Tuttle Box vs. Dual Track Cassette for Foil Mount

[Beasho]

Here is a write up from BigSeppo on the SeaBreeze forum.  Consider this a consumer insight report:

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I've been foiling a ton over the last six months. I'm loving feeling like a grom again.

Big thanks to Piros and everyone for sharing their knowledge. And some local pros who are world class, watching them fully load up the foil on turns is just inspiring. It's a good time to be a foiler.

The thing is, I have gone through a ton of foil gear. I probably have 8 wing sets and a number of boards from various brands. Much of it has either broken or has performed poorly (and "poorly" is an understatement in some cases).

I am a really big dude, riding big foils in small surf. It's a lot of forces at work. So gear that might be just fine for a normal sized dude strengthwise is not fine for me. . . . . . . . .

As a big guy, I would strongly recommend getting a dedicated foil board once you are ready to move on from the X32.

Think about it... We are around 100kg, flying through the air, balanced on the head of a pin. That pin head is where the mast meets the board.

The forces are enormous on that point. It has all your weight in the air. And it has all the forces of the foil.

We need that point to be as strong as possible.

I have ruined a number of boards learning this lesson.

Sometimes it was the box that wasn't fully reinforced from deck to bottom from the manufacturer.

Separately, with a foil plate, you are at the mercy of what is under the skin of the board... The plate itself can be strong. But my experience as a big guy is a fast delam between the foam and board skin. Board is ruined. Usually on Day One.

The board just flies wobbly with the plate. Then you get to the beach, and realize the bottom of your board is ruined.

That even happened to me with a plate on an extremely expensive, bomber construction Quatro custom built full carbon sandwich SUP that cost me a fortune. It broke down the the PVC (or whatever you call the hard foam material in the sandwich). That's when I realized that the plate isn't going to work at my size. That is one of a number of boards I ruined.

The Blue Planet Easy Foiler flies so solid. I know the box is reinforced "right" because I've experienced (and killed) so many boards and products that were no good. And soon ruined.

The R&D on the Blue Planet was properly done on placement of the box and reinforcement of the box. That rigid connection actually makes the board highly responsive.

Again, I have no relationship with Blue Planet, I paid retail, etc.

You can buy any brand. I would just recommend as a big guy getting a dedicated foil board if possible.

Hopefully the brand did the proper R&D, the box is solid, and is placed in the optimal spot. The forces we put on a board are great.

This probably won't be an issue on foil boards in a year or two. Nobody wants to deal with warranty issues, bad press, and such.

For now, I like this board.. A lot.

In your case, have fun on that X32! Don't stress about it too much! Enjoy being a grom again! It's the best part of the learning curve.

When it's right to move on, make sure the box is bomber. Then you don't have to go through what I did. You don't want to, I promise!

[Beasho]

I am partial to Tuttle Boxes having used them for 20 years because fin boxes in Windsurfers universally failed. 

That said I have also had my Tuttle Foil Box ripped out of my board after a Professional Installation.  This was a result of a 12 foot lip coming down directly on my board.  I have since re-installed and have a few hundred successful flights and counting. 

BigSeppo's Post was originally here:

https://www.seabreeze.com.au/forums/Stand-Up-Paddle/SUP/Finally-a-good-foil-board?page=1#5

[starman]

Beasho I'm a bit confused, the BigSeppo post talks about Tuttle Boxes and foil plates (i.e. stick on mounts). I don't see his post speak to Dual Track mounts.

I don't see the Tuttle being any stronger than the Dual Track Cassette. The Tuttle has been around a lot longer so no surprise it was adopted by most of the foil builders.

The Dual Track does have an advantage of being adjustable fore and aft.

Those stick on mounts are as described by BigSeppo, a delam waiting to happen.

[surfcowboy]

Yes, that's what is wobbly. He talked about delaminating the board with a stick on.  Not dual boxes mounted in a cassette.

Blue Planet will ship all boards with both dual track and Tuttle as of Feb.

[PonoBill]

Hard to believe anyone thinks a stick-on plate is a good idea. You'd be better off wrapping a plate mount with fiber-reinforced tape. Use up a couple of rolls and you're good for at least as long as the lamination will last under a stick-on.

