Forums > Windsurfing Foiling

F4Foils Tuning Tips - Towards 30 knots!

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Created by berowne > 9 months ago, 18 Sep 2021
Sandman1221
2776 posts
24 Sep 2021 9:18AM
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Paducah said..

Sandman1221 said..
"Compare this to my PB of 28 knots on AFS 800 set where I was bracing for impact fearing death...! But with 2 years less experience!)"

I would never take the AFS F800/1080 wing that fast, the F700/770 is a much better wing for higher speeds, and the F700S after that.



AFS had a R800 wing which is what I suspect berowne was using since he had a bit of nice AFS kit for a while.


okay, that makes sense Paducah, thanks

berowne
NSW, 1210 posts
24 Sep 2021 7:37PM
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AUS02 said..
Not an F4, but I've been trying to get some speed out of my GTR+ on my iSonic 83 (slalom board) with a 6.0m FoilGlide. Top speed so far is 27 knots. video shows a few runs of 24-25 knots in super flat water. Front foot only in the strap and harnessed in with a waist harness.



Dave I just watched your video again, and your gybes are so smooth.

berowne
NSW, 1210 posts
25 Sep 2021 10:13AM
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Front wing relative positions with 4 fuselages
90
100
115
115+






berowne
NSW, 1210 posts
25 Sep 2021 10:34AM
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Just added 1cm marks to my box




JBO83
7 posts
25 Sep 2021 8:45AM
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berowne said..
I'm seeking tuning and 'feel' tips to break the 30kt foil speed barrier. I've made the switch to F4 and feel like they definately have the potential for great speeds. After 3 months I have improved speeds from 20 knots to 27 knots as of yesterday. I'm adding my tuning tips here, and am keen for anyone to share there experience.

I typically ride with high boom, long adjustable harness lines and a seat harness (have done for 30+ years). For context, I'm 188cm and weight 80kg. My Foil board is FMX Hyperion 91cm - awesome board!. Some of you may be familiar with it... www.seabreeze.com.au/forums/Windsurfing/Foiling/Foil-board-Repair-Job-The-new-nose-you-all-need

I wrote an F4 Foil review soon after getting my new wings: www.seabreeze.com.au/forums/Windsurfing/Review/F4-Race-and-Slalom-Foil-Sets-2021--Long-Review

560 (700 wide) front with, small 190 rear wing on 90cm short fueslage Mast base 128 (full back!)
This was the setup I used for max speed. I had the mast track all the way back, just in front of the bold hole so about 128cm on my FMX 91 Hyperion. Front straps are in the 2nd front holes and no rear straps.
At first I had the 0.5mm small shim in and my back foot was nearly hagging of the back of the board to control ride hight.
After removing the shim my back foot was over the rear holes of the back straps (I sail without rear straps).
Trim still felt too far forward, occasionly I would dip the nose too easily when sheeting in but felt very balanced and was happy to push more.

On deep downwind runs needed very little downforce to balance the lift and achieve top speeds... probably need to commit more to the harnesss as speed increases but was very light feeling at 27 knot run!
(Compare this to my PB of 28 knots on AFS 800 set where I was bracing for impact fearing death...! But with 2 years less experience!)

I've read some riders on the short small F4 slalom setup actually put a shim in backwards! I'm yet to try this.

81cm board? I've occasionally felt my feet were too far outboard, rotating the heels inwards. Is a narrower board better for top speeds on small wings?

100cm & 115cm fuselage
Other times I've used the 100cm fueslage with mast base at about 133cm felt about the right balance point, probably more nose down taps rather than too high moments. I've used this length more and think I prefer the extra stability (sligthly less responsive).
I tried the 115cm fueslage with the small wing once, brings it further back c.f. the 100 and felt quite good too.

Prefered sail is 5.5 or 6.3. I'm using old slalom sails with a new clew hole mounted just above the long batten.
The 560 is quite a small wing, so needs about 15kts board speed to flly so decent planing speed, and you can get stuck in a lull :(. Responds well to power in the sail and is surprisingly comfortable with a 8m sail when the wind gets lighter!

