F4Foils Tuning Tips - Towards 30 knots!

You must be getting good at maintaining the mast base pressure with your boom during a gust. It's a good skill to develop. Normally when a sail sheets out, the MBP decreases, which can result in a foil out.

Good session at 28kts yesterday on 660 and formula setup. Admitadly the 660 is a bit small for a 'formula' foil but I like the control!

I sailed from Kurnell up to Kyeemagh.
F4 660cm2 850 wide with 190cm2 tail and powerful 115+10 fuselage. No Shims, 2 degree rake.
CHS 9.1 sail - right size but some gusts were big!
Patrik v2 100cm was nice and wide to help control the gusts

Learning to stay committed with gusts and ironically, how to not accelerate. This means I can stay closer to 100% without going over the front!

Also reaffirming how important it is to have excess front foil power... you need to have excess lift so when you are dipping down, the movement to a level board gets the nose up immediately to help avoid nose diving.

I find the 660 works well on the 115+10 or 100 fuselage with -1 degree power shim. I might oneday get to shim a little more for even more power,... but not yet! I was riding a little back-foot heavy around 20-25 knots but definately front foot heavy at peak speeds.

New fastest 2s speed by 1knot for 9.0/9.1/10.0 and on 660 is also 1kt faster than other formula setups for NM.

gpsteamchallenge.com.au/sailor_session/show?date=2023-04-15&team=33

SLOWING DOWN SAFELY is hard!

I think this is THE main problem with foiling! Going 'too' fast and having no easy way to slow down...

Some thoughts on this, summarising 5 odd pages:
Going fast is fun... until it isn't
Things go wrong VERY quickly
OHH **** MOMENT: Push back hand away, while sitting 100% weight into harness (requires long lines), pulling IN with the front hand to de-power, stomp on windward rail (even back foot!) and try to get the windward rail down... you might even touch the water, but hopefully slowed down and 'low-side' crash instead of going over. I did this (half by accident) a few weeks ago and broke a foot batten :(.
Alternative is to turn downwind, as far as 180 degrees, but this involves levelling the board off, and potentially increasing lift.
Another Alternative is to pull down hard on both hands, sail still sheeted in, drop your hips and pivot to release the harness without dropping MBP, so your'e not hooked in when you go over... but this action might help you go over... :(
If you have time to move the back foot out of the straps then sure, you can get more weight forwards.

If you have lines a little bit forward, it is easier to sit your weight in the lines, sheet in with the front hand to 'apply the brakes' and NOT accelerate in a gust. I find that downwind runs are better with some degree of sail-on pressure, rather than fully feathering the rig.

Open to other ideas :)

I had my first slalom ride a few days ago in months! I've been too focused on Formula riding lately. The conditions:
I had an ideal mid-week day off with 20-25 Kt SE and very flat water in George's River, Botany Bay Sydney. Rigged a smallish 6.1m CHS Foil sail that was a touch small in some 15kt lulls but perfect for the day and plugged it into my 91 FMX Hyperion at 130cm. I like the width on small wings because I need the rail leverage and 75 is too narrow for my style!
Next I selected my F4 101 mast at about 2? rake (need more!) 100+3 fuselage, 400 front wing and 190 rear set at -1? for a bit more power.
The first few runs were warm ups but after a couple I settled in for a bear away and got overpowered, catapulted, rolled mid-air and skimmed along the surface gazing at the clouds.
Came in and removed the power shim and felt like I didn't have enough lift. Without moving the mast I tapped down mid gybe and sheeting in drove me down and the board felt sticky.
I came back to the car for my -0.5? and this seemed to be the sweet spot. It is surprising how much difference these small changes can make. With the right setup I hit 29kts (Coros watch) and to be honest I was too scared to fully commit and go faster! The power from this tiny wing is addictive but riding fast is really another level of concentration and commitment with even small swells giving you a moment of doubt about why your half a metre above the water at 55+km/h!!??

"Send-It"!!!!!!

WOW WHAT A RUSH!

That was an awesome day!

Still buzzing!
F4 400 100+3 190 no shim
CHS 6.1 Foil sail
FMX 91 @ 136cm mast

I went out to Kyeemagh, after work for a great afternoon N/E (lacking the sunshine). I rigged my F4 400 foil on 100+3cm fuselage and 190 rear wing with no shim. The foils had all been recently puttied up and sanded to 2000 grit so this might have helped...!?
The foil slotted into my trusty FMX 91cm Hyperion board, at the standard 130 setting that proved ohhh so wrong for this foil!
I chose to go with the CHS 6.1m foil sail instead of Patrick cross-over 5m as it is a much better foiling sail, and glad I did, although initially I really wanted to change down to a 4.5m!

Peaking at 30kt gusts the wind was on! I was totally out of control for the first few runs with the mast-base at 130cm so I moved it +5cm forward (remember I usually say to move it 0.5 to 1cm!) and felt in more control, managing a 30.30 run, with 'some' control...

I had a break on the beach chatting with a few friends, added another +1cm more mast base and by the time I went back out with Jules the wind had dropped back a few knots too.

