Short video here from F4 with a bit of info on wings currently available in the range

Have been using the 2021 course race set for about a year. I'm noticing similar stress cracks on the mast-fuselage connection, even though everything is firmly set, with screws in place. Haven't crashed into anything with the wings, and it appears as if the back-and-forth twisting force from the fuselage and wings is causing them, since they're appearing at both ends of the mast. Thinking of contacting F4 about it, especially since it seems to be a common problem.

regal1 said..
I twice had the black bog filler fairing come off from the front of the mast at the fuse join. The missing bog measured 2 cm x 2mm wide by 0.5mm deep down each side. Nothing stuck as it got torqued off. The advice from Chris R at F4 was to sand it fair. Seems like a design problem as I haven't seen another brand's mast do that. It only happened at the front of my mast & not the rear like yours. My set was mid '21 from Sonic Composites in China. I understand that production moved to Europe this year so perhaps it's been fixed.

Yup, it does sound like the same issue - think we have the same batch from Sonic. Will try to get photos later this week. I notice some occasional creaking when gybing under strong load (big sail, big wing), but other than that the stability and performance is really top notch. All I worry about is losing the entire fuselage and wing set when the stress fractures cause the entire thing to give way one day. While I don't expect a brand new mast to come for free from F4, it's certainly making me think whether I should order another mast/foil set, or just switch to another brand entirely.

regal1 said..
F4 were quite sanguine about it. I've owned an iqfoil set & the 2019 Phantom 1st gen (all manufactured by Sonic) and they all had the same black bog with silver fleck finish on top of the carbon. I found the bog is soft & scratches easily. The crack wasn't in the carbon layer so I never worried about losing the fuse. I switched to another brand but that was also about unavailability of individual F4 wings last year. My F4 masts were very stiff.

Not to detract from the topic, but what did you end up switching to? I'm thinking of keeping the F4 set at least for the rest of the year, till the 2023 foil designs are out. Similarly, how did you feel the Phantom 2019 set compared to the F4?

I wanted to go fast so I bought what the world champion used and found the first gen 2019 phantom very, very hard for me to sail in a straight line let alone go fast. I constantly felt out of control. I found it hard to get going then once I got going, I was quick to fall off the foil. By comparison, the easiest most docile foil to sail was an IQ foil set while I would rank the F4 & Sabfoil course racing sets as very similar to each other and sweet to sail but both have more lift/power and are easier to gybe than the iq. They don't give any surprises or unexpected moments and both give notice of breaching then settle down quickly. In comparison, I found the 2021 lokefoil & 2021 Boss 5.0 foil much trickier to sail than SAB or F4. Sabfoil have a very good Australian distributor who has had ample inventory and the small wings on the slalom fuse are a joy to ride. Now SAB have introduced a new stiffer, thinner mast (Kraken) but with a different deep tuttle attachment (which appears to make mast rake difficult to adjust) so the old mast & fuselages are superseded. Lokefoil's 22 range was completely new with nothing interchangeable with the 21 range. So, after all that I'm going to give the gen 2 phantom a crack. According to Alex Udin, the foils are made by a new Cobra (!) division run by Jean Jacques Deboichet and have a much tighter production tolerance then Sonic with better shaped foils that are easier to sail but faster. The AUD euro rate of 0.70 helps. Phantom's policy is to have the same set for 2 years so in April 23, I shouldn't feel like I've set fire to wallet. Having said that, I'm keeping the 2021 Lokefoil set as it's quite challenging and rewarding to sail & the foil, mast & fuse finish is extremely tough. I promise to write a review but I have no idea when I will get the set.

