Do you set the mast perpendicular to the board ( ie at 90 degrees). Do you check with a square or eye ball it or don't consider it matters.
If it does make a difference what are your experiences.
I've been told on 1 occasion that I was flying slightly nose down and I've seen one out seemingly very nose up. I've also seen a foil with the mast raked forward at the fuse.

Never measure mast angle. I just try to make sure it is secure in the box or tight in tracks. I did break a bolt once and the mast inclined forward about 5 deg. I could still get flying and keep flying but it took lots of extra back foot pressure, which doesn't really make sense to me as the foil was angled 5 deg up!

If its off a degree or two I cannot see it making much difference, perhaps the nose is slightly higher or slightly lower than horizontal but that isn't a big deal.

It's the "wing" angle - angle of attack (AoA) that matters. Fortunately most manufacturers design their fuses to be inline with their fuses so we usually just measure flat part of the fuse compared to the board bottom instead. You can use a cheap digitial level or a cell phone app. Almost all manufacturers bake in an angle from 1.5-2.5 degrees. That is the board points that much higher than the fuse

There have been extensive threads on here. Search for "mast rake". It does make a bit of a difference in things like take-off, touch downs and rotating the rider more or less forward over the wing and you definitely don't want 0 degrees but, again, this is ultimately determining wing angle not just the mast itself.

As thedoor suggests, getting the mast properly seated in and even will get you most of the way there. More experienced riders and especially racers are more sensitive to mast rake which is why shims that sit on top of the mast head are available to fine tune the angle.

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Paducah said..
....fuses to be inline with their fuse...

Should be
...wings to be inline with their fuse...

Heavens, I'm brain dead sometimes.

I made a shim for mine (posted pics on old thread), set angle to 0.0 for an AFS W95 foil on a Goya Bolt, perfect for me.

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thedoor said..
Never measure mast angle. I just try to make sure it is secure in the box or tight in tracks. I did break a bolt once and the mast inclined forward about 5 deg. I could still get flying and keep flying but it took lots of extra back foot pressure, which doesn't really make sense to me as the foil was angled 5 deg up!

If its off a degree or two I cannot see it making much difference, perhaps the nose is slightly higher or slightly lower than horizontal but that isn't a big deal.

The back footedness is because due to with the foil being angled upwards, once the fuselage is flying level, the board is flying nose down. This means the length of the sides of the triangle between your feet and your weight changes. The front foot sits lower and the back foot sits higher, hence you'll feel like you have to bend the backleg more to balance everything out. I prefer the front foot to be higher up than the back foot pretty much always (so positive rake of the board vs the foil flying level), meaning you have to bend the front leg a little for "evenly distributed weight" between both feet. This is independent from whether your weight should actually be further back or forward to maintain balance.

Changing the rake angle is a usual fine tuning. Most of the time, you tilt the mast back (ie make the foil point down when you're not flying). Two goals :
1-if you're incrinsing your speed, you reduce the wing angle of attack, so you need to point down the nose of your board. So having the foil already down put the board back in line, better in aligned with the air flow. This is more significative on longer board.
2-it helps making the occasional touch down smoother, and more likely to be touch and go. As you ride slightly more nose up, you touch down with the aft part of the hull rather than the nose.
I use a 1? shim below my DTT head thicker at the front. My foil is designed to have the fuse inline with the hull.

I feel it makes a big dofference on race kit. I use a 1.5 shim on my mast head which does a couple of things:

1. It reduces the amount of downward force on my board from gusts when i'm sailing along which allows a more stable flight.

2. It helps a lot with touchdowns when hammering downwind because the nose is slightly higher, so if i do touch the water, im not getting catapaulted over the front as much. Most guys on race gear run between 1.5 to 2 degrees for upwind downwind foiling, and 2-3 degrees for slalom foil racing. The measurement is done on the fuse at back of the wing.

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Paducah said..
It's the "wing" angle - angle of attack (AoA) that matters. Fortunately most manufacturers design their fuses to be inline with their fuses so we usually just measure flat part of the fuse compared to the board bottom instead. You can use a cheap digitial level or a cell phone app. Almost all manufacturers bake in an angle from 1.5-2.5 degrees. That is the board points that much higher than the fuse

There have been extensive threads on here. Search for "mast rake".

