I read this too, but the mast fuselage interface can barely be fitted, it’s as good as it can get with the Gong design. Only way to get it stiffer is to do a permanent joint with a composite overlay or reinforcement clamping plates.
I can break it. 100 cm wing on top of a 65 cm thin alu extrusion, with that kind of leverage it doesn’t have to be tried.
You can snap a Carbon mast with that easily too. Every carbon mast i have ridden has had more flex than the Aluminium masts. They just done stay bent after flexing.
This is what you need to fix though. I have ridden the Unifoil wings with both Axis and Gong masts and didn’t notice any difference because the adaptors I made were so tight and had absolutely no play. The best option would be to do a better fuselage like the axis where it also slots up the mast so isn’t just relying on tension from the bolts.
That’s interesting. Are you comparing same dimensions? 13mm Gong vs 13mm axis will naturally be close in side bending as long as the profiles have roughly same section.
beam stiffness is a function of width^3, a square beam example at 19^3/13^3 would be 3x stiffer all else being equal. I bet you already know this but what i mean is that standing with 130kg on a mast connected to 100cm wing stresses that extrusion a lot. If i could carve a tight turn (i don’t, yet )then i bet it would be noticeable to go to an axis 19mm mast.
The gong parts should have a tapered interface, that would make the it as good as it could be.
Yes, the Axis would be stiffer simply because of its extra width, but what I am saying is that I (90Kg) have done some tight carves with the Unifoil hyper 210 wing and not noticed any flex in the gong mast with 100% solid mast to fuselage connection. This is my adaptor:
As you can see it runs up the mast and then also wedges into the fuselage. Thus eliminating any play.
If you are in the 130Kg region though, then I would suggest the Axis mast. It’s pricier but when you have it in hand you will understand why. I have slingshot, Gong and axis. I use the gong for efoil because it’s thinner and has less drag. The Axis mast is used for wake and surf (my brother uses it too and he is around 115kg) and the slingshot now just suffers from dry rot.
that’s the tapered interface right there, like it!
Does the positioning of the CF rods or tubes matter? Is it better to have them at the extremities or in the center slot?
I’d say center slot since the open profile is larger there. You can think of them as trusses.
Edit: just realized that this was discussed quite a bit above but I think it can still be expanded a bit.!!
That’s what I’ll do but then I’m wondering. Does the flexibility of foil comes from the modular connections (mast plate to mast and mast to fuselage) or does it actually come from the mast flexibility (mast alone)? I know this point was mentioned above but I’d like to expand on it. Does an aluminum mast have some flexibility or does it just bend under some force and doesn’t go back to normal? @Jezza any thoughts? If the alu mast doesn’t have much flexibility, that means it may not be optimal to reinforce it on full length to improve its stiffness and my efforts should be shifted to stiffening up those modular connections. Has anyone tried to weld the mast plate to the mast? I feel that’s where most of my flexibility comes from in my setup (already have slots adaptor for different wings).
There will be some flex in an alu mast, but it’s not going to be that much and most people would never ever notice it. It would be more likely that you’d bend the mast.
The flex at the bolt joins is the most likely candidate if the mast and fuselage don’t taper and slot in properly. It’s a slower flex than if your wing is loose which feels more like a flutter/twitch.
My very first adaptor I made was a simple piece that never went into the mast and just relied on the bolts. You would even feel slight worming on the foil as the connection twisted ever so slightly. Now I only use adaptors that run back up the mast and slot in properly.
Aluminium has a yield point just as steel does, especially the 6061-t6 that i think the masts are made of so it has flex. But probably jezza is right that a large part can come from gaps in fuselage and mast connection.
I’ll try before and after glueing these solid (during winter building). That’ll show if there’s a worthwile improvement for my gong mast
The AXIS tech team, claims that the AXIS 19mm Aluminium mast is 224% stiffer than the oem LF mast.
On the other hand, the AXIS 16mm Aluminium mast is 135% stiffer than the oem LF mast according to the same study.
The AXIS 19mm Aluminium 75cm mast is only $108 US and very well suited for eFoils.
I am working on a new built with the 105cm 19mm AXIS mast which is a beast.
At this low price, why bother with anything less that won’t be as stiff anyway?
Does the 16mm mast have the same profile and segment as the 19mm? What do you hope to gain from the 105cm? I’m kinda curious to try it!
About the masts, the 16mm is obviously thinner - so a bit less drag, a bit faster / more slippery.
About the 105cm, with the motor, you loose a bit of a mast height. And the higher you ride on the foil the more efficient / less drag. Also better carving / edging with the longer mast.
If you have the water depth it’s the way to go imo.
Agree for carving, also helps with swell but for drag it’s not the absolut length of the mast but how much of it is left in the water, so a short mast can have the same drag with the same part in the water as a long one. A longer mast also tends more to flex as there are higher forces due to the longer lever. A longer mast needs to be more robust, which adds weight. Might also be more difficult to ride, so it depends where you use it and is also a matter of personal preference.
Well said - all of the above. I love riding higher on my foil, so for sure a personal preference.
The 19mm 105cm mast is a beast. I have been riding it for winging, kite foiling and friends ride it windsurfing foiling (which puts the most torque on the masts). No issues. It’s the stiffest mast on the market. Can’t wait to eFoil it when ready
You’ll probably have the longest efoil mast in the world haha! That has a nice ring to it! Please report back once you ride it a couple times! We need a 90cm - 105cm comparison!
How much drag would you say the 19mm has over a 13.5mm mast? How does it affect the riding experience, speed and efficiency?
Drag is directly proportional to frontal area so at 19/13mm it’s 46% higher drag for the bigger mast. I guess this is still small effect compared to many wings though.
Must be someone (like jezza) who has run both types with same wing?
A 13.5mm is not suitable for eFoiing.
That’s what 90%+ of the people on the forum have been using with success (and some failures but mostly success). I wouldn’t say it is not suitable for efoiling because it obviously works! Is it ideal or the best? Probably not! That’s why I’m curious to hear more about how a 19mm mast rides through the water compared to much thinner mast that cut through the water!
