Select to expand quoteZeroVix said..Ian85 said..
I have been using a spacer in Formula Boards. A Mistral Devil has recently started blowing bubbles around the Tuttle box finscrew holes. No sign of damage but heard a noise like carbon crunching while foiling through a boat wake. Originally used with the NP pinky (maybe 30 times) . Recently upgraded to the SB Alloy Race Plus. Now using a SB HWR Formula (5 times) , that is showing signs of the deck being pushed up at the front screw hole. This suggests that the foil is not fully seated in the tapers, thus the spacer is too big and via the foil head is pushing on the top of the box. Note. I do use a lanyard tied from a footstrap to the foil as a security measure.
I am going to take segler's advice and run without the spacer, ensuring the tapers are fully seated.
Then follow fjdoug's advice and source/fit a replacement foilbox. (Or possibly a new foilboard.????
Any recommendations on a replacement foilbox and where to purchase. I know about the ones from Seatex in Italy. $450?.
Thanks.
Ian
I don't know of any other place for a good foil box. If you send Seatex a PM (member on forum), they will send you a discount code. Not much discount and shipping cost are high. I haven't installed mine yet. The box isn't a true deep tuttle (angle). It is a reinforced parallel box with 69-70cm depth. A lot of $$, but what are your options for a good box?
There is a DT box called King Tut that is supposed to be over built for foiling and costs $125, www.kingspaddlesports.com/products/deep-tuttle-box
The 80 degree back tilt of the front rounded taper, and 80 degree front tilt of the back rounded taper are plenty of structure to carry both the up and rocking forces of the foil in the finbox. Don't need any kind of contact along the inside of the top.
The genius of Tuttle's design is that a deep finbox can accept fittings of various heights without compromising strength. Just look at his drawings to see this. His finbox goes up to 5 inches deep, while most fins and foils have heights ranging from 1.5 inches to 3.5 inches.
If you absolutely must fill in the top to get a load carry inside the finbox along the top of the foil, then you are committed to using just one foil for that box.
I use three foils for one finbox. They all have different heights, they all fit in nice and tight to the tapers, and they all work perfectly.
Why limit your options when you don't need to?
I agree for slapper-only use the tuttle design was perfectly adequate since rake was not (that) crucial.
The moment you install a foil in the tuttle design , - which, all things considered, was never it's intended purpose nor design - things change since rake of the foil mast is critical for the combination to work properly.
Surely, you can just go ahead and hope the taper of your foilbox and foil to match and give you a correct angle once installed tightly , however, in the real world , this won't happen very often, even combining boards and foils of the same manufacturer.
Another reason you might want to change the rake angle is the changing conditions you're sailing in.
So we have two options : just sail the combination as is, and thus, not fully exploit it's potential or, use a combination of variable shims in between the foil mast and tuttle box to po obtain a fixed (and repeatable) rake.
Surely , this is a technical compromise and maybe not perfect but for the moment It might be just "good enough"...
Select to expand quotesegler said..
The 80 degree back tilt of the front rounded taper, and 80 degree front tilt of the back rounded taper are plenty of structure to carry both the up and rocking forces of the foil in the finbox. Don't need any kind of contact along the inside of the top.
The genius of Tuttle's design is that a deep finbox can accept fittings of various heights without compromising strength. Just look at his drawings to see this. His finbox goes up to 5 inches deep, while most fins and foils have heights ranging from 1.5 inches to 3.5 inches.
If you absolutely must fill in the top to get a load carry inside the finbox along the top of the foil, then you are committed to using just one foil for that box.
I use three foils for one finbox. They all have different heights, they all fit in nice and tight to the tapers, and they all work perfectly.
Why limit your options when you don't need to?
The shim I made is removable, if I get another foil will probably have to make a shim specific for it.