And now it was on!

After a few runs with Jules, we lined up next to each other and as I sailed past under 4m away I yelled out "Send IT!" and turned downwind... accelerating... accelerating... accelerating and just kept going... The sail was taught on the outhaul and well trimmed, feet pushing down on the rail, but also a bit forward urging the board straight ahead rather than just fighting sideways.... and the trim was awesome, no touchdowns, riding smooth, fast, and I felt ... well scared, sure,... but actually enjoying the thrill and knowing I was on the edge, but IN CONTROL! WOW!

What a setup, FMX, F4 and CHS are a great combination!
Track Details (ka72.com) www.ka72.com/Track/t/521302

Looking at the images, it seems the best speeds were actually AWAY from the runway!
So many PB's and just great achievements! 32knot 2s peak AND 100m, 30kt 500m, 30knot 5x10s, 21kt alpha,
Thanks Jules for the celebratory dinner!

This thread got me interested so I watched a few of the F4 YouTube videos on speed and tuning yesterday. I found them quite informative. This one could be helpful for people not in the know.

30 knots is so 2023!

Another big session today!
NE 15-20kt gusting to 25. Really quite gusty and oh the jelly fish!

I'm really starting to get the hang of this 400 front wing... it is powerful and stable at slow speeds, with confidence to push at top speed.

Today, I did something I've been trying to do for a decade... beat Remi! He was on 8.4 large slalom gear vs. me on 7.1m and small foil but hey... he is da man to beat!

* F4 400 190 100 +0 Fuselage this time (+3 last time), but still had to have the mast base just back a touch around 137 or 138 nearly all the way forward. Probably need a depower shim to be honest!
* The FMX 91 Hyperion was stable as always!
* CHS 7.1 Foil sail with a LOT of downhaul - actually a touch too much for a while as it was too twitchy so I dropped 5mm later.


Good setup, but the wind was a bit light sometimes, but then the big gusts hit and they were mostly controlled.


FARKING JELLY FISH EVERYWHERE! Dropped one gybe by the single celled brains... and 1 catapult directly caused by them too, along with a whole bunch of stalled flights... mostly dry! Also, another catapult at speed, back landed and whiplashed my neck. I think I'll get one of those neck braces Michele Becker wears.

2x PBs today...
Measure Result

2 Second Peak (kts):32.429
500m31.536
5x10 Average (kts):30.584
Alpha 500 (kts):21.337
Nautical Mile (kts):28.162
100m peak (kts):32.127
Total Distance (km):45.845


What works for me... well lots per this very very long thread!
* 5 years of ToW about once a week, 3 times a month or there about.
* Attention to settings. Today I dropped the boom, moved the mast twice, changed the shim angle, changed the fuselage, changed the downhaul twice, changed harness line length, .... all to get in the groove.
* Progressive improvement... I've been working on building up my cruising speeds so I am more used to 20, 25, 27, 28 knots. This way 30 knots isn't too unfamiliar. (Nico Prien had a wiggly up-sloping sine wave describing this, work on lifting your minimum speeds each session, then the max will improve too).
* Intuitively knowing how to trim the board. See ToW. My 31kt 500m run was SOO FAR FROM STABLE but I dare say the board and sail would have looked pretty much stationary... except my body and pressure points were moving massively. Exactly how is hard to describe but it all depended on what was happening... if I was dipping down (flatten board angle, back foot toe pressure, body weight back a touch, not to much!), nose high (front and back foot heel angle.. back foot pushing body weight forward (against the rear of the foot strap) so the harness pressure was more forward, maybe backhand ON to push sail down too) lean further outboard, turn downwind, adapting to chop... etc
* Willingness to crash. Sometimes the edge pushes back. Sometimes slowing down is hard, sheeting out is dangerous!
* Sail where the wind is! Fastest run was definitely away from the runway giving the wind time to get down to my level, and DEEP, about 145 degrees off the wind, maybe would have been faster at 135 but I didn't need any more pressure !


Foiling fast is very technical, and I get that it is not for everyone... about half a year ago I was struggling with motivation and backed off a bit, spending more time on Formula gear (outside iQ - damn that sport is dying!) where 25kts feels sketchy!. But I dare say that Winging above 20kts is also technical and risky. But the wipeouts seem to be less extreme!

Anyway, it's a fun journey, and feels pretty nice to be within 1 kt of the local fin sailors speeds, that gap feels achievable!


BUT if my past experience with fin sailing and chasing 40kts is anything to go by I know that every single knot is hard fought and exponentially harder, often requiring new gear or talent to unlock!

Hi Georgio... can't agree more... time for an upgrade!!!
F4 just released a new batch for the PWA 2024 and so my current foils are up for grabs...


www.seabreeze.com.au/Classifieds/Windsurfing-Foils-and-Foil-boards/~mbm1g/2022-F4-Foils-Slalom-And-Course-Racing-Ca-Foils-And-Se-101-cm.aspx

Yes F4 GP Wahoo!