I made a search with "mast rake" but there are many discussions coming up. It is still not clear to me the angle of the fuselage in relation to board for the Starboard race foil set up. I noted the following angle from the Phantom site and the picture is showing 3degrees. Another beginner in our group sanded too much his brand new mast tuttlehead to fit in the box but his angle is now probably 6-7 degrees. Another foiler also made a youtube video showing some of his set up using a phone leveler for the Starboard set-up that is showing 2.4 degrees. When I am inserting my mast to the tuttlebox, I am not sure how tight I need to put pressure to front and back screws to get the correct angle of the mast. I realize the race set up is different than the freeride foils and I am not able to find good guidance on this issue. In any case, if someone could clarify this terminology and the starboard race foil set-up without going into engineering terminology, it will likely benefit others and this group has been very useful for me to get some wisdom.

That is how I checked my mast rake, bubble level app on phone, and the board and fuselage. the Phantom -3 degree rake seems like a lot, but they should know for their foil! AFS has a negative rake built into the mast head flange, and they should know too. Maybe, the rake angle is different on a foil specific board, versus a slalom board? I find having 0 degree rake to work perfect for me on a slalmon board.

The phone apps may be precise, but are they that accurate?
Another way to measure rake could be measure distance from fuse to board in a couple of locations plus distance along the fuse between the measurements. Then just use simple trigonometry (Im assuming no rocker in section of board being measured)

I had the same issue mast not 90 deg in board..{gtr foil}
the phone apps we used all said mast was close to 90..eye sight and good old fashion metal square said other wise
I have posted the pics on here before.
so while away for a week I played with shims till mast was 90 deg with square
yep flew so much eaiser with a true 90 deg mast even better with mast kicked forward a bit

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SA_AL said..

Paducah said..
It's the "wing" angle - angle of attack (AoA) that matters. Fortunately most manufacturers design their fuses to be inline with their fuses so we usually just measure flat part of the fuse compared to the board bottom instead. You can use a cheap digitial level or a cell phone app. Almost all manufacturers bake in an angle from 1.5-2.5 degrees. That is the board points that much higher than the fuse

There have been extensive threads on here. Search for "mast rake".

I made a search with "mast rake" but there are many discussions coming up. It is still not clear to me the angle of the fuselage in relation to board for the Starboard race foil set up. I noted the following angle from the Phantom site and the picture is showing 3degrees. Another beginner in our group sanded too much his brand new mast tuttlehead to fit in the box but his angle is now probably 6-7 degrees. Another foiler also made a youtube video showing some of his set up using a phone leveler for the Starboard set-up that is showing 2.4 degrees. When I am inserting my mast to the tuttlebox, I am not sure how tight I need to put pressure to front and back screws to get the correct angle of the mast. I realize the race set up is different than the freeride foils and I am not able to find good guidance on this issue. In any case, if someone could clarify this terminology and the starboard race foil set-up without going into engineering terminology, it will likely benefit others and this group has been very useful for me to get some wisdom.

I hd the same question when I got my iQFoil foil (same as the race setup: plus fuselages but stiffer mast). Gonzalo Costa -Hoevel, involved in the iQFoil, told me to measure the angle right behind the front foil (the board upside down) and it should be between 1 and 2.5 degrees, ideal between 1.5 and 2. Edit: the degrees above are the difference between the bottom of the board and the fuselage

Luuc van Opzelande wrote me reg. the Moses/Sabfoil 107 race:

5-9 knots -3,0/-3.5
10-15 knots -2.0/2.5
15- 20 knots -1,8/2.0

Luuc wrote: for the degrees, i am gonna give you a guide line, please consider that its based of my weight 98 kg, so take of some angle if you are lighter or increase when heavier.

For racefoils between 1.5 and 3 degrees backward rake (nose up) is a good startingpoint. I rode my Loke Race with 1.7-2.4 degrees depending on water state and wind, could probably have used some more rake in some conditions, but never got to making extra shims. I'm not sure how Luuc measures (what does -3 mean?) Perhaps his foil has some built in rake and he reduces it? I'm very sure he isnt riding with his nose down, and as far as I know he sticks to the same principals as me, we rode quite a lot together in the past few years: Set the board up to be more nose high as wind / speed increases, less nose high for up-down racing than for slalom.

Any recommendations for purpose built Digital Levels?