Update. Today I used my SB Alloy Race+ in the SB HWR formula board without a fin box spacer. Worked the foil mast head deep into the fin box by rocking back and forth while tightening screws to fully engage the tapers. Went maybe 200 m from shore taking things easy and the front of the foil head pushed up 15-20 mm. Heard a crunch/cracking noise then crashed due to change in mast position. So basically due to the massive forces involved via "foiling" the foil mast head (which is a plastic fitting over the aluminium mast) just deformed and twisted upwards / forward within the fin box. The leading edge of he mast has pushed into the board infront of the fin box and I also think the front of the fin box has split. This brings forward my thoughts of fitting a replacement dedicated foil box.
I guess there are lots of variables relating to type of foil and board, it's intended use, mast with or without a flange, fin box strength and depth, spacer or no spacer, weight of rider and rig, etc etc.
Ian
Select to expand quoteIan85 said..
Update. Today I used my SB Alloy Race+ in the SB HWR formula board without a fin box spacer. Worked the foil mast head deep into the fin box by rocking back and forth while tightening screws to fully engage the tapers. Went maybe 200 m from shore taking things easy and the front of the foil head pushed up 15-20 mm. Heard a crunch/cracking noise then crashed due to change in mast position. So basically due to the massive forces involved via "foiling" the foil mast head (which is a plastic fitting over the aluminium mast) just deformed and twisted upwards / forward within the fin box. The leading edge of he mast has pushed into the board infront of the fin box and I also think the front of the fin box has split. This brings forward my thoughts of fitting a replacement dedicated foil box.
I guess there are lots of variables relating to type of foil and board, it's intended use, mast with or without a flange, fin box strength and depth, spacer or no spacer, weight of rider and rig, etc etc.
Ian
Sorry to hear, is that a foil ready DT box? I only see reviews from 2011 for that board, so pre foiling. But a plastic mast head just sounds wrong, I would contact SB. I thought of putting a foil on my JP Magic ride (power box) with the Chinook powerplate, but was worried I would damage the board, so sold it and got a Goya Bolt with a foil ready DT box (no issues so far after several severe impacts). Learned later that lots of guys with power box boards had lost their foils using the powerplate due to the single M6 power box screw breaking. Kings sells a carbon foil ready DT box called the King Tut for $125.
Select to expand quoteIan85 said..
Update. Today I used my SB Alloy Race+ in the SB HWR formula board without a fin box spacer. Worked the foil mast head deep into the fin box by rocking back and forth while tightening screws to fully engage the tapers. Went maybe 200 m from shore taking things easy and the front of the foil head pushed up 15-20 mm. Heard a crunch/cracking noise then crashed due to change in mast position. So basically due to the massive forces involved via "foiling" the foil mast head (which is a plastic fitting over the aluminium mast) just deformed and twisted upwards / forward within the fin box. The leading edge of he mast has pushed into the board infront of the fin box and I also think the front of the fin box has split. This brings forward my thoughts of fitting a replacement dedicated foil box.
I guess there are lots of variables relating to type of foil and board, it's intended use, mast with or without a flange, fin box strength and depth, spacer or no spacer, weight of rider and rig, etc etc.
Ian
That sucks. Seatex is your next stop. Send Andrea a PM or email. He will give you a code, but it isn't much. I would do research and compare the Seatex V5 vs King Tut for USD 125. You let us know what the difference is. If I am pulling my box apart, I want to do it right.
www.seatexboards.com/product/deep-tuttle-foil-box-fin-v5-foil-ready/
www.kingspaddlesports.com/products/deep-tuttle-box
How to make box.
OK, that makes two instances when the DT finbox on a SB HWR formula board split apart at the front taper.
So, we have to be a bit careful about mounting foils into the DT finboxes on old formula boards that were originally designed for strong side forces of 70 cm fins, but not for the up and rocking forces of foils.
I have thee old Mike's Lab formula boards that seem to have strong DT finboxes for foiling. After three years of foiling on them, I have had zero problems.
Nowadays, the foil-ready boards have strongly reinforced finboxes. At least we all hope so.
Use a leash.
