Had to trim my Starboard Foil Mast head and now I have a problem

Hey folks! I have a Starboard C400 Carbon 95 that I was using on my JP Hydrofoil 145L. To use it on this board I had to trim the mast heads just as Starboard recommended, so it could fit properly (Picture below). Now I sold my JP board and I bought an IQ Foil board, which requires a flat top. Wondering if anyone had the same issue and what is the best way to make it compatible (and safe) again. Looking forward to your recommendations.Thanks,Felipe

AFAIK, the foil head is supposed to sit on the top of the box in the iQFoil. If you have that piece of mast you trimmed, you could just glue it back with epoxy. Otherwise, you could glue a piece of plastic. But I don't think you will have any issues using it as is because the front bolt is the one "pushing in" and sitting on the flat surface of the head. I have the IQFoil mast but my board has a very deep box so the foil is only supported by the tapers.

Select to expand quote

Subsonic said..
You don't need to fix it. The tuttle shape will lock it in position. It is possible to make a shim to fit, but it is time consuming, and not really necessary.

Thanks Subsonic. My concern is that it is a significant gap and the load will not be distributed correctly.

Select to expand quote

WillyWind said..
AFAIK, the foil head is supposed to sit on the top of the box in the iQFoil. If you have that piece of mast you trimmed, you could just glue it back with epoxy. Otherwise, you could glue a piece of plastic. But I don't think you will have any issues using it as is because the front bolt is the one "pushing in" and sitting on the flat surface of the head. I have the IQFoil mast but my board has a very deep box so the foil is only supported by the tapers.

Thanks Willy. Unfortunately I did not keep the old piece. Big mistake.

Select to expand quote

mareks360 said..
Unfortunately, to my knowledge Starboard has only made the replaceable part for aluminum masts that can be replaced after trimming.
Look for "Starboard Foil Hardware and Parts - DT Spacer". It was only $5 at Boardsports California when I bought it.
It is still there:
Starboard Foil Hardware and Parts | Boardsports California
boardsportscalifornia.com/product/starboard-foil-hardware-and-parts/

See picture and the description.

I guess it is better to make your own spacer fully filled because the one for Aluminum Mast only had support on the rim.
See the picture on the website to see what I mean.

Thanks! I got your point, and that's right, I spoke to a distributor and there isn't a spacer for the Carbon mast.

An idea that came to my mind is to get any of the "tuttle to deep tuttle adapters" trim it and glue it to the mast head, as you and Willy suggested.

Select to expand quote

fmlacerda said..

Subsonic said..
You don't need to fix it. The tuttle shape will lock it in position. It is possible to make a shim to fit, but it is time consuming, and not really necessary.

Thanks Subsonic. My concern is that it is a significant gap and the load will not be distributed correctly.

WillyWind said..
AFAIK, the foil head is supposed to sit on the top of the box in the iQFoil. If you have that piece of mast you trimmed, you could just glue it back with epoxy. Otherwise, you could glue a piece of plastic. But I don't think you will have any issues using it as is because the front bolt is the one "pushing in" and sitting on the flat surface of the head.

My mate Madlad has exactly the same setup. An iq foil mast that has had the head trimmed, and he's using it in a board that has a full sized (flat top) foil box. No issues the whole time he's been using it, which is years. Everyone has now also taken to shimming at the front screw, and we aren't hearing of any catastrophies. As WillyWind said, it's the front end of the foil head that carries all of the weight when foiling, regardless of whether the foil head is all there or not (as well as the tapers of the foil box). Starboard have in their wisdom left a flat section at the front, so no proper point loading.


having said all that, if you really want to have the gap filled, it's not too hard to make one if you're half way handy, it's just a little time consuming. Once upon a time when I had a foil that had a pointy head on it that was actually going to point load the front corner of the box, I made one out of fibreglass by building strips of it up layer upon layer, then cutting it down into the approximate shape, then finish it off with a block and sand paper. You just need to follow the lines/tapers and curves of the foil head where it's going to fit, and sand it bit by bit until it matches. If you're not too keen on building a fibreglass one you can do the same process if you can find a hard but sandable compound of some sort..

Select to expand quote

An idea that came to my mind is to get any of the "tuttle to deep tuttle adapters" trim it and glue it to the mast head, as you and Willy suggested.

or you could sacrifice an old g10 or carbon fiber fin head to make the shim with it.

Well, Sometimes it is good to think what an "Objective Allien" from Outerspace would Rationally Think about the Technical Problem and Filter all the Emotional Factors and Human tendences and weaknesses.
There is lot of Scientific Psychological Studies on Human Behavior the Even the most Rational People would say something Irrational just to fit in or because a lot of People said something before "like looking at black saying it is white".

Unfortunately (or Fortunately) my "internal compass" and "my loyalty to the Truth" is stronger and more important to me than upsetting some of my Friends of different opinion.
To me, you gain the Respect when you have "loyalty to the Truth" no matter what the consequences.

Having this above in mind and my Deepest Care for Wellbeing of fellow Windsurfers /Windfoilers here are some Facts:

I have done Everything Right and even more than Right:
Having 2013 Starboard FW (Formula Windsurfing) Carbon IQ 167L Board I did a custom shim to completely fill the gap therefore complete load was supported by tapers AND the top surface of the Deep Tuttle Box.

Guess what happen ?

