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duzzi said..

utcminusfour said..
At 225 lbs/ 102 kg I always feel like when ever I windsurf or windfoil on free ride gear there is just not enough float especially in light air. I also am not interested in super wide full blown race boards with 10 meter sails. So I designed and built this board to suit my needs for a one board windfoil quiver.

In sub foiling conditions this board it is super fun to cruise around on and even do light air free style as it feels like a long board in a way because of all the float. In marginal foiling weather, it shines with windward ability and early lift. In a breeze, it's short length and good balance make it nimble and easy to steer. I rode a low volume narrow tail board for a couple of years now and it made my feet fatigue and just wore me out. This board is so much more fun and easier in all conditions. Stay tuned for more reports and maybe a video.

Many thanks to David Ezzy for his input on the design.

Water Craft Design Custom Windfoil Board
Length: 6'6"/ 198 cm
Width: 34"/ 86 cm
Thickness: 4" / 10 cm
Volume: 177 liters
Construction: Carbon and Innegra over eps blank
Weight: 21.5 pounds / 9.75 kg
Program: Big Boy Freefoil in 8-30 knots
Sail size: 8^m to 4^m2

The non-pvc construction is interesting! I stopped building my own boards ages ago when composite came into the picture. The extra step, and skill required were just too much. Now might be the time to revisit the idea!

BTW: I have a Flikka custom 217x78 that I feel could use a few extra liters, I am 70 Kg and the board is 117 Liters.

Sandwich construction is indeed much more complicated to build than a single skin laminate. However, there is a reason sandwich construction dominates windsurfing & now foil boards. IMO Impact resistance is way down on the list of needs when trying to build the lightest possible board. The following is a gross generalization since there are so many variations possible: A single skin construction will usually have better impact resistance due to the thicker outer laminate, but single skin boards are prone to buckling & denting. Sandwich construction is better handling the the loads from local stress such as heels, & much much better at handling global forces which could cause a board to crease or buckle. Also, sandwich construction provides a better anchor for fittings - Footstrap plugs, finboxes etc.. which are common failure points. Some of these factors can be improved by clever use of stringers in the case of single skins & local & very specific impact reinforcement in the case of sandwich construction. It certainly could be argued that foil specific boards need very different reinforcement - for example heel dents from pounding over chop or flat jump landings are unlikely to be an issue, however the stress of cantilevering the rig & body weight out in front of the foil is substantial - I have seen boards broken from this or creased. Also riders talk about the flex in the board between foil strut & mast base being significant. One of our local builders makes his Windfoil boards using sandwich AND stringers going forward from the foil box to the front foot. Certainly single skin is a great way for back yard builders to make a usable board, but IMHO it will never have the strength to weight ratio of a good sandwich board...

None of this is meant to diminish UTC's efforts either it looks like a great board!

Select to expand quote

gorgesailor said..

duzzi said..

utcminusfour said..
At 225 lbs/ 102 kg I always feel like when ever I windsurf or windfoil on free ride gear there is just not enough float especially in light air. I also am not interested in super wide full blown race boards with 10 meter sails. So I designed and built this board to suit my needs for a one board windfoil quiver.

In sub foiling conditions this board it is super fun to cruise around on and even do light air free style as it feels like a long board in a way because of all the float. In marginal foiling weather, it shines with windward ability and early lift. In a breeze, it's short length and good balance make it nimble and easy to steer. I rode a low volume narrow tail board for a couple of years now and it made my feet fatigue and just wore me out. This board is so much more fun and easier in all conditions. Stay tuned for more reports and maybe a video.

Many thanks to David Ezzy for his input on the design.

Water Craft Design Custom Windfoil Board
Length: 6'6"/ 198 cm
Width: 34"/ 86 cm
Thickness: 4" / 10 cm
Volume: 177 liters
Construction: Carbon and Innegra over eps blank
Weight: 21.5 pounds / 9.75 kg
Program: Big Boy Freefoil in 8-30 knots
Sail size: 8^m to 4^m2

The non-pvc construction is interesting! I stopped building my own boards ages ago when composite came into the picture. The extra step, and skill required were just too much. Now might be the time to revisit the idea!

