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 fueslageI'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 SetupTo 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 downThe 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!