regal1 said..
I wanted to go fast so I bought what the world champion used and found the first gen 2019 phantom very, very hard for me to sail in a straight line let alone go fast. I constantly felt out of control. I found it hard to get going then once I got going, I was quick to fall off the foil. By comparison, the easiest most docile foil to sail was an IQ foil set while I would rank the F4 & Sabfoil course racing sets as very similar to each other and sweet to sail but both have more lift/power and are easier to gybe than the iq. They don't give any surprises or unexpected moments and both give notice of breaching then settle down quickly. In comparison, I found the 2021 lokefoil & 2021 Boss 5.0 foil much trickier to sail than SAB or F4. Sabfoil have a very good Australian distributor who has had ample inventory and the small wings on the slalom fuse are a joy to ride. Now SAB have introduced a new stiffer, thinner mast (Kraken) but with a different deep tuttle attachment (which appears to make mast rake difficult to adjust) so the old mast & fuselages are superseded. Lokefoil's 22 range was completely new with nothing interchangeable with the 21 range. So, after all that I'm going to give the gen 2 phantom a crack. According to Alex Udin, the foils are made by a new Cobra (!) division run by Jean Jacques Deboichet and have a much tighter production tolerance then Sonic with better shaped foils that are easier to sail but faster. The AUD euro rate of 0.70 helps. Phantom's policy is to have the same set for 2 years so in April 23, I shouldn't feel like I've set fire to wallet. Having said that, I'm keeping the 2021 Lokefoil set as it's quite challenging and rewarding to sail & the foil, mast & fuse finish is extremely tough. I promise to write a review but I have no idea when I will get the set.

It is disappointing to see the flaws in manufacturing and design. Especially the ones from F4 or lets say Sonic manufacturing. You might want to make sure that a new line will be released in 2023. My understanding is that they might extent the 2 year guarantee and it could be 2024. I would also like to get some feedback on the 21/22 X and R mast that are both made at the Cobra factory. Does anyone have experience with those mast and connection to fuse?

Above are F4 supplied foil box foil printed mast shims. I couldn't work out why the mast rake angle changed materially after one sail until I dug it out. This is a minor issue but it shows a lack of care. The shim material compresses far too readily. I also found the thin rear shims broke easily. Maybe it's changed in the new sets. I haven't had this happen to Phantom/Goyard 3D printed shims.

No, I didn't have to change my mast screws. They should have changed to less compressible material by now.

The shims I like are from ap3dcustom.com. Much tougher than the F4 supplied shims. Excellent carry case.

If you can crush the shim with linesman pliers then they're the same material which imo isn't satisfactory.

About 14 months now since I switched from NP Freeride foil on to the F4 2021 series foils
My F4 has been worked hard clocking up thousands of k's while enjoying great reliability and exhilarating riding
We have great little network of riders on F4 in Australia sharing tips
Recently I was lucky enough get some drone footage, big thank you goes to local sailors Michael and George
Footage riding F4 Slalom 'Large' 100cm fuse / 620cm2 wing
Enjoy!

Kasper79 said..
My local supplier\sponsor and good friend are working on some shims for the F4 foils. I have tested it once and it seems more stable then the originals f4 shims as the load has a bigger surface to be displaced on. Went on to a new to a new pb on 5x10 on the first run with the shim so pretty excited. I used the 700(560) front wing and a 7,7 Avanti machine, not fully powered, so hoping to get over 30 knots next time.

Congrats on the new PB Kasper

The new shim design looks good, they won't point load the bottom of the board foil box, i have been using a self made system of the same design
Cheers
TK

Update: the mast-fuse connection finally gave way, and the rear fuse bolt/screw section (towards the stabilizer, so the third one) has begun to come apart, just below where the original cracking occured. Had to order a new mast, out of a fear of losing the entire fuse when under load.To clarify, the fuselage is entirely undamaged, it's the mast that appears to be damaged or defective.

The thing that surprises me the most is my top speeds on different foils... 26kt +/- 1.5knots on race to slalom foils.

I've still got a lot of work to do to be able to push past 30kts more often! Just the one run above 30.. and I've only had about 3 rides on the 420 but I think it will be a better option than the 337 for everything except maybe Defi!

You're right, I don't want to crush the top of the tuttle box. However the supplied F4 shim material is so soft, that was never going to happen. But I want my foil mast to be raked back. The APD and Goyard/Phantom shims work fine. Denser, stronger material and no damage to the tuttle box.