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Hello,
I have a big problem with my F4 race foil mast 97cm. when i ride the mast constantly moves in the boks , with a terrible crack. what to do? . Why the boxes on the boards are so deep and on the masts so shallow.
I am afraid something will not break
please give me some advice
thanks

Thighten your screws more. Like, really really really thight. I also skip any rubber washers between the metal one and the board for foiling, they only allow room for movement.

By thightening, I mean, get a T shaped tool you can sideways so you can really lever them, I use inbus screws because they're easier to thighten hard, philips head screws strip easily.

You could also fill up the box with rake spacers. Will get you a more consistent performance too probably, every time the mast moves your board rides different.

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bul131 said..

Hello,
I have a big problem with my F4 race foil mast 97cm. when i ride the mast constantly moves in the boks , with a terrible crack. what to do? . Why the boxes on the boards are so deep and on the masts so shallow.
I am afraid something will not break
please give me some advice
thanks

Spend some time on the beach getting the foil fully "bedded" into the box. The cracking you hear on the water is the foil head moving into that bit of left over space at the top of the box at the front screw

as you tension the bolts up shock load the foil mast (by bouncing the board backward and forward) so it descends into the box bit by bit, then add a bit more tension and redo, till it no longer wants to move further in. Don't rely on bolt tensioning alone, you'll always end up leaving a gap, and repeatedly using the m6 bolts to do all the work torquing the foil in will cause metal fatigue and they'll snap.

if you get into the habit of bedding the foil in properly the "cracking" will happen much less frequently. I've also fallen into the habit of giving the foil mast a push sideways either way at the end of the process to make sure there's no shifting left to happen.

When you're doing the above on the beach pay close attention that your bolts aren't too long. If they are you might not be able to properly tighten without damaging the board.

Use tefgel on those bolts

It'll be easier to tighten and will hold the tension better.

Don't overlook the possibility that the box is too shallow for the DT fitting on the mast. Measure it all. Many boards nowadays come with relatively shallow DT boxes. If the foil tops out inside the box, it means that the front and back rounded tapers are not seated, and it can move. You can often spot those because they have those recessed "chimneys" for the screws. Not good. It is a bad design, even for purpose-built foil boards.

This will mean MAJOR trouble. It will be too easy to break the box if the foil can move.

The goal is a tight, intimate, and completely seated touch of the front and back rounded tapers. They are what carry the load in a properly installed DT foil. The alternative is to use a foil with flanges around the top. The flanges seat against the bottom of the board to ensure a tight fit. Slingshot, SABfoil aluminum, and LP, among others, use flanges.

I have been able to shave off a few mm from the tops of my DT foils in order to ensure a fully seated fit. YMMV, but you have to be careful not to remove too much edge margin for the threaded barrel nut inserts.

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segler said..
Don't overlook the possibility that the box is too shallow for the DT fitting on the mast. Measure it all. Many boards nowadays come with relatively shallow DT boxes. If the foil tops out inside the box, it means that the front and back rounded tapers are not seated, and it can move. You can often spot those because they have those recessed "chimneys" for the screws. Not good. It is a bad design, even for purpose-built foil boards.

This will mean MAJOR trouble. It will be too easy to break the box if the foil can move.

The goal is a tight, intimate, and completely seated touch of the front and back rounded tapers. They are what carry the load in a properly installed DT foil. The alternative is to use a foil with flanges around the top. The flanges seat against the bottom of the board to ensure a tight fit. Slingshot, SABfoil aluminum, and LP, among others, use flanges.

I have been able to shave off a few mm from the tops of my DT foils in order to ensure a fully seated fit. YMMV, but you have to be careful not to remove too much edge margin for the threaded barrel nut inserts.

this is exactly the problem with me. the box on the board is deeper than the mast. thanks a lot for the advice

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bul131 said..

segler said..
Don't overlook the possibility that the box is too shallow for the DT fitting on the mast. Measure it all. Many boards nowadays come with relatively shallow DT boxes. If the foil tops out inside the box, it means that the front and back rounded tapers are not seated, and it can move. You can often spot those because they have those recessed "chimneys" for the screws. Not good. It is a bad design, even for purpose-built foil boards.

This will mean MAJOR trouble. It will be too easy to break the box if the foil can move.

The goal is a tight, intimate, and completely seated touch of the front and back rounded tapers. They are what carry the load in a properly installed DT foil. The alternative is to use a foil with flanges around the top. The flanges seat against the bottom of the board to ensure a tight fit. Slingshot, SABfoil aluminum, and LP, among others, use flanges.