I'm considering purchase of a level from a model train catalog that's used for measuring track grades and super elevations (Micro Mark, miniature digital level, item #84519). It has buttons for setting "relative zero" and can display both "degrees" and "percent difference from sea level." The reading surface is 2" and price is $50 US. The relative zero seems likes a good feature.

the level box:

www.amazon.com/dp/B09967M1QQ/ref=sr_1_3_sspa?__mk_de_DE=?M????&crid=10X2E0E5VPVGR&keywords=level+box+digital+angle+gauge&qid=1639844159&sprefix=level+box%2Caps%2C232&sr=8-3-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExT1gxMFlMMFZTUkU2JmVuY3J5cHRlZElkPUEwMzk3MjE5TTNXRVJUWFA1UEhOJmVuY3J5cHRlZEFkSWQ9QTA5ODY3NzMzUklGNzVVNU1HWVJGJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==

Thanks for the quick reply and recommendation.

Would you explain your measuring process, I'm guessing you're using the "relative zero mode" to establish the board bottom as zero. Do you set the zero point from the front of the Tuttle box or perhaps over a longer distance by using long board to capture a blend of the rocker?

I use an app called "bubble level" with my iPhone. It is as accurate as my 4ft level and my laser level.

-first I set the level box on the bottom directly in front of the mast (which is properly fixed - ready to fly)
-I put the zero funtion
-than I take the level box and place it on the fuselage - alway on the same place (I do it in the middle between the 2 or 4 screws, which connect the fuse to the mast)
-if angle is between e.g. 2 and 2.5 (for 91 cm board with 1000 or 800 foil) than i start foiling.
-if I come back after 1h-1,5h of foiling I'm remeasuring, to see, whether the mast was really fixed in the box
-If I want better lift or better rebound from touching on the water, that I increase the angle, if the nose of the board seems to high in low wind conditions, I decrease the angle.
-therefore I use the shims of the goybox (1-10 mm) or cutom made shims (1-12 mm)
-normally I used 6,7 or 8 mm Shims (PD AI Hybrid 91 and Moses/Sabfoil 107)

Goybox:
www.phantom-windsurfing.com/spare-parts/p/goybox

Interesting thread. So to be safe on a box install, rake mast back a degree or two?

There many angle information from the developer and teamrider available.
www.phantom-windsurfing.com/settings

For the Phantom and Moses/Sabfoil Foils the rake angles seem to bit a higher - I start training and testing with 2,5.
Fot the Starboards Race and IQ, the mentioned angled are smaller (but I don't have these foils - so somebody else must answer that).

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Mark _australia said..
Interesting thread. So to be safe on a box install, rake mast back a degree or two?

I may be wrong (happy to be corrected) but I'd think that a good part of the angle is baked into the foil mast and assumes the box is even (zero) with the bottom of the board. Hopefully the couple of guys who actually have built a few boards on here will chime in.

^^That's why I ask. As on factory WS boards there is often a smidge of toe in on fins - just so if something goes wrong at least they're not toed out.
So wondering if consensus would be to rake mast back just a tiny bit when installing a box?

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Mark _australia said..
^^That's why I ask. As on factory WS boards there is often a smidge of toe in on fins - just so if something goes wrong at least they're not toed out.
So wondering if consensus would be to rake mast back just a tiny bit when installing a box?

Problem is the rocker is not flat either. If you have tailkick the box is already raked backward relative to the deck. I wouldnt overthink it, put it in flush and fix the angle with shims if you feel you need to. The effect of rake is dependent on so much factors, the angle of the deck relative to the box is an important one, as that determines in part how the power is distributed over the legs, the noserocker, length of the rocker flat and widest point of the outline are other factors as they all affect touchdown behavior in a way.

Most foils are setup with very similar angles. The issue is how they are measured. As per WOW and Maddlad they should be between 1.5 and 3 degrees. ( This is the difference between the bottom of the board and the actual front wing angle)
For a starboard setup this is easy to measure as the front third of the fuselage is actually angled up 1 degree and this matches the actual wing angle. Other foils ( like Phantom) the fuselage is straight without the kink, then they set the front wing at about 1 degree.
So. If you measure a Phantom setup on the fuselage, a reading of 4 degrees is equivalent to 3 degrees wing angle on a starboard foil.

Mark - You just try to set the box in level. Then for example an IQ foil correctly / fully seated into the box will have the correct foil angles already built in ( about 1.75 degrees from memory ) They can then shim the rest to suit requirements.

