Same fuse length, different foil behaviour: the forgotten mast-to-FW distance

This topic has already sparked a few debates. To me, mast-to-front-wing (while keeping the overall fuse length identical) still feels like one of those hidden tuning parameters that everyone indirectly talks about, but very few people actually isolate and test properly, and the answers are often contradictory. So here are my views after few recent experiments.

It’s not that no brand allows you to play with it. Axis actually does, in a way, through the different Black / Advance / Advance+ / Advance 20 fuselage families.
The tricky part I found is that these options usually come with strong product positioning: Advance+ being marketed more toward performance and advanced riders, while Advance 20 is presented more as the easier / more accessible option. That may be true in practice, but it also makes it harder to isolate what is really happening mechanically. Is it the total fuse length? The mast-to-front-wing distance? The tail leverage? The rider level? Or just the marketing story?

I didn’t really want to rely only on brand narratives or assumptions, so I decided to test the parameter myself.
That’s where the One Ocean titanium fuselages were interesting. There is no heavy marketing story around this setting. Also, historically, the mast-further-back version came first, but the more forward mast version came only few month later. Thanks to the different tail lengths, I could compare two setups with almost the same total fuselage length while mainly changing one thing: mast position relative to the front wing.

The two setups were:

  • Ti Ultra Short 27.3 cm + 35 cm tail = 62.3 cm total length, with the mast in the more forward position (same as Advance+)
  • Ti Short 30.5 cm + 31 cm tail = 61.5 cm total length, with the mast about 30 mm further back relative to the front wing

That was the key point: isolating the effect of changing the mast-to-front-wing distance only, and moving the plate accordingly to maintain the front wing in the exact same position relatively to the board.

I tested both in dockstarting and winging (not enough wind for parawinging yet)

My takeaway: moving the mast slightly back gives noticeably more yaw stability. That is really valuable in conditions where you need some mental margin in dockstarting, winging or parawinging: confused water, ocean chop, boat traffic, seaweed, or any situation where you have to keep an eye on your surroundings instead of constantly micro-managing the foil.

I did not feel that it made roll harder to initiate. The foil still tips into turns easily. But because the yaw-roll coupling feels a bit more automatic, it takes slightly more energy to strongly open or close a turn. The upside is that it feels very relaxing: you don’t have to actively pilot all three axes all the time, and the yaw almost feels like it runs on autopilot through the turn.

Another important point: I found no noticeable effect on pitch stability. At least for me, mast forward vs mast slightly further back did not change pitch behaviour in any obvious way.

In terms of overall comfort, moving the mast slightly back at similar fuse length felt almost as beneficial as going to a longer fuse — but with a different trade-off. A longer fuse usually gives me that settled feeling at the cost of pumping cadence and low-speed pump efficiency. Here, I kept most of the easy pumping behaviour, but sacrificed a bit of radical turning ability instead. The foil feels calmer and more self-tracking, without becoming slow to pump.

In the end, I still fully see the point of a more forward mast position when the goal is maximum manoeuvrability, or when you want to bring more yaw liveliness to bigger front wings — especially at good downwind speeds, or in perfect pumping conditions where you want a very direct connection to the front wing.
But for dockstarting in more oceanic conditions, or even on flat water when I need to dodge weed, watch boats, or just keep more mental bandwidth available, I clearly prefer the mast slightly further back. Same for freeride winging.

Really interesting experiment. I initially thought these two titanium fuselages might overlap too much, but they actually change the foil’s character in a meaningful way. I’ll probably keep both.

So I’m curious: has anyone else actually tried to isolate mast-to-front-wing distance, instead of just switching fuse lengths? Did you feel the same kind of trade-off or am I over-reading my own setup?

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Takoon has just released a full Ti fuse and they chose to center it 2 cm forward (still 60 cm total length).

I’d like to get it but my biggest concern is the increased effort to pump that it creates having the front wing more ahead of the mast.

This is what Axis has to say about Adv vs. Adv20 (the Adv is 4 cm closer to the front wing):

Choose the Advance 20 if you:

  • Prioritize stability and predictability
  • Are early in your foiling journe y
  • Prefer a more planted and forgiving ri de
  • Not recommended for wings with a larger span than 1150 cm

Choose the Advance+ if yo u:

  • Want maximum manoeuvrability and responsi venes
  • Enjoy aggressive carving and tighter turns
  • Are looking to push the performance limits of your foi l setup
  • Recommended for all foil sizes (Fatty more suited to the largest spa n wings)

Riders looking for razor-sharp turning, maximum pumping efficiency, or those regularly using foils with spans significantly greater than 1150 mm will likely be better served by the Advance + range. However, if your priorities are fun, progression, and building confidence on foil, the Advance 20 is designed to help you get there faster.

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In my tests, I did not feel any loss in pump cadence, efficiency, or low-speed pump ease / getting high on the mast as long as the front-wing-to-stab lever arm stays similar. The foil felt more yaw-stable, not more pitch stable, and the trade-off was mainly a bit less radical turning, and a slightly less “3D” feel.

A longer fuse can slow the pump because it changes the stab leverage. Moving the mast position is a different parameter.
And a stiff titanium fuse keeps torsional flex under control without needing a bulky section, unlike aluminium, which makes bigger wings with a slightly rearward mast position much more viable, IMHO.

This guy beat you to it and experimented with both “radically short” but also extreme smashing the mast up to the front foil. Take a look at this video and also you can find some earlier prototypes and testing on the youtube channel.