Tuttle boxes are used for foils because of inertia, not design superiority. Windsurf foils preceded SUP foils by years, and they all got stuck into existing Tuttle boxes. That's why windsurfing foils have long fuselages. The only surprise is that SUP foils don't have long fuselages too. At least people figured out they didn't have to stick SUP foils back where the fin used to go.

Attachment methods could be modeled in Fusion 360 and analyzed for stress and yield strength, but here's what I predict the model would tell you. That the strongest way to attach a foil to a board would be through-bolting with glassed-in reinforcement tubes and a backing plate. Second strongest would be properly installed, glassed under mast tracks. Third would be Tuttle. N+1 would be a stick-on plate. The only way mast tracks would be weaker than a Tuttle is if the tracks are too close together and the bottom is weak. The big benefit of mast tracks is beam strength. A Tuttle can be viewed as a reinforced tube and could therefore be potentially as strong as mast tracks if it is effectively joined to both the top and bottom of the board and is placed in a big enough PVC cartridge to distribute force to a large amount of bottom and deck area as well as engage a sufficient amount of EPS to provide support. One pound EPS has a compressive strength of about 15psi. You need a lot of area for that to be meaningful, but it helps.

Gluing a Tuttle in and glassing over the bottom is weak. A lot of the Tuttle mounts I've looked at leave me wondering why they haven't already failed.

[Stoke]

I had about 30 days on a stick on plate mounted to an FCD shortboard. It looked questionable but was surprisingly solid for me. I was using a gofoil and didn’t love the tuttle-plate adapter. I have about the same number of days on a tuttle box setup that was built into my heavily glassed XTR construction board. I have taken some hard falls and it is totally solid. The hardest falls for me are those where I cavitate flying too high at speed (usually in chop) then “trip” and land nose down with my weight on the board. I have to imagine that is a lot of load on the box. I’m 175lbs, so not huge but not small either.

The Tuttle and dual track setups are probably both solid as long as they’re installed right. FWIW, I think the decision should have more to do with matching the attachment method of your foil setup. Agree with the benefit of fore/aft adjustment with the tracks.


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[surfcowboy]

I'd agree on the bolt through Pono, 2 skins would be better but spreading the load has got to be key as well. I suspect that's how the stick ons survive at all.

In the end, everything works, until it doesn't. When a crash that hits the point of failure comes is the variable. The force required to fail doesn't change it's just sitting there on the horizon until you push up to it.

I saw something interesting the other day, I went to try to pull up a stray glass thread that had hardened and pulled up a little 1cm section of the glass I'd just laid down off the bottom of my board near the edge. Reminded me that the adhesion onto old glass is not as great as when you're building the board. I definitely want to build a board fresh for foiling if I like it at all. Add-ons are weaker than integrated structures. It also reminded me to get that epoxy nice and warm for a few days before I go hopping onto it once I'm done.

[supuk]

At the end of the day both styles can be made to work and a lot of the time it comes down to how they are installed in the board and the quality/density of the foam they are being installed into.

The Tuttle boxes are nice as they get installed top to bottom so good on lateral loads but only if you have a good amount of bonding area to the actual carbon of the Tuttle box itself. With the vertical loads they are relying only on the shear strength of the top and bottom skin when over a very small area unless you add extra glass to tie them together but negatives are there is no room for adjustment in for and arf or angle of attack.

Generally Duel tracks with inserts strength mainly relies on spreading the load over a lot larger area, the larger the HD foam insert the better the load will be spread, if the board is made of extra light weigh 1lb foam you can just use a thicker insert or even go all the way to the deck if you are really concerned. Again good installation is key and tying it in to the bottom lam so lateral loads are working in both compression and tension on the skin as well as the compressive loads spread over the foam. The duel tracks probably have a little more drag as they are not as clean as the Tuttle mount but they offer you the ability to change mast position and angle of attack if you need to. 

[Newps]

I like the dual track cassette option better.  Working on getting the two I bought into some foil specific boards.  Going to try these in prone specific boards for testing. 

I've been using a tuttle box for about 9 months.  It has been for the most part bullet proof. 
Negatives
- A lot more work
- Costs more to install (correctly, subjective) as a retrofit into old boards. 
- Tuttle box retrofit adds a lot weight. (At least with my board).