620 (800 wide) front wing, 190 and 210 cm rear on 100cm fueslage
Definately has more and earlier lift than the small wing, making gybes easier to fly through too. My speeds are about 2kts slower on the same day c.f. the 560 with this wing, but I'm sure it has more potential.

I started riding with the mast at 136cm but quickly moved back to 133cm and reduced shim from 1mm to 0.5mm.
The 100cm fueslage has the wing further forward than the 115 so does need more harness commitment. I haven't tried all fueslage options with this wing yet.

850 (900 wide) front wing, 190 rear on 100cm fueslage
I've spent the least amount of time on the small race wing. I expect it would be really helpful for bottom end slalom racing especially at the gybe marks for a small tradeoff in top speed.

945 (1000) front wing, 210, 230cm rear wings, 115+cm Fueslage
The big course racing wing has a LOT of lift and the power really increases with speed. Takes commitment to ride fast
I need the 1mm shim to control the power of this wing in anything but the lightest winds.
I started with mast base at 138, almost all the way forward in the box, but have brought it back to 135 now.
Top speeds for me are 23kts so far with 9.0 and 10.0, but I've heard it can "easily" do 28!

Ride Feel - Board Setup
To go fast you need to be comfortable. When I started foiling it felt nearly impossible to get enough downforce on the nose. At one point with my Slingshot foil I even tried building some footstrap adapters to bring the straps further forward. Yesterday I rode the F4 @ 27kts with the mast base right at the BACK and felt really balannced, which goes to show setup is everything!.

Tap down
The most significant change I've noticed lately is how to identify when your mast base is too far forward. It is fine to ride and you can fly just fine but what happens as you accelerate is that the downforce from the sail (even without extra from the harness) pushes the nose down and you tap the waves. This unsettles your balance needing back foot pressure, which then risks going to high and either breaching or porpoising.
If this happens, move the mast base back a cm at a time.

Back Foot too far back?
With too much rear wing shim on I noticed that I had to have my back foot a long way back to maintain ride height. Again not a problem sub 20kts but as you accelerate the balance points are too far apart... reduce rear wing shim helped me here.

Ride Feel - Sail Control
Once the board is under control trim is mainly from the feet, which will discuss next, and sail control. The biggest tip I can think of here is that when you are close to breaching or tapping down, your ride dynamics are only off by a few %, so don't over adjust!. Make small adjustments, trying to maintain harness line pressure and use small movements to adjust ride height, then move back half way to where you were.

You can also send the nose down by sheeting IN the back hand, which seems counter intuitive if your about to breach! Don't sheet out too much... ever!

To make small adjustments moving the hips back/forward/inboard/outboard a few centimeters can have the desired effect, but try to remember to keep the harness pressure pretty stable.

For smaller sails at speed, a high boom with long lines seems to be popular. I'm definatly finding it to be helpful, and am happy I've got adjustable lines on most of my booms.

Reaching at speed can require an amazing amount of downforce, Sometimes I think I've had about 70% of my weight through the harness lines a few times, which can hurt with a waist harness, and is why I prefer a seat harness. This is probably too much downforce and is likely a symptom of mast base too far back, but I'd appreciate some tips here!

? How much downforce to you use thorugh your harness, when sending it!?

Ride Feel - Foot Control
The use of foot control for up and down should be pretty obvious (pitch control).
While riding fast, especially through chop, perhaps less obviuos is the importance of roll control!
Unlike slalom on a fin (windward rail up) you will want to keep the windward rail down foiling, to prevent gusts going under the board and launching you! Especially on wide arse boards like mine.
I typically roll the foil more to windward if getting too much lift, and use the back foot to roll the board flatter if I'm riding too low. These movements can be smaller and more subtle than stomping on the back foot to get up.

Out of Control ?
Finally, what do you do if you're out of control? If your harness is set just right, hopefully you can unhook with a quick tilt of the hips. People often say "Don't let go!" and I tend to agree, especially if airborn backwards, you can more easily land on the foils. I've catapulted forward and looked up just as my board - still foiling - came straight at me.

