Not to go bashing Starboard, just posting in case someone encounters the same issue I was having when my Supercruiser arrived.

2019
starboardfoils.com/pages/technology-201
The Starboard's mast head is designed to fit into boards that either have Deep Tuttle fin boxes with a sloped bottom inside or the newer Foil Boxes that have a flat bottom inside.
The elongated holes allow the bolts to rotate and adapt to both angles: parallel or tapered.
The stainless steel nuts are oversized and deeply recessed into the head for maximum strength

2021
starboardfoils.com/pages/2021-assemblyguides
2 in 1 FOIL BOX FITTING TIPS
Our Deep Tuttle Masts are flat on the top to fit foil boxes that are also flat-bottomed.
This guide shows where to cut to fit foil boxes that have sloped bottoms.



So as per the "2 in 1" fitting guide I trim the mast head along the lines to fit my sloped foil box (Deep Tuttle)
* Note how Starboard says MOST foil boxes have a flat bottom...

After a lot a fiddling to align the bolts I noticed that the front hole is indeed elongated so the barrel nut can rotate for my Deep Tuttle box. The back barrel nut instead could NOT adapt for this angle! The hole is not "elongated" and the back bolt can not enter parallel with the front bolt.

So I than drilled out the back box hole of my board to give a bit more way forward and with a spare barrel and a new bolt I almost manage to align the bolts, although not parallel.
Finally the back bolt broke in the barrel nut when loosing it again. (I used a 3mm left hand drill bit to get it out later)


I contact Starboard and they replied quickly:

Select to expand quote

The changes occurred between originally adapting foil masts to what was more common in Deep tuttle fin standards on boards and eventually realising that the flat top foil box worked better for fit and strength so this became the more commonly used standard moving forwards.

Regarding the issue with the rear bolt insert not pivoting on the Alu V5 masts, this is an unfortunate result of needing to reinforce this area due to prior strength issues with this mast. Earlier generations of this mast did have pivot at the rear bolt, but as a result of how this was built in, there was insufficient metal around this area and with a lot of sessions the area would weaken and sometimes break entirely. So to reinforce, we increased the amount of metal around the 12mm insert, but in doing so lost the option for the rear bolt to pivot. As these masts are primarily used with iQ boards and other Starboard foil boards, where the boxes are the flat top version, the inability for the updated rear bolt insert to pivot generally isn't a problem, with most boards used.

For your case, normally expanding the tail side of the rear bolt hole with a drill bit, by around 4-5mm, should be sufficient to allow the bolt to travel down and insert properly in the 12mm rear barrel nut

So that is what I did, with a 6mm drill bit, working very slowly at low revs I pulled back and elongated the back hole.
Attached a few images

Yup.
I prefer twin track.
Tuttle fins I have don't fit my different Formula boards. Talkin deep tuttle.
Regular shallow tuttle seems to interchange with only sanding or filling the sides.

Yeah I understand the (Deep) Tuttle Box specs are not always respected, is there even a defacto standard?

I had to do a lot of sanding with 40-60 grid to make it fit but better having to sand than fill.

[enter bashing mode] I was just baffled Starboard did not allow the back barrel nut to rotate to allow for the "standard" Deep Tuttle shape. Basically what they are saying is get a Starboard board.
Having to hack a brand new product with a drill is not what I had in mind to be welcomed onboard.. Starboard[/exit bashing mode]

After all I have heard about SB, and seen in person, would not think of getting a foil from them. However, I do recommend AFS foils, built to last and take major impacts without damage.

Back to my traditional and tiring soapbox about DT boxes.

If you mount the DT head such that the ONLY contacts are the front and rear tapers, it doesn't matter what the inside roof of the box is since it will not touch; it's not supposed to touch. This is what the engineering design by Tuttle was meant to achieve. The bolt angles are tied to the taper angles. The top surface angles and inside roof angles are fluff, and not intended to touch. We went through all this for years during formula racing days.

As shown above, I did have to cut down the rear end of a DT top once to get a AFS foil to fit into a Exo FF 132 box. Since I made sure ONLY the front and rear tapers are the touch points, the angles of the bolts are still correct.

