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Foil tuning questions
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d0uglass



Joined: 28 May 2004
Posts: 1248
Location: Bonita Springs, Florida

PostPosted: Sat Apr 06, 2019 6:23 pm    Post subject: Foil tuning questions Reply with quote

I'm getting hooked on foiling- feeling/learning something different every session, but accumulating a lot of questions. Maybe y'all can help with these two questions:

1. What are the pros and cons of positioning the front wing more forward or more back, and how are they affected by what sail size you're using, how powered you are, whether you're going for racy upwind/downwind/speed performance or going for maneuverability and jibes, etc? Do racers position the front wing more aft relative to freeride / freestyle foilers?

2. How do you tune the sail for foiling in terms of downhaul, outhaul, boom height, harness line position and length, mast base position in the track, etc.?

3. How do you maintain control in gusts, or do you just rig for the gusts?

Regarding fore/aft position of the wing: I'm riding a Slingshot Hoverglide Fwind 2019, which lets you change how far forward the wing is by mounting the mast to any of three different spots on the fuselage. I tried the wing forward position on my first session and got up easily but had a hard time getting enough weight forward to prevent overfoiling, and never got in the outer back straps. Since then I've been using the intermediate position, which makes it easier to keep the board down and fly steady in the footstraps. But sometimes it seems like I have to use an inordinate amount of back foot pressure to get up, especially when using a big sail and trying to fly in light winds.

Regarding sail tuning: I notice I'm adjusting how much I sheet in and out a lot more when foiling than when normal sailing.

Regarding gusts: I've been sailing in gusty conditions a lot because I live on the wrong coast of Florida with respect the prevailing wind direction at this latitude and I am often sailing in patchy offshore or side-off winds.

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dllee



Joined: 03 Jul 2009
Posts: 4562
Location: East Bay

PostPosted: Sat Apr 06, 2019 7:49 pm    Post subject: Reply with quote

Same as windsurfing but 1.5-2.5 meters smaller.
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coachg



Joined: 10 Sep 2000
Posts: 2767

PostPosted: Sat Apr 06, 2019 8:44 pm    Post subject: Reply with quote

On my board as I move the foil back I have to apply more back pressure & as I move the foil forward less back foot pressure. Foil back is easier-more natural for a windsurfer-to learn on but harder to jibe.

Sail tuning will be determined by the type of sail you are using and board setup determined by the board/foil combination you are using. I'm using a Naish Lift so tuning is done by out haul. Virtually no down haul is needed for the sail. My foil board is 73 cm wide with inboard strap settings so I run my boom lower at about shoulder height, my lines shorter, my mast track all the way back so I can stand upright & foil off my front foot. Even with a year of foiling under my belt I still often foil without a harness.

I rig for gusts first, adjust my rear stabilizer to drive the nose down second, angle the board over, push the rig forward & head up wind third.

Coachg
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LUCARO



Joined: 07 Dec 1997
Posts: 490

PostPosted: Sat Apr 06, 2019 9:02 pm    Post subject: Reply with quote

I think we are all experimenting a bit.

I believe you want the wing to be centered between front and back straps. Therefore the wing position (fwd/aft) may vary if you are using a dedicated foil board or regular board. Seems like pretty much everyone I know riding the slingshot hoverglide use the wing forward position, but they are all using dedicated foil boards and most of those dudes are not using the back strap.

Also, mastbase position (fwd/aft) likely affects the ability to fly the foil.

It is normal to have to pop the foil with temporary increased backfoot pressure (ollie-like) in light wind.

Did you go through the slingshot foil academy videos?

I was crashing heaps due to being overpowered until one of my mates told me to move my harness lines forward.

If you are using regular sails, I believe you want to rig with less downhaul than normal to try and keep your leech as tight as possible.
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grantmac017



Joined: 04 Aug 2016
Posts: 817

PostPosted: Sun Apr 07, 2019 12:24 am    Post subject: Reply with quote

I'm on a narrowish (72cm) board with the slingshot foil. Wing forward, boom lower than a fin, 30" lines more forward, mast base back for ~7m and shift a little forward as sails get smaller.
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d0uglass



Joined: 28 May 2004
Posts: 1248
Location: Bonita Springs, Florida

PostPosted: Sun Apr 07, 2019 11:52 am    Post subject: Reply with quote

This is hugely helpful. Thank you!

Yes, I watched all the Slingshot foil academy videos, but your tips are including stuff that they didn't cover.

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ss59



Joined: 10 Nov 2016
Posts: 69

PostPosted: Sun Apr 07, 2019 12:27 pm    Post subject: Reply with quote

may have already seen these:

https://vimeo.com/samross
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NOVAAN



Joined: 28 Sep 1994
Posts: 1211

PostPosted: Sun Apr 07, 2019 1:42 pm    Post subject: Reply with quote

I have the 2018 sling shot and 130 dialer board. For me at 165 lbs. i like the foil in the back position. It is very easy for me to fly the board and better for level flight. When I move the wing forward I had to put way to much weight forward in order to level my flight and keep from over foiling. Moving the foil fore or aft doesn't create more or less lift. It does change the balance point of the foil. Move it until you find the balance point that works for you. I like to rig a sail for the gusts. Once up on the foil it takes very sail power to keep you up. I got into foiling because I got bored with big windsurfing sails. I can foil at my lake on a 5.2 while the windsurfing guys are waiting for more wind on 6.5 or 7.0 sails. I'm no expert, been foiling 15 to 20 times now. I feel most comfortable in the front straps with my back out free to move around to pressure the board where needed. The more time you get on your foil the wider your wind range will be come for a given sail size. Just like windfsurfing.
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CoreAS



Joined: 23 Oct 2015
Posts: 65
Location: Dallas, TX

PostPosted: Sun Apr 07, 2019 2:09 pm    Post subject: Reply with quote

So far our group have settled on position B on the Hoverglide Foil. I have noticed not all the fuselages are marked A,B or C though!

Which front wing size are you using?

Mast base position is one of the single biggest tuning adjustments for pitch and keeping board level. literally 1/4" can make a difference.

We are also finding that rig weight/pressure can make a significant difference to freeriding foils (which the Hoverglide is). Foilers using cammed, big slalom sails are finding it more work and creates unequal pressure at times.

This video was just last week, I decided to rig a Sailworks wave sail from 1997 and it worked very well (slightly higher aspect and longer boom than newer 5.Cool

it was rigged with minimal downhaul on a 460 Maui Sails hard top mast which worked OK for my weight at 205, the mast luff sleeve was pretty deep all the way to the topů.Board is the Wizard 125 and Infinity 84 wing, position B.

https://youtu.be/G2q0Dn8JRz8

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LUCARO



Joined: 07 Dec 1997
Posts: 490

PostPosted: Sun Apr 07, 2019 2:48 pm    Post subject: Reply with quote

Also I noticed that some of the wings have longer stems, so for me it was not possible to ride the 84cm wing in the aft position, but it is doable for the 76cm.
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