If you have time, stomp on the windward rail, hard, and roll to windward as fast as possible, angling the foil will reduce lift and if you do breach hopefully you fall backwards instead.

PULL DOWN hard and fast on the boom to drop the foil can sometimes work..

WOBBLE BOARD can also help, as changing the foils angle quickly reduces lift.

The biggest problem as far as I have experienced is that when you get out of control I typically sheet out and even then, I don't slow down so the foil still has too much lift, and now I have less downforce.

Accelerate Slowly... avoid rapid acceleration as you may find yourself out-lifted before you know it!













Nice post Berowne

I'd like to ad something about the harness, please correct me if I'm wrong, but the seat harness, once you are powered UP, starts pulling you upwards, removing presure on your front foot, specially if the boom is very high.

This was great with fins, because you remove weight from the board and transfer it to the sail, so the displacement of water at speed was lower, so, faster, but in foil is diferent, because that weight is your control tool.

To keep weight in your feet at high load try a waist harness (I used to hate it, but it worked for me). I came from formula so I was a "seat harness evangelist", but I made the change and I have to say it was for the better.

Hope my english isn't that bad and my tip help someone

Cheers!

bul131
11 posts
25 Sep 2021 2:41PM
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Hello Please explain to me what the difference is between fuselages 115 and 115+ because I only have to get one and I don't know which one to choose. who gives what to the ride.

Tony Polony
NSW, 337 posts
25 Sep 2021 6:56PM
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I don't have a great deal of experience in the foiling scene but can tell you that the "+" model has a number of pre-formed shims that will adjust the pitch of the stabiliser for varying wind conditions. I would recommend the "+" fuselage for this reason.

berowne
NSW, 1210 posts
25 Sep 2021 9:50PM
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bul131 said..
Hello Please explain to me what the difference is between fuselages 115 and 115+ because I only have to get one and I don't know which one to choose. who gives what to the ride.


BUL131, the 115 and 115+ are almost identical. The shims work on both. The difference is per the photo above, on the left hand side of the tape measure, the plus moves the front wing +10cm forward.
This is essential to be competitive in upwind/downwind course racing with big sails but makes slalom style reaching harder.

Bellerophon
65 posts
25 Sep 2021 10:33PM
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berowne said..

bul131 said..
Hello Please explain to me what the difference is between fuselages 115 and 115+ because I only have to get one and I don't know which one to choose. who gives what to the ride.



BUL131, the 115 and 115+ are almost identical. The shims work on both. The difference is per the photo above, on the left hand side of the tape measure, the plus moves the front wing +10cm forward.
This is essential to be competitive in upwind/downwind course racing with big sails but makes slalom style reaching harder.


To use the shims on an normal "black" fuselage, you'll have to do quite some machining to make the shims fit.

Subsonic
WA, 2964 posts
25 Sep 2021 11:20PM
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Bellerophon said..


berowne said..



bul131 said..
Hello Please explain to me what the difference is between fuselages 115 and 115+ because I only have to get one and I don't know which one to choose. who gives what to the ride.





BUL131, the 115 and 115+ are almost identical. The shims work on both. The difference is per the photo above, on the left hand side of the tape measure, the plus moves the front wing +10cm forward.
This is essential to be competitive in upwind/downwind course racing with big sails but makes slalom style reaching harder.




To use the shims on an normal "black" fuselage, you'll have to do quite some machining to make the shims fit.



I'll hazard a guess you're referring to a starboard foil. No machining necessary to make shims fit an F4 foil.

you can actually make your own shims to fit if youve got $5 and a bunnings hardware nearby (ok, you'll need a set of scissors too). But from berownes' f4 review, looks like they come with ready made shims now.

