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Paducah said..

The top is tied into the deck and provides a wider area to spread the load rather than point loading the front of the box when the foil wants to rotate.

But how much does a box or fin head flex? Not much I'd guess. Unless the fittings are manufactured to a tolerance within the flex range there'll be point loadings somewhere or other. A shim between the fin head and the deck would have to be made of rubber otherwise it'd either be a fraction too thick or thin.

If it is a go foil box it should be deep enough
the only ones to really watch out for are chinook. They call theirs a deep Tuttle when it is really only a medium Tuttle
Below are chinook go foil and horue

I must add
I have not use a go foil box for Windfoil so not sure if bolts line up

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Ian K said..

Paducah said..

The top is tied into the deck and provides a wider area to spread the load rather than point loading the front of the box when the foil wants to rotate.

But how much does a box or fin head flex? Not much I'd guess. Unless the fittings are manufactured to a tolerance within the flex range there'll be point loadings somewhere or other. A shim between the fin head and the deck would have to be made of rubber otherwise it'd either be a fraction too thick or thin.

Take a look at F4's (yes, the F4) comment here: www.seabreeze.com.au/forums/Windsurfing/Foiling/Open-iQFoil?page=2#30

OllyD,
What foil were you planning to use?,
As we now know you have installed a surf box
Cheers
Tony

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Paducah said..

Mark _australia said..
Agreed it should not bottom out, it's a taper lock. No Tuttle or power box fin should ever bottom out- it jams into tapered sides.

The people that actually build this stuff disagree. The top is tied into the deck and provides a wider area to spread the load rather than point loading the front of the box when the foil wants to rotate.

windsurf.star-board.com/products/foil-boards/ scroll down to "foil box"

"FOIL BOX
The Foil Box is larger and stronger than a normal fin box to distribute loads over a larger area. It is built using solid sheets of 20 mm thick high-density PVC with 8 mm thick carbon fibre walls, and has a flat, parallel bottom which allows the box to take both types of foil bases: tapered 'Tuttle-style' base and rectangular foil bases. In either case, it is strongly recommended for the front of the foil's base to reach the bottom of the box. This ensures that the vertical lifting load from the foil will be carried by both the front wall of the box and the bottom wall of the box."
The force is not directly vertical, it is forward trying to rotate the head in the box, the further forward the wing is the greater the rotating force.

Several shops sell shims to fill the gap between the box and tuttle head if one exists to either alter or fix the rake of the foil mast
By doing this you no longer have contact with the tapered sides & point load the front & back of the box & the mast head

Example: marseille.glissattitude.com/blog/reglages-windfoil-le-rake.html

Translation via google: Note. We recommend this setting solution without reserve on the floats dedicated to the foil, and which are fitted with reinforced boxes. Whether it is Flika or Cobra, we have experienced this solution for months in no structural problem. On the other hand, we have no hindsight concerning the use of a support at the bottom of the case on old slalom float cases.

Sidenote: Gutted for AUS 808 not my board or foil Too bad when they went off and made their own standard they didn't make it absolutely clear.

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AUS 808 said..

not my board or foil

Right you are. Sorry about that. Sympathies go to OP. OllyD

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obenebo said..
If the head of the mast doesn't bottom out, you can also pour in an epoxy spacer to fill the void.

I have on old Formula board with very deep Tuttle box, the head of the mast tapered and fit perfectly flush with the board, but left a few cm gap at top of the box. I drilled another hole between the screw holes, fitted the mast and screwed in (with plastic straws around the screws), then filled with liquid epoxy and solid balls shaped out of knead-it. The mast now bottoms out, is tapered and fits flush, and more importantly, shows no signs of weakness - yet.

This is the perfect way to use a spacer, fitted while the head is seated fully in the tapers so you get 5 full surface contacts.
That's the best it can get.
If the box then breaks it was simply not strong enough for foiling.

Compare that to 3 small points of contact when using an angled shim, simply no comparison.

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DarrylG said..
I must add
I have not use a go foil box for Windfoil so not sure if bolts line up

Daz, looks like 3 more boards on the way
Soon everyone will be riding FTY

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DarrylG said..
If it is a go foil box it should be deep enough
the only ones to really watch out for are chinook. They call theirs a deep Tuttle when it is really only a medium Tuttle
Below are chinook go foil and horue

Just FYI .... Chinook have never called theirs deep Tuttle. In fact it specifically says "not compatible with deep Tuttle"...

chinooksailing.com/collections/board-building-part-accessories/products/race-box

So what is starboard using in things like the Futura, it just says 'foil box' is that what they call their deep Tuttle or is it something else

Yes your right. It has been awhile since I have bought one. Much clearer now. I'm sure it use to be call deep Tuttle which caused the confusion.

