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Mast Position?

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junebug
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Mast Position?

Postby junebug » Thu Jul 26, 2018 3:41 pm

I’m using a SS Dwarfcraft 3’6” right now with 2 front straps and no back strap. I have the back of the mast plate set on the 5cm setting. (My foil is a Lift 150.) I’ve never measured the actual distance from the back of the board, but I would estimate it is at least another 5cm. I have experimented a little with mast placement, but I haven’t given it a real try with it further back because my back leg gets too tired on long tacks.

My question is this: other than lift differential—i.e., all else being equal, the further back you put the mast the less lift the board will have, and the implications of that fact on foot pressure—are there any other differences that mast location makes? Greg Drexler rides with the mast at the back of the board, and the Kanaha Shapes board doesn’t have tracks, but, instead, just has inserts at the back of the board. What are the benefits of this? Does the foil respond differently in turns with the back foot right over the mast as opposed to behind the mast?

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Re: Mast Position?

Postby kitexpert » Thu Jul 26, 2018 7:06 pm

Don't over complicate it. Whether your back foot is on top of the mast or slightly behind it depends mainly on the location of the front wing and your stance width. General rule which I've noticed true is that front wing is between your feet.

But because mast - front wing distance varies in different foils you can't give exact advice for the feet location in relation to mast. And of course stance widths vary as well.

If mast is too far back board becomes too short at the back. Then it will be for sure tiring to try to create back foot pressure when there is no room for leverage to do so.

You can measure the distance between questimated CoL of the front wing (perhaps 30% of the chord) and mast LE and mark this point on top of the board. Then feet should be symmetrically to this point. I did this when I was practicing and it helped me to find correct place for the feet right from the start.

Stabilizer (size, AoA) affects feet location also, but if it (and else) is correct you can stand straight and relaxed on the board, having quite equal front/ back foot pressure.

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Re: Mast Position?

Postby junebug » Thu Jul 26, 2018 9:29 pm

So are you saying mast placement does or doesn’t affect things other than the relative foot pressure needed?

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Re: Mast Position?

Postby sixdivision » Fri Jul 27, 2018 8:33 am

I just started foiling and I heard a teacher say that mast placement influences speed. Not sure if that is true...he mentioned mast placed more to tha back makes it faster but less stable, mast more to the middle makes it slower but more stable. Again, I've not been able to verify, just getting the hang of it...I'd be interested to read more opinions on the subject :-)

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Re: Mast Position?

Postby kitexpert » Fri Jul 27, 2018 9:54 am

Main thing is how you feet are in relation to the front wing. It creates the lift, the force you must control and balance on with your body (weight).

Feet placement in relation to mast is a result of that. If you check Drexler videos you can see front wing is in between his feet. Because he uses such a small board there is not much choice where his feet are.

If you move foil attachment in your board you move your stance location as well.

These are basic reasoning/observations from not so experienced hf'er :)

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Re: Mast Position?

Postby junebug » Fri Jul 27, 2018 12:00 pm

So are you saying mast placement does or doesn’t affect things other than the relative foot pressure needed?

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Re: Mast Position?

Postby Kamikuza » Fri Jul 27, 2018 12:07 pm

FWIW this is my opinion, it's probably all wrong :D

It's all about balance and it's all relative. Just think about levers, like standing on top of a see-saw...

Doesn't matter where your feet are relative to the foil wing or mast, there's no "correct" position.

If you have a board and foil "set" then it's probably designed to have your feet in the center of the straps, with wiggle room fore and aft for preference. Then you set the foil in the track according to preference too.

The closer your back foot is to being over the mast, the more yaw control you have, the more the pitch control is about the front foot. And IMO the more your turns are about a change of heading and not carving.

The further your front foot is from the front wing, the less input your front foot needs (think longer lever arm), so you end up with more pressure on your rear foot.

You can shim the stab or just move the foil in the mount, it achieves the same thing -- with some caveats.

Here's how I set up a new foil -- get a comfy stance width. I aim to have my feet in the center of strap holes in case I want to fully strap, but usually I only use the front ones for water starting.
I like balanced pressure on my feet and positive control from the rear, so I tend to have my back foot back from the mast, with the mast forward in the tracks.

As I've progressed to bigger wings, I've found the mast moving ever forward so finding the perfect set up for a given wing can take some fiddling...and because I can't be bothered coming in off the water to fiddle, I tend to test just one set up per session :D

This will probably all change as I get better :lol:

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Re: Mast Position?

Postby DAnderson » Fri Jul 27, 2018 3:22 pm

I also ride the same setup, 3'6 & 150 wing w/ a single strap in the forward position. I have the mast set @ the 3cm from rearmost position. My opinion after adjusting it several times, is further rearward increases rear foot pressure. Which certainly can get uncomfortable after an hour or so. This is accentuated w/ a longer mast.

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Re: Mast Position?

Postby Laughingman » Fri Jul 27, 2018 4:14 pm

DAnderson wrote:
Fri Jul 27, 2018 3:22 pm
I also ride the same setup, 3'6 & 150 wing w/ a single strap in the forward position. I have the mast set @ the 3cm from rearmost position. My opinion after adjusting it several times, is further rearward increases rear foot pressure. Which certainly can get uncomfortable after an hour or so. This is accentuated w/ a longer mast.
This is counter intuitive.
If you move the mast back then your general overall weight is more forward then it was if you stand in the same spot. I think what you are experiencing is fatigue due to not putting your weight on the rear foot but yet having to maintain control with that foot. I have to keep my rear foot in front of the strap and have my mast as far back as possible if I move my foot back, I also get fatigued but not because I am putting weight on my back foot, its because I cannot. Moving the mast forward would require me to move more forward or put more weight on my front foot.

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Re: Mast Position?

Postby juanpasala » Fri Jul 27, 2018 4:55 pm

To the best of my knowledge:
If you intend to ride fast, then the front wing of the foil will want to go up, so the mast positioning should be towards the back in order to have a more comfortable weight distribution and not having to overcompensate with either leg.
Same thing goes if you want to go slower, then mast should be more towards the center, as the speed of the foil wont generate to much lift anf front pressure wont be as high.
Then again, this will change depending of the preferences of each rider and the foil you are using.


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