Positives
- Tuttle box retrofit, board's bottom contours remain mostly unchanged.  If you don't mind the extra weight, you can still ride the board as a regular SUP. 
- AOA is easily adjusted with a Tuttle Box as long as the foil's mast and fuselage are two separate pieces and shimmable. 

[Beasho]

Beasho I'm a bit confused, the BigSeppo post talks about Tuttle Boxes and foil plates (i.e. stick on mounts). I don't see his post speak to Dual Track mounts.

 
No more confusion BigSeppo clarifies:

Dual tracks:  A delamination waiting to happen if the tracks are only mounted to the bottom skin of the board:
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Just to clarify, I have had total failures on twin mast boxes installed by foil board manufacturers.

Piros and Robert from Blue Planet have seen pictures of one of these failures.

The manufacturer did have the two "fin boxes" set into a high density foam box. But the high density foam did not go from bottom to deck. So the separation happened as the high density foam rubbed up against the "beer cooler" foam, and delammed on day one. Standing on the beach, you could push on the foil and see the bottom of the board deforming each way you pushed it. The high density box was unattached from the EPS foam. (Don't want to flame out the manufacturer, they made good on things.)

I bring this up because there's some discussion of this over on StandupZone.com, saying the twin mast boxes might be superior to the tuttle.

www.standupzone.com/forum/index.php/topic,32989.0.html  (This Post)

I don't have a dog in the fight. Just wanted to point out that I have killed twin-mast-box boards, actually way easier than tuttles.

Piros has said to me that, regardless of box style, the high density foam should go all the way through, and that both the deck and the bottom should be reinforced.

The boards I've had that follow this thinking have held up. The others have not. It just so happens that my boards with tuttle boxes have this type of reinforcement. So tuttle has been better for me.

But I think it's about Piros's idea, not necessarily about the tuttle.

[surfcowboy]

I can see it. I'm about to find out, but hopefully at my size and being a beginner I won't find the limits too soon.

I think some sort of wood or other sandwich skin is likely needed longer term for heavier use. If I build a dedicated foil board I'll probably insert HD foam all the way through as well as figure out a skin at least for the couple of square feet around the box.

One thing for sure, we will all find out soon enough.

[PonoBill]

This will eventually sort itself out, the technical solutions for the strength of attachments to surfboard-like structures were solved long ago building windsurfers. Neither mast boxes nor Tuttle fins blow out the way they used to. Construction for a surfboard is cost-constrained and the majority of boards are sandwich construction only in marketing terms. The only real sandwich construction surfboards (meaning PVC foam between two composite skins) I know of are Jimmy Lewis. A Tuttle box installed connecting top to bottom of a sandwich construction board will hold until the board breaks in half--it will be stronger than the surrounding board. Likewise, mast tracks in a PVC cartridge bonded to the sandwich top and bottom will be much stronger than the board. The issue is not really which attachment type is strongest, it's how the attachments are installed. A simple composite skinned EPS foam board with either a tuttle or mast tracks attached only to the bottom skin is extremely weak. If it holds up it's only because it hasn't been stressed.

I'm reasonably sure the L41 board I just installed my new GoFoil to would crumble like a graham cracker in a serious wave or with a bottom strike if I hadn't done the reinforcement I did. Two mast tracks in a PVC cartridge that extends top to bottom with a large carbon patch top and bottom. Later I installed a Tuttle in a cartridge that already had a carbon bottom surface. Bonded that to the mast tracks on either side as well as the top and bottom of the board and did an additional CF patch on the deck. I consider this a minimum installation for a single skin board.

As everyone is probably aware, there is no AOA adjustment feasible with a GoFoil, so unless I add an adapter I'll just have to go with what it's got.

Headed out to play now. The low wind/4-5 surf that was supposed to be at Kanaha isn't. So I guess I'm going to be driving a bunch.

[surfcowboy]

Just finished the carbon layer on my bottom and it's staggering how weak the glass feels next to bagged carbon. Now I'm wishing I had put pvc all the way to the deck but at 130 lbs I'm hoping I don't put too much strain on it.

Now that I've done this I can see doing a carbon bottom and deck patch on my next foil board for sure.