Select to expand quoteSandman1221 said..
So following your advice his board and foil ended up getting damaged.
Huh? Who's advice?
Hi Guys, it's all good.
I am using a race foil with old formula boards and slalom sails until I decide if Foil Racing is for me. I do enjoy the race foil in light wind but as the wind picks up things get a bit scary. 
. Then I much prefer fin/slapper mode.
In reference to the above comments.....
I made a decision based on the fact that the spacer was putting load on the deck of the board /top of fin box causing damage around the front screw hole. Using the foil without a spacer puts load on the fin box tapers, causing it to collapse due to the forward rotation of the foil head within the box. So either way is a potential problem depending on fin box strength. A fin box is made for fins.!!!!
The foil head will be Ok, it is slightly rounded at the front bottom and top rear corners.
I now know that the foil head must be fully seated and supported at the top, as stated by others. A foil box is required for this.
For now will use an older Mistral Devil formula board with a spacer. (Noting that it has some previous slight fin box damage).
Going forward there are options of varying cost..
Repair fin box and fill the void with resin/Q cells mix. See how long this lasts.
Replace the HWR formula board's fin box with a foil box. Others have done this and are still competitive in the races.
Purchase a foil board. Expensive, not many around and tend to get smashed up anyway.
Just enjoy your sailing when you can with whatever gear you have.
Ian
Select to expand quoteZeroVix said..Sandman1221 said..
So following your advice his board and foil ended up getting damaged.
Huh? Who's advice?
Segler's, just read Ian's posts and you see see why I said that.
Select to expand quoteIan85 said..
Replace the HWR formula board's fin box with a foil box. Others have done this and are still competitive in the races.
Just enjoy your sailing when you can with whatever gear you have.
Ian
A vote for just putting in a proper box. Your board has the basic shape. It really only lacks the foil box. That way, your next year's catapults will be on an old nose that won't make you cry each time you bang it. 
Sorry that it didn't work but you have a great attitude. Well done and good luck!
It's simple engineering. Point loads cause failures. Everywhere. Bike frames, fishing rods, windsurfing masts and booms, you name it.
Spread out loads, such as full top to bottom contact of BOTH front and back rounded tapers at their 80 degree rake angles, have a much lower risk of failure. Anything you do to defeat the full contact of both tapers along their ENTIRE lengths will cause problems. Shimming, filling in the top to get a top contact, all that stuff, defeats the full taper contact--along the ENTIRE lengths--of both tapers.
This is not complicated.
Even with full contact, if the finbox fails, it was weak to begin with. It was originally designed for side forces and was not strong enough for the fore and aft rocking forces. Many (or perhaps most) DT finboxes are already strong enough, but we know about these these examples that are not.
I am a retired Boeing scientist. I worked for 30 years with mechanical engineers. I will never shim or fill in a DT finbox. I'd rather avoid failure.
Use a leash.
Select to expand quoteSandman1221 said..ZeroVix said..Sandman1221 said..
So following your advice his board and foil ended up getting damaged.
Huh? Who's advice?
Segler's, just read Ian's posts and you see see why I said that.
Your comment is childish and disrespectful. You need to spend time talking to people that make foil boxes or that have a lot of experience with them over 30+ years. There is nothing wrong with what Segler said. He is correct. A foil approved box is different from a deep tuttle box. The disclaimer from Starboard is for foil boxes, not the SB deep tuttle box from Ian85. There is a reason why I purchased a foil box from Seatex for my Gaastra Vapor 3 board. Does it hold up with my 105kg and 70cm fin? Yes. Was it designed to hold up with my carbon racing foil? No. I understand the limitation and design. I opt not to destroy the board and replace the box. Just a piece of mind. It is only a matter of time until a board that doesn't have a foil box gets damaged. By that, I am not talking about using it to learn, rather when you put a lot of force on it with a larger mast. Most of us are mature enough to know what and who to listen to. But blaming Segler for the board getting damaged? Really?
www.seatexboards.com/deep-tuttle-vs-deep-tuttle-foil-ready-differences/
Select to expand quotesegler said..
