was good for, maybe, 30% of the time.
I think the answer to such conditions is to use a huge front wing with a really small sail on a floaty board. A 3.9 with a i84 would have worked, but, alas, I have neither.
I wonder if a small front wing and bigger sail might have....been the same misery.
My Naish 1236cm is big for my 170 lbs so maybe a 600 sq kitewing 11 might work.
My big problem is lulls in the wind.
We're downwind of an 11 mile fetch.
Berkeley can drop from 20 to 5 in minutes, and the 2' tall windswell persists forever because Crissy Fields and Treasure Island are still blowing 25 and cause the windswell.
Slogging is really difficult, small sail, 122 Naish, old man with weak legs.
I got out last night in some wind I've not really foiled in before. 18mph, gusting to almost 30 on my anemometer. Rigged the smallest sail I have (6.0 Flyer) and used the i84. Way overpowered, but still had fun. The foil plate was at 3/4" forward from zero, and I felt really had to push down with my back foot to get it up flying. Probably should have been a 1 3/4" or 2" forward of zero. I feel like I naturally want to be back foot heavy from my windsurfing days... but it doesn't feel right, or work for me to be that way when foiling. Could have easily used a 4.7 sail.
It may have been the strong wind last night, but I felt like the i84 was a bit twitchy, perhaps it was the rearward location of the foil mast. But it definitely felt different than the i99. The i99 is SO SMOOTH and predictable to me. I really like it.
Time to start shopping for a 4.7-5.0 sail.
Any suggestions on a closeout or used sail that would fit an RDM 430 mast?
exca8tor said, "I have had both the i84 and i99 in "B" position. The sail mast has been pretty much in the center of the mast track everytime I've been out." And "I had the i99 at 0" and the i84 at about 1" or 1.5" forward of "0" (hopefully that makes sense) ".
Slingshot recommendation for the I 99 foil: WIND: This wing works ONLY on The Levitator boards that offer an adjustable track mount that allows you to slide the whole foil system forward.
Wow, this is way different than the slingshot recommendation. Can't argue with success.
I'm thinking about trying the I99 on my wizard 150 in the C position. The trouble is that it is a big pill to swallow if I can't get it to work.
What do you guys think is a good size spread for a quiver of sails? Currently I have a 10.0, 8.0, 7.0, 6.0 and 4.8.
Currently looking for something smaller than the 4.8... was thinking 4.0, but kind of feel like 3.8/3.9 might be smarter.....?
If there's any wave wind foiling in my future, it will be downwind wave foiling.
I got out this afternoon for a few hours on my Duotone 4.8 Super Session with the I84 front wing. Had a dang good time, even though it was only 40 degrees. Could definitely have used a smaller sail... 3.8/3.9 may have been pretty close to perfect.
Hi Lakeeffect
Don't get to ingrained in the leading edge measurements. We all get consumed by micro adjustments on the fuse/front wing location but don't forget mast base and foot strap positions are just as important.
When I give riders my exact measurements it never really pans out (it might be a starting base but every fraction yields a different feel) so tailor make yours from experimenting. from our windsurfing days we would adjust the mast base 1-2" but for foiling 1/4" on mast base with a hole back on a foot strap creates entirely different ride.
Thank you exca8tor for the I99 S48 number and SA_AL for SL55's number for the I99 S42.
LeeD, I agree with your that COE,Center of Effect for the Sail, is important and every difference size sail I use has a different COE, but COG, center of gravity, is just as important. It's the other half of the equation. The Sail provides the Thrust and the Foil generates the Drag. The Sail is the Energy Source, the Foil is the Energy Sink.
Core AS, I agree that in and of itself the wing leading edge to stab leading edge means little. In addition I agree that the mast position and foot strap position are just as important as the neutral point and the corresponding COG along with the COE for the different sails I use. Written between your words I suspect there is a message that if I went to the beach today for a four hour foiling session I would be a lot farther ahead than if I spent four hours of calculating neutral points and COG's at home. I agree, but the Lake Erie is about 40 degrees today and the air temperature is in the 20's. So thinking about foiling is the best I can do.
I'm using a math model whose inputs are the wing aspect ratio, the stab aspect ratio, the wing area, the stab area, the wing span, the stab span, the wing root chord, the stab root chord, and the wing leading edge to stab leading edge distance. These are used to calculate a COG for a 10% static margin.
Below is a summary of the calculated neutral points and center of gravity for a number of Slingshot Wing and Stab combinations. They are numbers for the long fuse.
Paducah, You make a good point. I currently sail an I84 with a 48 stab. My next purchase will be an I99 using the current 48 stab. The numbers say I need to move my stance a half inch forward. Moving my back foot an inch forward would put me in balance. However if I maintain my stance and move the sail mast forward or increase the height of the boom it would do the same thing. And I can change the boom height or sail mast position on the water where changing the foot straps requires returning to the beach and walking to the car for a screwdriver.
I understand buying things you want and don't need. My wife tells me I have poor impulse control. I sit in my home in a reclining chair with the internet in my lap where I can shop the world for things I want. I want that I99 foil but don't need it to mid May of next year.
The COG (center of gravity) is the result of body position in this sport.
The COL (center of lift) is an aerodynamic spot on the chord of a lifting wing, usually about 1/3 back from the leading edge. This varies, of course, with planform, span, etc.
It is the COL that you want to get at, or near, the midpoint between front and back feet. If the COL is too far aft, you can't get the foil to lift and fly. If it is too far forward, you can't control the lift.