BTW: I have a Flikka custom 217x78 that I feel could use a few extra liters, I am 70 Kg and the board is 117 Liters.

Sandwich construction is indeed much more complicated to build than a single skin laminate. However, there is a reason sandwich construction dominates windsurfing & now foil boards. IMO Impact resistance is way down on the list of needs when trying to build the lightest possible board. The following is a gross generalization since there are so many variations possible: A single skin construction will usually have better impact resistance due to the thicker outer laminate, but single skin boards are prone to buckling & denting. Sandwich construction is better handling the the loads from local stress such as heels, & much much better at handling global forces which could cause a board to crease or buckle. Also, sandwich construction provides a better anchor for fittings - Footstrap plugs, finboxes etc.. which are common failure points. Some of these factors can be improved by clever use of stringers in the case of single skins & local & very specific impact reinforcement in the case of sandwich construction. It certainly could be argued that foil specific boards need very different reinforcement - for example heel dents from pounding over chop or flat jump landings are unlikely to be an issue, however the stress of cantilevering the rig & body weight out in front of the foil is substantial - I have seen boards broken from this or creased. Also riders talk about the flex in the board between foil strut & mast base being significant. One of our local builders makes his Windfoil boards using sandwich AND stringers going forward from the foil box to the front foot. Certainly single skin is a great way for back yard builders to make a usable board, but IMHO it will never have the strength to weight ratio of a good sandwich board...

None of this is meant to diminish UTC's efforts either it looks like a great board!

Can't beat sandwich for stiffness, but I wonder if one can limit or eliminate its use for a foil board (well UTC has obviously already done that!). Maybe just have a "stringer"connecting mast and foil boxes, and the rest of the board "suspended" from the stringer. That way longitudinal stiffness should be plenty, but construction much simplified ... now I am tempted to go play with Shape 3D ...

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boardsurfr said..
The construction raises a few interesting questions:
- do short foilboards not need a sandwich construction because hitting chop is no issue?
- does the Innegra layer provide better impact protection in catapults?
- does it make sense to put a brittle (carbon) layer on top of the Innegra?

Only time will tell. It will be interesting to hear how the board holds up over time, say 150 or 200 sessions.

A couple of questions:
- are you not using any EVA foot pads, or are they just hard to see?
- is the Innegra you are using just the polypropylene (Innegra S), or is it mixed with other fibers (Innegra H)? If it's mixed - with what?

Okay ya'll, I am about three months in and roughly 30 sessions on this board. I am finding the skin is starting to delaminate from the blank under the foot straps and where the board rides on the roof racks.

I would not recommend this construction for long term durability.

That said I have a 120l board built in a similar manner and it is still going strong after 3 years of learning and hard use. I think the foam in the 120l is 1.5#/ft^3 versus 1#/ft^3 in my newer board. There is also a lot deck shape on my old board near the straps where on the new shape it is perfectly flat so not as stiff from geometry. On the new board I stacked 5 or more layers of Innegra on the nose and I have had some big catapults without damage. Given that and how well my old board has held up I know there is some potential for this construction but it is not for everyone.

I am still really digging the shape and I want to figure out a way to keep this investment going. I am absolutely in love with the windward ability created by the wide tail. I am really a fan of hollow construction and really would like to see the thirsty EVA blank go away entirely. My craziest idea so far is to cut the bottom skin of the board off at the sharp rail and use acetone to dissolve the blank. Then vacuum core and another skin to both parts on the inside than laminate the two parts back together. Or, use the board as a plug to make female molds. Or just add core and carbon to the top of the deck where the dents are. Or cut my losses and just fill the delam with gorilla glue to keep it going a bit more then donate the blank to my buddy who builds smaller surf boards. Any suggestions?