I am a retired Boeing scientist. I worked for 30 years with mechanical engineers. I will never shim or fill in a DT finbox. I'd rather avoid failure.
Use a leash.
You're a fellow from Boeing and you're telling us to use a leash?
Yup, sure am. It's called redundancy and excessive safety factor.
The 787 is an all-carbon airplane. Wings, fuselage, empennage, the works. Despite the fact that the airplane is glued together, they still use "chicken fasteners" in certain spots, also for this same redundancy and excessive safety factor.
A leash is cheap insurance.
What has worked for me, with a 20 year old board and no foil flange, is to put the foil head in so it is super, super tight, full contact both sides as far as it possibly can go - and then figure out a shim that will fill in the gap at the front to spread the load and prevent any rotation. And rotation does otherwise occur even when super tight and snug if there is a void above the front and no flange - it might be slight, but even slight implies some point loading.
Because its already at the super tight point, I found it impossible to make a rigid shim that was precisely the right depth. I therefore used a very hard rubber block which deforms very slightly at the super tight point (you can feel it by the increased pressure to screw it into the identical super tight depth).
So, in summary, I think it is not a good idea to make a shim that prevents the tuttle head from going in as far as it needs to go to be super tight both sides, even if that means its sunken in a bit, but once you have got to that point, if there is a void - especially above the front - then its best to fill it so the front bolt cant get pushed up by the very large up force on the front of the tuttle head when foiling. I think thats what Starboard recommend.
The other side of that coin is to reinforce and increase the size of the fin bolt washers - especially the back one which takes a lot of force and cant be too big (mine is 6cm diameter...). Its interesting that Starboard have got that a bit wrong on some of their boards - especially the iqfoil - there isnt room to put a large washer in the oval shaped sunken bolt holes. Fortunately upside down anti twist footstrap plates fit perfectly and are now officially recommended (may even come with the new gear as standard now).
Select to expand quotesegler said..
A leash is cheap insurance.
Nah? I'll just eyeball an inspection for cracks and bends every ~100 hrs, maybe replace a bolt or two .. and hope for the best.
Select to expand quoteZeroVix said..Sandman1221 said..ZeroVix said..Sandman1221 said..
So following your advice his board and foil ended up getting damaged.
Huh? Who's advice?
Segler's, just read Ian's posts and you see see why I said that.
Your comment is childish and disrespectful. You need to spend time talking to people that make foil boxes or that have a lot of experience with them over 30+ years. There is nothing wrong with what Segler said. He is correct. A foil approved box is different from a deep tuttle box. The disclaimer from Starboard is for foil boxes, not the SB deep tuttle box from Ian85. There is a reason why I purchased a foil box from Seatex for my Gaastra Vapor 3 board. Does it hold up with my 105kg and 70cm fin? Yes. Was it designed to hold up with my carbon racing foil? No. I understand the limitation and design. I opt not to destroy the board and replace the box. Just a piece of mind. It is only a matter of time until a board that doesn't have a foil box gets damaged. By that, I am not talking about using it to learn, rather when you put a lot of force on it with a larger mast. Most of us are mature enough to know what and who to listen to. But blaming Segler for the board getting damaged? Really?
www.seatexboards.com/deep-tuttle-vs-deep-tuttle-foil-ready-differences/
Just stated the facts, he followed Seglers advice which convinced him to stop using the shim and next time out the board and foil got damaged, I do not see anything childish or disrespectful about that.
I'm OK with it, too. It's just straight engineering, not my opinion. If you follow the engineering intent of the tuttle design, you will likely have fewer problems or risks than if you defeat it with shims and fill-ins.
About leashes. I know of four expensive foils that broke off at the top of the mast and are now lying on the bottom of the Columbia River. Windance says there are many more. Granted, those were early-generation foils.