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AUS299 said..
After spending the last week removing an old fin box from my formula board and replacing it with a Go Foil Deep Tuttle Foil Box. I am a little distressed reading this thread and wondering if I have completely wasted my time and made my board useless.

The foil mast is rock solid in the box however it sits about 10mm higher than it should be.

So my question is, will it work?

Will the loads be too much given that the full mast head is not supported. (70mm of the 80mm head is supported)

I am pretty comfortable with the construction method of the new box. I laminated the hole with 3 layers of 200gm carbon which is tied to the underside of deck. Shaped the high density foam and glued it in place before laminating over the box with 2 x 200gms carbon. The bolts were out by 5mm but new holes were drilled into the reinforced deck. I use a 5mm G10 plate to distribute the load on the deck of the board.

I had the same problem. Have a look at the corners on the tapers of the foil head. They were way too square to fit a deep tuttle on mine.

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Paducah said.. The people that actually build this stuff disagree. The top is tied into the deck and provides a wider area to spread the load rather than point loading the front of the box when the foil wants to rotate.

windsurf.star-board.com/products/foil-boards/ scroll down to "foil box"

"FOIL BOX
The Foil Box is larger and stronger than a normal fin box to distribute loads over a larger area. It is built using solid sheets of 20 mm thick high-density PVC with 8 mm thick carbon fibre walls, and has a flat, parallel bottom which allows the box to take both types of foil bases: tapered 'Tuttle-style' base and rectangular foil bases. In either case, it is strongly recommended for the front of the foil's base to reach the bottom of the box. This ensures that the vertical lifting load from the foil will be carried by both the front wall of the box and the bottom wall of the box."
The force is not directly vertical, it is forward trying to rotate the head in the box, the further forward the wing is the greater the rotating force.

Several shops sell shims to fill the gap between the box and tuttle head if one exists to either alter or fix the rake of the foil mast
By doing this you no longer have contact with the tapered sides & point load the front & back of the box & the mast head

Example: marseille.glissattitude.com/blog/reglages-windfoil-le-rake.html

Translation via google: Note. We recommend this setting solution without reserve on the floats dedicated to the foil, and which are fitted with reinforced boxes. Whether it is Flika or Cobra, we have experienced this solution for months in no structural problem. On the other hand, we have no hindsight concerning the use of a support at the bottom of the case on old slalom float cases.

Thanks for that it makes sense.

I guess it then becomes hard for a'non-handy' type person to get different brands to fit together..... might be a market for a cheap shim set.

EDIT - pondering how I'd make one as an exact fit for each box / board combo individually and it would not be hard.

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Mark _australia said..

Paducah said.. The people that actually build this stuff disagree. The top is tied into the deck and provides a wider area to spread the load rather than point loading the front of the box when the foil wants to rotate.

windsurf.star-board.com/products/foil-boards/ scroll down to "foil box"

"FOIL BOX
The Foil Box is larger and stronger than a normal fin box to distribute loads over a larger area. It is built using solid sheets of 20 mm thick high-density PVC with 8 mm thick carbon fibre walls, and has a flat, parallel bottom which allows the box to take both types of foil bases: tapered 'Tuttle-style' base and rectangular foil bases. In either case, it is strongly recommended for the front of the foil's base to reach the bottom of the box. This ensures that the vertical lifting load from the foil will be carried by both the front wall of the box and the bottom wall of the box."
The force is not directly vertical, it is forward trying to rotate the head in the box, the further forward the wing is the greater the rotating force.

Several shops sell shims to fill the gap between the box and tuttle head if one exists to either alter or fix the rake of the foil mast
By doing this you no longer have contact with the tapered sides & point load the front & back of the box & the mast head

Example: marseille.glissattitude.com/blog/reglages-windfoil-le-rake.html

Translation via google: Note. We recommend this setting solution without reserve on the floats dedicated to the foil, and which are fitted with reinforced boxes. Whether it is Flika or Cobra, we have experienced this solution for months in no structural problem. On the other hand, we have no hindsight concerning the use of a support at the bottom of the case on old slalom float cases.

Thanks for that it makes sense.

I guess it then becomes hard for a'non-handy' type person to get different brands to fit together..... might be a market for a cheap shim set.

EDIT - pondering how I'd make one as an exact fit for each box / board combo individually and it would not be hard.

I'd love a powerbox fin to Tuttle box converter. I know you'd have to cut of a bit of the front of the powerbox fin but the shim should be really easy. I really need to get a CNC machine or 3D printer.

OR everyone could just start using the same bloody box in their boards.

Making one piece fit another is a doddle for a machinist (relatively speaking). Even easier with a properly made mould.

This is why im fascinated that with all that already exists with fin heads and tuttle boxes, manufacturers still manage to make two totally different shapes that are meant to fit together. Did they never play with the shape puzzle in preschool?

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Ben1973 said..

Mark _australia said..