Select to expand quote

utcminusfour said..

boardsurfr said..
The construction raises a few interesting questions:
- do short foilboards not need a sandwich construction because hitting chop is no issue?
- does the Innegra layer provide better impact protection in catapults?
- does it make sense to put a brittle (carbon) layer on top of the Innegra?

Only time will tell. It will be interesting to hear how the board holds up over time, say 150 or 200 sessions.

A couple of questions:
- are you not using any EVA foot pads, or are they just hard to see?
- is the Innegra you are using just the polypropylene (Innegra S), or is it mixed with other fibers (Innegra H)? If it's mixed - with what?

Okay ya'll, I am about three months in and roughly 30 sessions on this board. I am finding the skin is starting to delaminate from the blank under the foot straps and where the board rides on the roof racks.

I would not recommend this construction for long term durability.

That said I have a 120l board built in a similar manner and it is still going strong after 3 years of learning and hard use. I think the foam in the 120l is 1.5#/ft^3 versus 1#/ft^3 in my newer board. There is also a lot deck shape on my old board near the straps where on the new shape it is perfectly flat so not as stiff from geometry. On the new board I stacked 5 or more layers of Innegra on the nose and I have had some big catapults without damage. Given that and how well my old board has held up I know there is some potential for this construction but it is not for everyone.

I am still really digging the shape and I want to figure out a way to keep this investment going. I am absolutely in love with the windward ability created by the wide tail. I am really a fan of hollow construction and really would like to see the thirsty EVA blank go away entirely. My craziest idea so far is to cut the bottom skin of the board off at the sharp rail and use acetone to dissolve the blank. Then vacuum core and another skin to both parts on the inside than laminate the two parts back together. Or, use the board as a plug to make female molds. Or just add core and carbon to the top of the deck where the dents are. Or cut my losses and just fill the delam with gorilla glue to keep it going a bit more then donate the blank to my buddy who builds smaller surf boards. Any suggestions?

I would probably vote for gorilla glue and spend the additional energy on designing/building you next board.

Select to expand quote

utcminusfour said..

boardsurfr said..
The construction raises a few interesting questions:
- do short foilboards not need a sandwich construction because hitting chop is no issue?
- does the Innegra layer provide better impact protection in catapults?
- does it make sense to put a brittle (carbon) layer on top of the Innegra?

Only time will tell. It will be interesting to hear how the board holds up over time, say 150 or 200 sessions.

A couple of questions:
- are you not using any EVA foot pads, or are they just hard to see?
- is the Innegra you are using just the polypropylene (Innegra S), or is it mixed with other fibers (Innegra H)? If it's mixed - with what?

Okay ya'll, I am about three months in and roughly 30 sessions on this board. I am finding the skin is starting to delaminate from the blank under the foot straps and where the board rides on the roof racks.

I would not recommend this construction for long term durability.

That said I have a 120l board built in a similar manner and it is still going strong after 3 years of learning and hard use. I think the foam in the 120l is 1.5#/ft^3 versus 1#/ft^3 in my newer board. ...

Bit disappointing but good to know ... I am 70Kg so the innegra route might still be viable. Just found a CNC milling operator in South Cal that does all the carving + boxes. Or ... semi-hollow construction like this one? st

Select to expand quote

duzzi said..

utcminusfour said..

boardsurfr said..
The construction raises a few interesting questions:
- do short foilboards not need a sandwich construction because hitting chop is no issue?
- does the Innegra layer provide better impact protection in catapults?
- does it make sense to put a brittle (carbon) layer on top of the Innegra?

Only time will tell. It will be interesting to hear how the board holds up over time, say 150 or 200 sessions.

A couple of questions:
- are you not using any EVA foot pads, or are they just hard to see?
- is the Innegra you are using just the polypropylene (Innegra S), or is it mixed with other fibers (Innegra H)? If it's mixed - with what?