Thanks for letting us know about this
Yes it can be hard working down inside the mast tuttle head with hand tools
At the starboard factory with the right gear it would be sooo easy to fix this
Be sure to open out hole a little past the barrel nut at the new angle so if the bolt passes on further it does not hit a dead end
Cheers
Rod

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FFish said..
Yeah I understand the (Deep) Tuttle Box specs are not always respected, is there even a defacto standard?

I had to do a lot of sanding with 40-60 grid to make it fit but better having to sand than fill.

[enter bashing mode] I was just baffled Starboard did not allow the back barrel nut to rotate to allow for the "standard" Deep Tuttle shape. Basically what they are saying is get a Starboard board.
Having to hack a brand new product with a drill is not what I had in mind to be welcomed onboard.. Starboard[/exit bashing mode]

It's not a Starboard thing with the Boards. It's every board built in the Cobra factory - which is almost all Windfoil boards except customs.

So while there IS a deep Tuttle standard, really the standard is whatever Cobra says it is.

I kindof disagree. The DT standard is what Tuttle put out on his design drawing. What really matters are the taper radii and angles, and the bolt positions and angles. The drawing does not specify a particular height.

We used to see a huge range of heights in formula fins, everthing from 1 inch to 3 inches. Now we see a big range of heights in foil top fittings. All of these comply with the design drawing regardless of height.

Since the heights are variable, there is no design intent for the fitting tops to touch the inside of the box roof. The design intent is for a tight fitting of the fore and aft rounded tapers, and nothing more. This tight fit will lock in the rake and bolt positions.

If the Cobra tuttle boxes are too shallow for a particular foil, well, too bad. They still comply with the design, as far as I can tell. I have measured inside box heights of 1.6 inches to about 2.8 inches in different Cobra-made boards. We all have to make our equipment fit together. It's up to us.

When I did not have a foil mast head shim to fill in the triangular space between the mast head and top of DT/foil box, the rear mast head screw was always loose after a session. When I use the shim, the rear mast head screw is snug but not as tight as originally (probably due to hard rubber washers compressing a little). So for me a mast head that bottoms out in the box while sitting in the tapers, is better than one that just sits in the tapers. But then the physical definition of a DT box would have to be updated, and those dimensions would have to be very precisely followed.

In my 4 years of foiling, if a finbox bolt (or screw) was ever loose it was the front one, never the back one. That's because the front wing, which does all the lifting, is located forward of the foil mast and tends to rock the whole thing forward, pushing up on the front bolt. (This is also why the front bolt on a SAB mast to fuse connection tends to work loose. You have to really watch this and keep your hex key handy.)

If the back finbox bolt is loose, it has to be because the foil was not completely seated in the first place. Or because the foil hit something in the water (such as a manatee, or the bottom).

All of this speaks to the wisdom of including a flange on the DT top, such as that found in SS and SAB-aluminum-mast, and LP, and a few others. Assemble to flange-tight and forget it. Nothing will work loose.

fwiw, Starboard doesn't call their box a tuttle, deep tuttle, etc but a "Foilbox". Think of it as a software fork. It came from a DTT but is meant to address slightly different needs/forces, etc as they see them. There is sufficient backward compatibility but there always going to be cases where not every older board works perfectly with the new standard. They are worried less about backward compatibility and more about not having warranty claims for the hundreds if not thousands of foilboards they will be selling in the next few years. Anyone doing IQFoil training is sailing their board harder and more often in a year than some of us will in a decade.

iqfoil.star-board.com/wp-content/uploads/2020/10/iFoil-Board-Trimming-Guide_iQFoil95.pdf
"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 video they link:

Yes, matching foil brand to board brand, and especially IQ to IQ, will always guarantee a good fit.

Most of us who do not race need to usually fit brand-x foil into brand-y foil box. So, to make this work, just depend on the tuttle design intent, make sure your foil is not too tall for the box inside height, fit tight to the front and back rounded tapers, and you're good. The tapers carry the vertical loads just fine. You don't need inside roof contact for that.

Flanges are even better. Yesterday in Hood River I saw a used AFS foil where the flange ran only around the front half of the DT fitting. That's smart since the front carries all the up forces from the front wing.