Paducah said.. The people that actually build this stuff disagree. The top is tied into the deck and provides a wider area to spread the load rather than point loading the front of the box when the foil wants to rotate.

windsurf.star-board.com/products/foil-boards/ scroll down to "foil box"

"FOIL BOX
The Foil Box is larger and stronger than a normal fin box to distribute loads over a larger area. It is built using solid sheets of 20 mm thick high-density PVC with 8 mm thick carbon fibre walls, and has a flat, parallel bottom which allows the box to take both types of foil bases: tapered 'Tuttle-style' base and rectangular foil bases. In either case, it is strongly recommended for the front of the foil's base to reach the bottom of the box. This ensures that the vertical lifting load from the foil will be carried by both the front wall of the box and the bottom wall of the box."
The force is not directly vertical, it is forward trying to rotate the head in the box, the further forward the wing is the greater the rotating force.

Several shops sell shims to fill the gap between the box and tuttle head if one exists to either alter or fix the rake of the foil mast
By doing this you no longer have contact with the tapered sides & point load the front & back of the box & the mast head

Example: marseille.glissattitude.com/blog/reglages-windfoil-le-rake.html

Translation via google: Note. We recommend this setting solution without reserve on the floats dedicated to the foil, and which are fitted with reinforced boxes. Whether it is Flika or Cobra, we have experienced this solution for months in no structural problem. On the other hand, we have no hindsight concerning the use of a support at the bottom of the case on old slalom float cases.

Thanks for that it makes sense.

I guess it then becomes hard for a'non-handy' type person to get different brands to fit together..... might be a market for a cheap shim set.

EDIT - pondering how I'd make one as an exact fit for each box / board combo individually and it would not be hard.

I'd love a powerbox fin to Tuttle box converter. I know you'd have to cut of a bit of the front of the powerbox fin but the shim should be really easy. I really need to get a CNC machine or 3D printer.

OR everyone could just start using the same bloody box in their boards.

There is a company making them but it only fits deep tuttle not Chinook etc. They built them for FS boards that guys also foil on.

I'm 100% with you on a universal box design but until then I think DT plus some adaptation could work. I'm about to start machining an insert to take slotbox fins in a DT.

If you look here,

www.seatexboards.com/carbon-deep-tuttle-fin-box-v-2-on-sale/

or google "deep tuttle finbox" and look at the pictures, you will see that there is a lot of variation in wall thickness. In general, those with thicker walls, and/or extra reinforcements, are foil ready.

The custom foil board builder I know in Hood River uses a thick-walled reinforced deep tuttle finbox for all their foil boards, without exception. (They even add 16" long stringers running forward to add strength for the cantilevering forces exerted by foils.) What they do is cut off the top of the box so that there is no roof, but there is a gap between the inside of the top of the box and the bottom of the top deck of the board. The top deck of the board is greatly reinforced with extra carbon and glass to carry the loads of the fender washers on the fin screws. They do not make screw tunnels like you see on some boards. They consider such tunnels anathema. Cheap and weak.

When I bought a foilboard from them last year, they made a HUGE point of this thing about leaving a gap between the top of the foil fitting and the inside bottom of the board's top skin. They emphasized that you MUST get a tight locking fit to the tapers, and nowhere else. (Parallel sides, of course, too.)

With the gap it is possible to fit different foils to the same box since all foils (and fins, too) have various fitting heights. AFS and Moses, for example, have really tall fitting heights, while LP and Power Box, for example, have a shorter height. They all fit perfectly since they all lock to the tapers and stop there, with whatever gap is remaining. All of this is true, also, for formula fins.

I've installed one of the "tunnel less" foil boxes and I agree it's much stronger, when used with wide washers, because the bolts pull directly onto the vertical walls of the box.
I have a couple of older Roberts slalom boards which use boxes like this and I'm confident they will manage a foil without complaining.

I just want to thank everybody for their contribution to my 'deep tuttle' education.

In the end I took the least expensive fin and cut it down to fit. I got it to fit perfectly after quite some grinding and sanding.

This gave me confidence to do the same to the other 2 fins and they all now fit beautifully.

The box fitted is not deep tuttle, I'm pretty sure it's a surf box judging by the dimensions posted earlier in the thread, but for my purposes I think I have a perfectly sailable solution.

I think the main reason I was able to get the bolts aligned was because the box doesn't come up to the top skin of the board, rather, the top bolt holes are recessed deep into the board with only a relatively thin carbon plate through to the fin box. Had the bolt holes travelled from the top skin down to the fin box I don't think the bolts would have aligned with the fin threads.

I'm assured this box is stronger than the deep tuttle the board came with, and it was fitted by guys who foil themselves, so I'm hoping the pressures from using the fins will be fine, and hopefully so will a foil should I decide to move in that direction in the future.

Here are some pics of the first cut down fin held against the uncut deep tuttle fin just for interest -