Mast Placement on Fuselage

[joekitetime]

Howdy experienced foilers! So much good advice here, so thanks!

I'm struggling with understanding mast placement on fuselage. I am experimenting with mast length, stabilizers and foils and I am stumped on a certain issue.

I have a "regular" moses surf fuselage, and I also have a "jim stringfellow" fuselage for my large moses wings. As many know, he seemingly moved the mast back about 2" on the fuselage to solve the problem of not being able to move the large moses wings back far enough in the board's tracks.

While riding yesterday I was fighting the board feeling really tight. Maybe it had nothing to do with the mast and everything to do with the stab or wing, or my age!

But here is my question:

Does it make any difference in the riding performance if the mast was attached to the front of the fuselage, atop the wing, or the back, atop the stabilizer, or smack dab in the middle. Does it affect the center of rotation (the yaw) of the foil? Does moving the mast back 2" make the yaw more or less stable? (or, looser or more tracky?) Or does it do nothing?

Very curious to know if anyone has any experience with this.

Lastly, I really like the stringy fuselage because on the really big wings it allows my back foot to be right on the bump on the rear pad, but now I am curious as to whether that 2" further back may have other performance changes as well.

Thanks so much for your input.

[joekitetime]

Tucker at Mackite gave me my answer, spot on reply!

And, to boot, he told me about a new Moses adjustable fuselage that Moses came out with that addresses this very issue!

[Peter_Frank]

Snip...
I have a "regular" moses surf fuselage, and I also have a "jim stringfellow" fuselage for my large moses wings. As many know, he seemingly moved the mast back about 2" on the fuselage to solve the problem of not being able to move the large moses wings back far enough in the board's tracks.
Snip...

Hi

Something is wrong with what you write above.

If you move the mast rear on the fuselage, then you have to move the mast further rear in the tracks - and you write the Stringfellow was made like this so you did not hit the rear of the tracks - something is wrong here

But to your main question, the mast position on the fuselage means a lot in terms of hydrofoil handling, in particular when turning it makes a huge difference.

Having mast dead center over the wing sounds like an easy and "strong" way, it just does not work well.
The foil becomes odd and slippery even when riding straight, and really odd in turns.
Also tried on monowings, possible and maybe mostly different, but still seems like not as good as having the wing in front of the mast.

If mast is extremely rear, it will of course give mechanical challenges, huge load on the connection points both fuselage and board, and can destroy these
Apart from ending up behind the rear end of the foilboard - so to no use...
Not sure if the only reason, the thing is just, I dont know how it feels if too far rear.

You can ride on the hydrofoil no matter where the mast is on the fuselage, yes, but so many has tried moving it back and fourth on the fuselage (some of my friends too), and found the typical current position to work best overall, no doubt.

Peter

[alowishus]

Tucker at Mackite gave me my answer, spot on reply!

And, to boot, he told me about a new Moses adjustable fuselage that Moses came out with that addresses this very issue!

joekitetime,
Are you able to share Tucker’s response?

I only have the “Stringy” fuse, which I quite like and it seems to ride fine, it moves the mast forward 40mm I think, but I have the Foilmount adapter for Slingshot masts, which moves the mast back again a bit... So the nett effect may be insignificant.

As Peter perhaps intimated, roughly where the manufacturers put them is about right because they ride better at that position.

You said you have the Moses surf fuse and the Stringy fuse, the same fuse essentially except with the mast in different positions. What’s your comparison? Unless you meant you have the Moses kite fuse.

[joekitetime]

Tucker at Mackite gave me my answer, spot on reply!

And, to boot, he told me about a new Moses adjustable fuselage that Moses came out with that addresses this very issue!

joekitetime,
Are you able to share Tucker’s response?

I only have the “Stringy” fuse, which I quite like and it seems to ride fine, it moves the mast forward 40mm I think, but I have the Foilmount adapter for Slingshot masts, which moves the mast back again a bit... So the nett effect may be insignificant.

As Peter perhaps intimated, roughly where the manufacturers put them is about right because they ride better at that position.

You said you have the Moses surf fuse and the Stringy fuse, the same fuse essentially except with the mast in different positions. What’s your comparison? Unless you meant you have the Moses kite fuse.

Hey Joe,

Yes, the further back you push the wings (pushing your stance forward) the less responsive the foil will become in the yaw and pitch. Roll should remain similar. You are moving forward of the pivot point so you lose leverage. If you want to increase maneuverability but reduce lift you can go with a smaller stabilizer or shorter fuse.