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mmm13b said..
I had the same issue mast not 90 deg in board..{gtr foil}
the phone apps we used all said mast was close to 90..eye sight and good old fashion metal square said other wise
I have posted the pics on here before.
so while away for a week I played with shims till mast was 90 deg with square
yep flew so much eaiser with a true 90 deg mast even better with mast kicked forward a bit

I know for the bubble level app you have to first zero it on the board bottom using a flat edge of the phone, and then without moving the the board measure the angle on a flat section of the fuselage (mast screwed in tight to board). After measuring the angle on the fuselage I always go back to the board bottom to make sure the bubble level app is still reading zero. Does not take much for the upside down board to move a little when resting the phone on the fuselage.

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Sandman1221 said..

mmm13b said..
I had the same issue mast not 90 deg in board..{gtr foil}
the phone apps we used all said mast was close to 90..eye sight and good old fashion metal square said other wise
I have posted the pics on here before.
so while away for a week I played with shims till mast was 90 deg with square
yep flew so much eaiser with a true 90 deg mast even better with mast kicked forward a bit

I know for the bubble level app you have to first zero it on the board bottom using a flat edge of the phone, and then without moving the the board measure the angle on a flat section of the fuselage (mast screwed in tight to board). After measuring the angle on the fuselage I always go back to the board bottom to make sure the bubble level app is still reading zero. Does not take much for the upside down board to move a little when resting the phone on the fuselage.

I feel that if I set up the back angle (not front) of the mast as 90 degrees (picture below), that will set up at the required rake for the foil. When I am pushing the mast to fit tightly to the box, the angle may not be precise since most are pushing back and forth as in the picture but not getting correct angle. Few times I made the screws as tight as possible but after coming back from my session I found the angle was off and the screw was loose, likely I did not set up the mast correctly.

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SA_AL said..

Sandman1221 said..

mmm13b said..
I had the same issue mast not 90 deg in board..{gtr foil}
the phone apps we used all said mast was close to 90..eye sight and good old fashion metal square said other wise
I have posted the pics on here before.
so while away for a week I played with shims till mast was 90 deg with square
yep flew so much eaiser with a true 90 deg mast even better with mast kicked forward a bit

I know for the bubble level app you have to first zero it on the board bottom using a flat edge of the phone, and then without moving the the board measure the angle on a flat section of the fuselage (mast screwed in tight to board). After measuring the angle on the fuselage I always go back to the board bottom to make sure the bubble level app is still reading zero. Does not take much for the upside down board to move a little when resting the phone on the fuselage.

I feel that if I set up the back angle (not front) of the mast as 90 degrees (picture below), that will set up at the required rake for the foil. When I am pushing the mast to fit tightly to the box, the angle may not be precise since most are pushing back and forth as in the picture but not getting correct angle. Few times I made the screws as tight as possible but after coming back from my session I found the angle was off and the screw was loose, likely I did not set up the mast correctly.

For my AFS W95 foil I used silicone grease to help get it in (was really tight), after a while it no longer needed the grease, and now slides in smoothly. And the top of the mast head has an angle/slope to it like any fin does, so there was space between the mast head and top of the DT box, and the screws were always loose after a session. When I made a shim for the mast head to set the angle to 0.0 degrees the shim also filled in the gap between the top of the mast head and DT box, then the screws stopped coming loose.

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Sandman1221 said..

For my AFS W95 foil I used silicone grease to help get it in (was really tight), after a while it no longer needed the grease, and now slides in smoothly. And the top of the mast head has an angle/slope to it like any fin does, so there was space between the mast head and top of the DT box, and the screws were always loose after a session. When I made a shim for the mast head to set the angle to 0.0 degrees the shim also filled in the gap between the top of the mast head and DT box, then the screws stopped coming loose.

Great I may try the grease. How did you make the shim for the mast head? Those are not commercially available. Could you provide description of making the shim and a picture? Thanks

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SA_AL said..

Sandman1221 said..

For my AFS W95 foil I used silicone grease to help get it in (was really tight), after a while it no longer needed the grease, and now slides in smoothly. And the top of the mast head has an angle/slope to it like any fin does, so there was space between the mast head and top of the DT box, and the screws were always loose after a session. When I made a shim for the mast head to set the angle to 0.0 degrees the shim also filled in the gap between the top of the mast head and DT box, then the screws stopped coming loose.

Great I may try the grease. How did you make the shim for the mast head? Those are not commercially available. Could you provide description of making the shim and a picture? Thanks

Look at goy'box on the Phantom website
www.phantom-windsurfing.com/spare-parts/p/goybox

and this:
www.free-ride-addicted.fr/e-boutique/cales-de-rake-3/
www.free-ride-addicted.fr/e-boutique/cale-de-rake-boitier-cobra/