I was personally extremely disappointed with Adrian when he talked about the testing campaign that arrived at 40mm for the advanced fuselages. I am almost certain that they ran out of track length on the testing campaign and as a consequence nobody liked the versions with the mast further forward than 40mm. He reported it was hard to get the board out of the water when they went forward of 40mm, and that sounds suspiciously like foil too far back in the box. There is no logical reason why a mast closer to the front foil could cause it to be harder to get the board out of the water.

Woah that’s extreme !

Very interesting experiment, there are two different innovations there. Extremely advanced mast position, but also insanely short fuselage that requires a huge rear wing to compensate…

Big rear wing = drag. It’s not an issue in winging, even flagged out the wing still push you a lot forward. But I do 90% parawinging (3 to 15k upwind downwind laps), and my biggest stab is a 105cm2. Once you experiment the benefits of small stab, there is no turning back.

Another parawing session on the rearward-mast fuselage… Damn, the carve feeling with the Fireball 1160 is so much more enjoyable than with the Advance+ equivalent.

And I can confirm again: I felt strictly no loss in pumping ability, as long as stiffness is on par. That’s exactly where titanium fuselages make sense, they allow that mast position without the setup becoming vague or twisty.

The Axis range were made drastically better when they reduced the mast-to-front-wing distance with the Advanced +
No other brands really messed too much with it as I guess the sweet spot is quite obvious.

Except Gofoil, who moved their mast backwards, which I still find quite interesting, and they seem popular with wake foilers. Interesting development

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I looked at this a bunch a year or two ago. Perhaps you can run with it more than I chose to.

I stopped looking at it because I only ride skinny, short chorded masts at this point. The difference in impact from shortening the front fuse length on a standard mast vs a short chord felt amplified. As such, I started looking at the distance to both front and rear of mast, and how various masts with different shapes became involved. It was all too complex for me to get any solid conclusions to share with other people. Bottom line was that for myself, a short chorded mast with a small tail 130² or less and foils under 950mm in span were not behaving favorably with the reduced front fuse.

If I were to make a hypothesis, I’d expect that some of the new, hyper advanced masts might not be compatible at all with some front fuse lengths while they might be amazing with others.

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@Matt Yeah, I get the Axis point, and I’m not saying the Advance+ logic is wrong. It clearly worked well for a lot of their older wings.
There’s also a clear structural reason to put the mast closer to the front wing: it reduces the load on the fuse, so you can get the stiffness you need with a slimmer, lower-drag section. I totally understand why brands go that way.

But the Fireballs and the Skinny stabs came later, and they’re a pretty different setup: more DW-oriented wings, smaller stabs, differents trajectories. So I’m not sure the same conclusions apply automatically. That’s exactly why I wanted to test it myself rather than just repeat the marketing. I’m not trying to say “rearward mast is better for everyone”. Just that with a stiff titanium fuse, similar total fuse length, and the Fireballs, I prefer the feeling.

For my riding style and skills (reasonably correct parawing level, consistent tacks, and able to ace >10 km downwind runs), the rearward-mast setup feels nicer: more settled in yaw, better carve feel, and I still don’t feel any loss in pumpability. Maybe it’s just personal taste, but that’s the point. I wanted to actually try it, not just assume the brand story was the full answer.

And if you look at AFS or Takoon, their newest Ti fuselages also seem to place the mast a bit further back again :wink:

@Wouzel You’re totally right! The mast chord may be involved in the locked feeling and yaw freedom perception. I ride a 108mm chord mast which may be considered as a skinny one, that may explains why I more at ease with a more yaw-stable setup

Sorry yes i wasn’t criticising it was more just my reflections. The gofoil one blows my mind. I’m very much only focussing on surf at the moment, so pumping and the finesse lest of a consideration

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The mast to wing distance mainly provides yaw stability and oscillation damping. I have played with this a bunch and would tune depending on board size and weight as well as rider skill/discipline.

A bigger board makes the foil feel small because the extra swing weight and rotational inertia reduces effectiveness of the foil’s natural damping characteristics.
To get the same feel you must change area and its distance away from the pivot point.

The foil also needs to move farther in the box than the change in distance from mast to wing because of changes in center of gravity of the foil.

This how brands like Alpine foil run the mast almost on top of the wing no problem- they are used for pump foil with the smallest lightest boards.

This is also why I slightly change the center of pressure location to the mast of my front wings across sizes/models to tune for assumed board use of each wing. My beginner foil sits 20-30mm farther forward from the rest because you usually use it with a giant heavy board.

You can get into a niche space as well where yaw damping is really low but roll and pitch are high enough to make it comfortable (or other variations of this)

If we made truly custom foils I would have a different fuse for every board haha.

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Never even got to scratch the surface of introducing board variables. Just keeps emphasizing that every detail matters.

Ok a few comments from what I know.

The axis testing that led to the advance was very far from scientific and was based almost entirely on trying to get some of those axis foil sections of the time to turn. Today you might hear axis riders with one ocean masts preferring their front fuse a little longer than the axis advance.

Comments from Alex of Gofoil fame when Adrian went smaller front fuse and Gofoil went larger front fuse was that Gofoil turn very nicely without having to stick the front foil under the mast like axis did.

Gofoil have been messing a lot again this year with this mast to front foil dimension and for different applications it may seem different lengths make sense.

My last 4 years on Fone and now f4 and I can’t believe how unstable and hard to control the axis foils are that I have tried. Art pro, fireballs, and surge. Most brands I jump on feel comfortable immediately whether I like them or not with the only exception being axis.

My wife’s latest Gofoil foils have the most lovely carvy feeling and yes are very yaw stable but at the same time very lively to turn. I keep looking at the front fuse in shock at how it feels compared to how it looks.

There are so many variables going on here that it is very very hard to test for. For example longer front may need less stabilizer in some way. In some ways your testing for feel which is very subjective of course.