LeeD
3939 posts
26 Sep 2021 2:43AM
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JB083...
Can you lower the boom, seat harness, to ADD more weight on your front foot?
Or is it necessary to hang DOWN on your harness to add weight to the boom and mast track?
Or can a more twisty rigged sail dump some unneeded wind, so you can stay sheeted in?

berowne
NSW, 1210 posts
26 Sep 2021 12:01PM
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I'm finding leaning board more to control foil lift is working and leave sail trim for sail control. Of course there is still a lot of control through the harness but subtle foot control helps to keep board ride hight where I want it.

jr555se
5 posts
26 Sep 2021 8:52PM
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berowne said..
945 (1000) front wing, 210, 230cm rear wings, 115+cm Fueslage

"Move the mast base forward when overpowered" they said. Makes sense, but I have a warning, Hell NO!

Interesting update on the Big Race Gear. I rigged the big wing with 210cm rear and small shim, hittting 22.4 which is a new PB on this wing for me. I then hit a half hour lull and changed to the 230cm rear wing with NO SHIM just to see if it would lift better in the light winds. But being an offshore westerly, as soon as I got a few hundred metres off the beach, the wind built to over 20kts gusts.

However, unlike the first time I used this setup it was stable and controllable, as long as I could keep the 10.0 sheeted in! The upwind angles felt intense and controlled, VMG attack mode (just a shame I didn't have a training buddy). Without the shim I was even comfortable sending it downwind, maybe 1kt slower than the 210 rear wing. The back foot especially felt really strong underfoot and the wings responded to roll angle very well.

Then for a comparison, I set the mast forward 1cm to 136. While I could ride like this in stable winds, but the gusts were nearly impossible to control. Pitch response was violent and scary and after a few runs I gave up trying to tame a wild beast. Feeling like a challenge I then set the mast-base further aft, to 134 and again it was sailable but hard to control and got high a few times.

Setting the mast-base back to 135 again, and control returned. I was amazed at how sensitive this big wing was to mast base setting, but super impressed with the performance when setup right. I then did a few downwind gybes and leaning forward over the foil I could feel the balance point easily and carve the board around with a light sail. The sail flip was sublime... Lean into the turn, open early, shift sail outboard, rearwards and flip, drag forward, pop and go... wow just sublime!

In conclusion, the F4 big wing race set is fast, but super sensitive to mast base position!






Nice read about your tuning progress.Trying to relate but since on a different board, its abit hard. I wonder what is the distance from the front screw of the foil to the 135 mark on your board?
-jr555se

BluntWhite
9 posts
26 Sep 2021 10:01PM
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Thank you! Berowne, photo of the various fuse lengths relative to the fin box with a measure was really excellent!

Photo of the mast base on the board suggests you're measuring mast base location from the tail and not the front fin screw (using the photo of the fuses, I subtract 24cm +/- to convert to "front screw notation").

Please comment on your weight distribution between front and rear feet (in percentages). I've been on F4 foils since 2019.

Thank you
Blunt White
Stonington CT USA

berowne
NSW, 1210 posts
28 Sep 2021 7:48PM
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F4 setup tips

berowne
NSW, 1210 posts
28 Sep 2021 7:54PM
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BluntWhite said..
Thank you! Berowne, photo of the various fuse lengths relative to the fin box with a measure was really excellent!

Photo of the mast base on the board suggests you're measuring mast base location from the tail and not the front fin screw (using the photo of the fuses, I subtract 24cm +/- to convert to "front screw notation").

Please comment on your weight distribution between front and rear feet (in percentages). I've been on F4 foils since 2019.

Thank you
Blunt White
Stonington CT USA


Hey Blunt thanks for posting. I generally ride front foot heavy maybe 60/40 but react as needed. If I need more I try to hang off the harness or angle the foil to depower the wing and cut the lift
I did find the 90 fuselage needed about 30/70 the other way rear foot heavy until it wasn't.

jr555se
5 posts
29 Sep 2021 5:05AM
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So by looking at the photo it gives me about 1-2cm margin of err. Which is about the same amount that gives an decently balanced to abit handful in the gusts you explained it well.
I would really appreciate if you can find time to measure from the screw where youre at, even though all sailors are different.