Okay ya'll, I am about three months in and roughly 30 sessions on this board. I am finding the skin is starting to delaminate from the blank under the foot straps and where the board rides on the roof racks.

I would not recommend this construction for long term durability.

That said I have a 120l board built in a similar manner and it is still going strong after 3 years of learning and hard use. I think the foam in the 120l is 1.5#/ft^3 versus 1#/ft^3 in my newer board. ...

Bit disappointing but good to know ... I am 70Kg so the innegra route might still be viable. Just found a CNC milling operator in South Cal that does all the carving + boxes. Or ... semi-hollow construction like this one?

st

Bruce creations rocks!

Select to expand quote

utcminusfour said..

boardsurfr said..
The construction raises a few interesting questions:
- do short foilboards not need a sandwich construction because hitting chop is no issue?
- does the Innegra layer provide better impact protection in catapults?
- does it make sense to put a brittle (carbon) layer on top of the Innegra?

Only time will tell. It will be interesting to hear how the board holds up over time, say 150 or 200 sessions.

A couple of questions:
- are you not using any EVA foot pads, or are they just hard to see?
- is the Innegra you are using just the polypropylene (Innegra S), or is it mixed with other fibers (Innegra H)? If it's mixed - with what?

Okay ya'll, I am about three months in and roughly 30 sessions on this board. I am finding the skin is starting to delaminate from the blank under the foot straps and where the board rides on the roof racks.

I would not recommend this construction for long term durability.

That said I have a 120l board built in a similar manner and it is still going strong after 3 years of learning and hard use. I think the foam in the 120l is 1.5#/ft^3 versus 1#/ft^3 in my newer board. There is also a lot deck shape on my old board near the straps where on the new shape it is perfectly flat so not as stiff from geometry. On the new board I stacked 5 or more layers of Innegra on the nose and I have had some big catapults without damage. Given that and how well my old board has held up I know there is some potential for this construction but it is not for everyone.

I am still really digging the shape and I want to figure out a way to keep this investment going. I am absolutely in love with the windward ability created by the wide tail. I am really a fan of hollow construction and really would like to see the thirsty EVA blank go away entirely. My craziest idea so far is to cut the bottom skin of the board off at the sharp rail and use acetone to dissolve the blank. Then vacuum core and another skin to both parts on the inside than laminate the two parts back together. Or, use the board as a plug to make female molds. Or just add core and carbon to the top of the deck where the dents are. Or cut my losses and just fill the delam with gorilla glue to keep it going a bit more then donate the blank to my buddy who builds smaller surf boards. Any suggestions?

Nice! Got a good run out of it anyway... I mean the failure mode is fairly predictable for single skins. The thickness of your board & square rails probably prevented more global failure due to flex or buckling. I would second the local area fix with gorilla glue etc, then just keep riding it while you focus on your next creation...

Hi utcminusfour,

I'm very interested in this design, and how the David Ezzy sort of "unique" design choice of a short but quite large board flies for amateur Windfoilers.

Especially if there is a significant penalty in light wind due to this so large bottom, or if this is an acceptable trade-off with simplicity. I've heard he says he uses a similar board from 5 to 40 knts. 5 knts is on the low side.

Do you pop the board out of the water before planing, or do you need it semi planing beefore take-off ?

Is the bottom flat (on your board and David Ezzy one) ?

I'm curious as it looks like a back to basics approach without any aesthetic considerations:
- large where it is needed when flying,
- used strapless if less power needed,
- Not designed to go fast at water surface, but to support foil / rig / sailor
- optimized for fast planing ?

JMF

That hollow kite board is awesume.

Dam, I just sold my 520 and 500cm carbon masts....could of cut them up and created a semi hollow board.

jmf1,
First off thanks for your interest!