I have been able to shave off a few mm from the tops of my DT foils in order to ensure a fully seated fit. YMMV, but you have to be careful not to remove too much edge margin for the threaded barrel nut inserts.

this is exactly the problem with me. the box on the board is deeper than the mast. thanks a lot for the advice

What board brand and model do you have? Many deep Tuttle boxes are much deeper than the mast head. For instance, my old formula board is 6 cm deeper than the mast head. Are you rocking the mast back and forth and tightening the bolts?
you can use dry lubricant on the mast head to make it easier to install.
Some new foilboards, like starboard, have boxes that are shallow enough so the mast head sits on top of the box. I think that makes it easier to set the mast and also allows you to set it at the right angle every time.

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segler said..
Don't overlook the possibility that the box is too shallow for the DT fitting on the mast. Measure it all. Many boards nowadays come with relatively shallow DT boxes. If the foil tops out inside the box, it means that the front and back rounded tapers are not seated, and it can move. You can often spot those because they have those recessed "chimneys" for the screws. Not good. It is a bad design, even for purpose-built foil boards.

This will mean MAJOR trouble. It will be too easy to break the box if the foil can move.

The goal is a tight, intimate, and completely seated touch of the front and back rounded tapers. They are what carry the load in a properly installed DT foil. The alternative is to use a foil with flanges around the top. The flanges seat against the bottom of the board to ensure a tight fit. Slingshot, SABfoil aluminum, and LP, among others, use flanges.

I have been able to shave off a few mm from the tops of my DT foils in order to ensure a fully seated fit. YMMV, but you have to be careful not to remove too much edge margin for the threaded barrel nut inserts.

While this might be -theoretically- the best solution , in practice it does not happen ;

- this would imply the load to be divided even between the front an back taper, but it isn't. Because the front wing is placed (far) forward, it's the front taper and back screw that takes most of the load. (when necessary, it's always the front screw that needs retightening during a pause)

- the "tight, intimate and completely seated touch" would mean you would have a fixed rake of the foil mast. This would mean discarding personal preferences and/or adaptation to local circumstances . Again, not practical.

You actually WANT to have the box be deeper than the DT fitting on the mast. That way you can ensure a full seat of both tapers. You do not want it to top out inside the box. That means movement and a broken finbox.

Yes, of course, a full seat means a fixed rake angle. This is what you WANT.

And yes, the forward rocking force is taken up by the front taper and back screw. If you rock, tighten, rock, tighten, rock, tighten, etc., several times in both directions, the front screw will remain tight during your session. Sailworks actually coaches this.

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segler said..
You actually WANT to have the box be deeper than the DT fitting on the mast. That way you can ensure a full seat of both tapers. You do not want it to top out inside the box. That means movement and a broken finbox.

Yes, of course, a full seat means a fixed rake angle. This is what you WANT.

And yes, the forward rocking force is taken up by the front taper and back screw. If you rock, tighten, rock, tighten, rock, tighten, etc., several times in both directions, the front screw will remain tight during your session. Sailworks actually coaches this.

Yes you WANT a fixed rake angle, but above all, you want YOUR fixed rake angle, adapted to your conditions and your board and foil combination.
marseille.glissattitude.com/blog/reglages-windfoil-le-rake.html ( you might want to run through google translate

also here :
and here :

and here :

Except when you're sailing in the one design IQ foil class : STARBOARD recommends "the top of the foil mast makes FULL CONTACT with the bottom of the boards foil box when fitted correctly. etc."
marseille.glissattitude.com/blog/iqfoil-settings.html

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segler said..
You actually WANT to have the box be deeper than the DT fitting on the mast. That way you can ensure a full seat of both tapers. You do not want it to top out inside the box. That means movement and a broken finbox.

Yes, of course, a full seat means a fixed rake angle. This is what you WANT.

And yes, the forward rocking force is taken up by the front taper and back screw. If you rock, tighten, rock, tighten, rock, tighten, etc., several times in both directions, the front screw will remain tight during your session. Sailworks actually coaches this.

That is not correct for all the boards. Phantom and Starboard boards have a box shallow enough so the mast head touches the top of the box. That is how they designed the box.

same with foil boxes with chimneys; maybe some old boxes with chimneys were not that reliable but boxes have come a long way since then.

the box of fanatic 2020 is much deeper :( I will put something inside

Yes, if you match brands of board and foil, it is fine for the foil DT top to touch the inside top of the box. They hopefully did all the fitting and engineering to make sure this works.

However, if you mix brands, such as Fanatic board and F4 foil in the picture above, you have no way of knowing how good the fit will be. Get a deep enough box and any DT foil out there will fit just fine.

I mix brands like a crazy guy. I use boards from Fanatic, Exocet, Mike's Lab, North Pacific, and Roberts, and foils from Moses/SABfoil, LP, AFS, and Slingshot. With deep enough boxes, everything fits. I absolutely reject the idea of the DT fitting touching the inside top of the box. That's bad engineering and is a path to a broken box because it enables movement. Unless, as said above, it is a matched brand.