The mast position in relation to the wings is also a consideration but not so much as the wings to the stance. The stringy fuse does make it a little more manoverabile since the mast drive is moving forward along with the stance. Especially with the flatter wings with less winglet drive. Personally, I think the Surf wings feel better on the stringy fuse. Except maybe the really fast ones like the 720.

This new custom fuse will let you play with mast placement, fuse length, and stabilizer angle a bit. I call it the "super-fuse". Just released after a few months of my testing....
https://www.mackiteboarding.com/custom- ... -fuselage/

-Tucker

[alowishus]

Good info. Thanks.
Behold the Super Fuse - Looks awesome

[Windigo1]

I made a fuselage for the 633 so I could mount the wing to my existing aluminium masts I moved the mast as far forward as I could the foil is extremely stable and the front foot pressure is reduced but I'm not impressed by the speed. However I do have a pretty large stab on it. A smaller stab might improve the speed but It will make it more twitchy.

[Peter_Frank]

Sorry, I know it might be me, but this thread is extremely confusing...

I can not find head nor tails in the postings and descriptions.

Moving the whole foil forward or rear, or the mast on the fuselage, will of course affect the trim (where you have to stand for balance), but it goes without saying, and is not the topic in this thread.

The question, as I read it, was how a different mast position on the fuselage will affect overall feel and dynamics.
Everything else being equal and the mast position on the board of course displaced the exact same amount so trim is not an issue

Maybe simply a different way to understand the expressions, and something else changed "taken as given" is not written in text?
For example, if you have a fixed feet position (say straps only one set of inserts), and you move the mast forward or rear on the fuselage, you also have to change stabilizer and AOA on stab (of course).
Or how should it be understood?

This is a very interesting subject, the very mast position on the fuselage and how it affects, but really confusing reading this thread, for me

I cant be the only one not understanding, or?
If only me, someone please explain what is meant, thank you

Peter

[joekitetime]

Sorry, I know it might be me, but this thread is extremely confusing...

I can not find head nor tails in the postings and descriptions.

Moving the whole foil forward or rear, or the mast on the fuselage, will of course affect the trim (where you have to stand for balance), but it goes without saying, and is not the topic in this thread.

The question, as I read it, was how a different mast position on the fuselage will affect overall feel and dynamics.
Everything else being equal and the mast position on the board of course displaced the exact same amount so trim is not an issue

Maybe simply a different way to understand the expressions, and something else changed "taken as given" is not written in text?
For example, if you have a fixed feet position (say straps only one set of inserts), and you move the mast forward or rear on the fuselage, you also have to change stabilizer and AOA on stab (of course).
Or how should it be understood?

This is a very interesting subject, the very mast position on the fuselage and how it affects, but really confusing reading this thread, for me

I cant be the only one not understanding, or?
If only me, someone please explain what is meant, thank you

Peter

Hi Peter, Joekitetime here. My original question was answered by Tucker at Mackite. Perhaps my wording of the question was confusing, but Tucker got it immediately and fired off the answer promptly.

The issue I was having had to do with the different "feel" I got when using a Moses fuselage compared to a Stringy fuselage. As you are aware, Stringy moved the connection between the mast/fuselage back approx. 2" in order to move the center of balance 2" on the board due to folks running out of room off the back of their boards for the Moses 633 and subsequent large surf wings. That got me thinking about how the connection point between the mast and and fuselage, fore or aft, affects the performance of the foil.

Tuckers answer nailed it. But to summarize:
The roll is not affected, whether the connection is closer to the stabilizer or the front wing...
The pitch is dulled the further forward the mast is connected to the fuselage, same with yaw.

So, if you want to "liven" up the foil, rather than move the mast back (beyond the 2" which stringy did), you must shorten the fuselage and reduce the size of the stabilizer (if that is what you are after).
If you want to add stability, move the mast connection forward (the "standard" placement Moses uses), increase stabilizer size and/or lengthen the fuse.

Clear as mud!

I experienced with the larger wings fighting the foil for hard turns, as well as the foil sliding out. I assumed it had to do with the re-positioning of the mast/fuse connection with the stringy fuse. But it did not. If anything that helped. The real culprit was the 483 stabilizer. It added too much stability (roll), but because it is flat, althought the yaw was playful and twitchy, at high speeds the stabilizer would slide. So I didn't have good traction all the while fighting a stiff ride. The 450 stabilizer solved the problem.

I hope that helps!

[ScoopZ]

You keep saying the connection for the 743 stringy is moved back in the fuse by 2", I think this is where the confusion is coming from.

Grigorib's pictures shows the stringy fuse(top one) with the mast holes moved toward the front wing (in comparison to the Moses made fuses) to allow the required stance/pivot point with short tracks.

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