Tapers cracked and the custom shim pushed the decking up:




I posted a complete Report with pictures on NW Windtalk in October 2021:

"What do you need to know before considering Formula Board for windfoiling - in particular when you are heavyweight"
groups.io/g/nw-windtalk/topic/86018071

Therefore someone can "Preach" as much as someone wants how it never happen to you. I understand. The important part is to examine the facts and calculate risks Individually for Yourself.

In my case additional risk factors are:

1) Being "Heavy Dude" in speedos over 200LB (~90kg) but in gear with backpack, paddles, 2L camel water pack, winter wetsuit etc, etc adding up to over 220LB (100kg)
2) Using M1000 Wing (the largest race wing at 100cm span and 1000cm2 surface)
3) 115+ Long Fuselage (in this board), BTW you know I use 115++ on the SB Go 180L & 200L (and why) but there I use 75cm mast that has a flange and 1000s of miles - no issues.

Simple Physics: Weight and Lever.

Select to expand quote

Awalkspoiled said..
That's a nasty result, Mareks! Is there any chance you might have overtightened those hex-head bolts? That could contribute to the tapers' cracking and once the front and back of the box are busted the rooftop support is definitely going to give way even if it fits perfectly.

If the shim doesn't fit perfectly - just a hair too tall - over tightening will crush the strength of the roof also before the tapers can take the load. I don't love Allen, Torx or Phillips-head bolts but they are much harder to overtighten.

I do not think so. I have a lifetime experience of fixing cars as my other hobby e.g. Fords (Falkon in Australia, Tauruses in US) and GM Corvettes. When I tighten the bolts with Starboard Foil (M6), I use my fingers around ratchet head, therefore I do not use the lever.
This way I make sure it is never overtighten. On Slingshot Foils (M10), I use cordless power drill (because I use extra long bolts) on a proper torque setting but then it does not matter because Slingshot has Flanges therefore the board is sandwiched well between my large plate on the top and the flange on the bottom. You might have seen it on the pictures in my earlier posts.

I think there is probably another factor to consider: Wear and Tear.
Greg M was commenting in details on NW Windtalk when we discussed it with our local Pacific NW Foiling Team back in October 2021.
The link I provided earlier.
The board I bought from our local Champ Darius L. Who put a decent amount of miles but at his much lighter weight ~160LB (73kg) also with similar Race Foils.
There was no visible damage or cracks but you know how it happens with bolts.
You can only see the pattern of weakening after bolt already snapped.

BTW There might be even one more contributing factor I show in the link on NW windtalk with pictures.
Starboard Foil mast to fit Legacy DT in Formula Boards has to have its barrel nuts rotated so the bolts fit the top deck holes.
When the same mast is used in a Foilbox, these barrel nuts are at 90 degree angle so the forces are only UP Down.
Here is the picture:

Keep in mind EVERY foil board producer recommends that you make contact between the foil head and roof of the box. Most even make shims to adjust rake.

Truth is that foil loads are a completely different direction to fin loads.

That said all the load is on the front of the foil head so your current one is just fine.

It was said above: "Keep in mind EVERY foil board producer recommends that you make contact between the foil head and roof of the box."

Uh, no, they don't. I know that Roberts, Mike's Lab, and North Pacific do not espouse this. Sailworks, who sell Roberts and North Pacific, do not espouse this. They all espouse intimate non-moving contact of the tapers. Sailworks even coached its customers to rock the foil back and forth while hand-tightening the screws until there in no more movement. After 5 years that has worked for me without a single box failure. For the past 3 years I have been running a SABfoil in a Fanatic board without problems.

If you match brands, such as, for example, Fanatic board and Fanatic foil, sure, go ahead and get inside roof contact since they designed their gear that way.

If you mount the foil into the DT box such that it can move fore and aft, you're asking for trouble. You will split the fore and aft ends of the box. Inside roof contact--if not actually designed in with brand matching--enables this movement.

This is just common sense engineering. The front taper, which is all of 3 inches long and 1/2 wide, takes ALL the rocking force exerted by 230 pounds of rig and rider. This is a massive force multiplier. If that force includes an impact from a moving foil fitting, it ain't gonna last long.

Or a foilbox, which through extra width and re-enforcing provides the required support to stop both the added leverage rocking the box out, and stops the added upward pressure of foiling from splitting the tapers.


mareks formula board was lacking a foil box.

A Tuttle fin box is designed to take loads on front and back tapers.

A Foil box uses a lot of the same dimensions as the fin box but is designed to take the loads on the roof of the box.

Pretty simple but some people keep getting confused.

Hey Grant, I don't have any evidence of my own? What do you call 5 years of no problems? What do you call Roberts, Mike's Lab, and North Pacific designs and builds? What do you call Sailworks instructions? If I'm backed into a corner I am happy to be there just foiling away into the sunset without gear failures.

A "foilbox" is nothing more than a deep tuttle box with a specific added feature of roof shape and depth and reinforcement to fit the "same brand" foil. My Fanatic and Exocet boards both have "foilboxes," but I run them with SABfoil and AFS that do not contact the inside roof.

But like you have been saying for a long time, the only real solution to all this is the twin-track, which everybody should be going to.

I guess twin tracks is overall heavier, definitely more drag before flying, and racers don't really need a lot of foil mast adjustment that cannot be obtained from shimming, I guess.