115+ lightwind race 1000 wing and 230 stab, no shim. rake 2.5
So here are my measurements from hgo 9.0 in a very gusty 7knots to 17knots which are given the margin of error quite on the same spot as you Berowne.
mastfoot 110cm, being on 109 keeping the nose down was abit of a struggle. measured from the front screw
Still not balanced though.. Maybe you have tried already but moving harness back into front hand pull for me actually helps but I will play more with that and boom height next session.
My boom is quite low at mid position of the sail(if you're not on hgo which I think you are not that may not help much in your quest) I find that better than high boom for some odd reason. Considering I always ran highest possible before.
I am 197cm 90-100kg and still much slower than you so not to be used as a reference but more for data comparison.

Front foot straps center at 58cm from front screw.
Back foot parallell to the front screw, sometimes abit behind if lighter.

berowne
NSW, 1210 posts
29 Sep 2021 1:00PM
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I used a few vertical props since the back of the board is very thick and rounded, and the front screw quite deep in the well...
Distance from rear of FMX to front-screw of finbox is 22cm

jr555se
5 posts
1 Oct 2021 5:09AM
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berowne said..
I used a few vertical props since the back of the board is very thick and rounded, and the front screw quite deep in the well...
Distance from rear of FMX to front-screw of finbox is 22cm


Thank you!
Your mastfoot is then much further forward than mine. I moved the boom higher today an inch from where I am used to ride and mastfoot forward. It wasn't flying out of control but I had a hard time getting the sail stable in the gusts. Broke my PB on the F4 today after that :)
Since I only have the lightwind setup I am gonna keep pushing and see how fast it can get with me onboard. still far from even 25 knots

berowne
NSW, 1210 posts
5 Oct 2021 8:58PM
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JR, sounds like you need to spend a little more time coming in and out of the beach. Moving the mast a cm or even half can be really helpful. I changed mast positions 3 or 4 times in one session to feel the difference. And added the 1cm marks on the mast track so I can get the measurements more accurate.

Having the right sail for the conditions also helps. I am often too stubborn if I set up a rig I'm reluctant to beach it and change but I'm learning that too much sail is slow because you can't get in front of it" and sheet in with the harness but instead just sheet in enough to hold the wind.
Yesterday it took a small break to add a 0.5mm shim and the wind to drop a few knots. Then I could really sheet in on a reach ame practice figure 8 slalom runs. Good times.

berowne
NSW, 1210 posts
9 Oct 2021 10:37AM
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Good session on 560, 100, 190 combo with small 0.5 shim yesterday. Pushed it to 27.5 VMax now with the mast base right back at 130cm 5.5m sail was too small in the holes, which were very hollow up near the runway but the smooth water for over 2km runs was a great place to push.
The small slalom sail was just manageable on the gusts, so glad I didn't go larger for the speed runs, but I needed larger for most of the reaches. Unfortunately my high clew fitting did t work on this sail and the ropes kept popping off so had to settle for the low slalom boom/clew setup which made the sail a bit twitchy.
Chasing the raining state slalom champion on a chopper fin and 7.7m sail was inspiring, but Remi had me beaten every run except the upwind 7k commute where the upwind power of a 97cm foil mast has a VMG advantage over 42(?)cm fin.

timbat
ACT, 43 posts
10 Oct 2021 10:24AM
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berowne said..
Good session on 560, 100, 190 combo with small 0.5 shim yesterday. Pushed it to 27.5 VMax now with the mast base right back at 130cm 5.5m sail was too small in the holes, which were very hollow up near the runway but the smooth water for over 2km runs was a great place to push.
The small slalom sail was just manageable on the gusts, so glad I didn't go larger for the speed runs, but I needed larger for most of the reaches. Unfortunately my high clew fitting did t work on this sail and the ropes kept popping off so had to settle for the low slalom boom/clew setup which made the sail a bit twitchy.
Chasing the raining state slalom champion on a chopper fin and 7.7m sail was inspiring, but Remi had me beaten every run except the upwind 7k commute where the upwind power of a 97cm foil mast has a VMG advantage over 42(?)cm fin.


Wondered what sail size you were on!

berowne
NSW, 1210 posts
10 Oct 2021 5:38PM
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No 30 Knot runs yesterday... but a good training session with raining world (OK NSW state) slalom champion Remi on his frighteningly fast slalom kit.

Paducah
2451 posts
10 Oct 2021 10:19PM
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Berowne, loved the comments.

Bellerophon
65 posts
11 Oct 2021 4:28AM
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Some free tips from a fellow Hyperion rider.

- your harness lines seem rather short, esp given the light conditions. Better get way back from the boom.
- there's NO WAY he should be able to pass above you. When you hear him comming , start pointing upwind
- once you master the flyiing jibe, in these (marginal slalom) conditions, you should always be able to stay in front .. (even after jibing around him )

Good luck !

thedoor
2191 posts
11 Oct 2021 8:11AM
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Bellerophon said..
Some free tips from a fellow Hyperion rider.

- your harness lines seem rather short, esp given the light conditions. Better get way back from the boom.
- there's NO WAY he should be able to pass above you. When you hear him comming , start pointing upwind
- once you master the flyiing jibe, in these (marginal slalom) conditions, you should always be able to stay in front .. (even after jibing around him )

Good luck !


stay upwind to give them dirty air?

berowne
NSW, 1210 posts
11 Oct 2021 11:36PM
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Bellerophon said..
Some free tips from a fellow Hyperion rider.

- your harness lines seem rather short, esp given the light conditions. Better get way back from the boom.
- there's NO WAY he should be able to pass above you. When you hear him comming , start pointing upwind
- once you master the flyiing jibe, in these (marginal slalom) conditions, you should always be able to stay in front .. (even after jibing around him )

Good luck !


Thanks Bellerophon! I definitely need to keep more speed through the gybes. I find it harder to keep the small wing flying the whole way around. When I do get out on the race wings they seem so floaty!

I don't have trouble pointing on the slalom runs. If anything, I'm finding it harder to push on a mildly broad reach, say 100? to 120? And so I was trying to follow Remi's lines.
Bellerophon, how open/deep do you set you footstraps? I find I like having the rear foot especially deep so my toes are closer to the centreline.

lhtrindade
21 posts
11 Oct 2021 9:38PM
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Hi Berowne,

Nice post, lots of useful information.

Here I have been sailing on a big race kit, my top speed was 28kts with 0.5 shims, using GA Vapor AIR 9.1 and Tabou AIRRIDE+.

I changed to 1.0 shims, but couldn`t try top speed because my last session had some swell.

I don`t know if I missed anything, but do you have been checking the rake of the foil mast? I have been sailing with 1,5 and with some swell was very hard to do some downwind legs...yesterday I changed to 2.0-1.8 and changed a lot the feeling of the board on the downwind.

Also, just changing how much downhaul you put on the sail changed a loooot the balance of the foil.

John340
QLD, 3047 posts
12 Oct 2021 7:04AM
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Great video, drag races are so much fun. I love the bucket hat under the helmet. The combined effect looks like a German WW2 infantry helmet, cool.

Freeflight
111 posts
12 Oct 2021 6:23AM
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lhtrindade said..
Hi Berowne,

Nice post, lots of useful information.

Here I have been sailing on a big race kit, my top speed was 28kts with 0.5 shims, using GA Vapor AIR 9.1 and Tabou AIRRIDE+.

I changed to 1.0 shims, but couldn`t try top speed because my last session had some swell.

I don`t know if I missed anything, but do you have been checking the rake of the foil mast? I have been sailing with 1,5 and with some swell was very hard to do some downwind legs...yesterday I changed to 2.0-1.8 and changed a lot the feeling of the board on the downwind.

Also, just changing how much downhaul you put on the sail changed a loooot the balance of the foil.


This F4 sounds exciting, did you use 115 or 115plus for your top speed 28 with 9.1m sail



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"F4Foils Tuning Tips - Towards 30 knots!" started by berowne