Secondly, a bit of a disclaimer is necessary. I designed (with some legendary input) and built this board so I am biased! Also, I ride at an intermediate level so my comments are appropriate for beginners up to intermediate level. There are others on this forum that are more relevant in regards to advanced technique like jumping, carving hard, surf riding, racing and so on.

To answer your specific questions, yes the board is flat side to side on the bottom and the back end of the rocker line is straight. With my Moses 1100 the board launches before planning if foil pumped, with my 790 wing it is at or closer to planning speed but foil pumping helps lower the take off speed.

This is a good time for a review as I have had a lot of time on the water with this board. Forgive my lengthy reply, this topic gets me fired up.

My goals was to create a set up that is simple to build, safe, ease to use, dependable, useful in a broad range of conditions and most of all FUN! In a nut shell I think this design goes a long way to achieving the goals stated above. I have at least 95 sessions on this board now. It is still intact and the one I choose to ride in every condition over my other options.

Pros:
It floats me! I think newbie's are too quick to ride low volume hulls or they are forced to ride what the industry has produced. I rode this winter with a REALLY skilled short board rider and we got caught a long way from the launch in a dying breeze. I had a nice cruz back to the launch site; I had to go pick him up way down wind. It had nothing to do with my foil it was my hull volume.

It is REALLY stable in displacement mode. This gives you a chance to foil more because you are not falling in and up-hauling is easy.

It carries sail well. I never would have dreamed of using a 7.5m sail in 25 knot gusts but the width makes it work. It goes upwind in light air with big sails. Width at the foot straps is the key here.

Big range, it will long board ya home when the wind dies because of the volume and maintains control in big breeze because it is compact. It is not perfect at the extreme ends of the scale but it will get you out there. It is time on the water that produces real performance.

It is not like anybody else's board except Dave Ezzy's.

Flat decks are more comfortable for foiling. Flat decks coupled with boxy rails push the volume up so you can design a more compact shape.

Cons:
Volume = weight. I am working on getting the weight out of the board with hollow home brew construction, stand by. A lot of folks say weight only matters carrying it to the water. FOOKIN HELL, carrying heavy gear to the water, through the surf, over the seawall, through the pluff mud really FOOKIN SUCKS! Weight matters! Heavy gear is not fun! The foils can be built way lighter; I just held a modern surf/kite foil in my hands and windsurfing foils are way behind. That's another thread.

People will think your custom board is an old formula board, even though it is over a foot shorter. I usually don't care what other people think but this one did sting a little.

It is Sticky in light air. While the float and tail width is comfortable in light air it is not fast and therefore hurts early take off. I have added a Moses 1100 wing to the quiver and it is mitigating this a lot because it helps to foil pump the hull free. Before this big wing I found myself reaching for the 7.5m sail if there were single digit lulls around even if the puffs were in the teens.

It snags with touch downs. It is a bigger target so it hits more often than smaller narrower hulls. I want to explore beveled rails with my next design and make up my own mind on the merits of flat and boxy verses bevels. I have not put enough energy into foil rake, I know this is a way to improve this a bit, but still it's a bigger target.

It is harder to carry. Bigger is harder to carry. This is the biggest con for me.

Some might say that it is too wide for sails 4m and below. I have felt that imbalance; I just moved my back foot inboard to correct it. You can also move the straps inboard or riding strapless would also solve this. If your venue is not that windy this shape is a good compromise.

Construction:
The single skin construction raised a few doubts and even I pointed out some minor delam a few months ago. I did not do anything about it and it is still trucking. In hind sight, if I wanted a simple build method I would still use the 1# foam and add some thin wood veneers to the deck and bottom. The innegra patches at the nose worked great. I have catapulted hard so many times and the nose is still intact.

Conclusion:
Overall the concept has fit my needs well and I can recommend the type to others with similar goals. It is really appropriate for those still learning skills or those that appreciate designs that make sailing easy. My stoke is still high enough for this concept that when I get my next design on the water I plan on making molds from this board to try and get the weight out. Anyone interested in the 3D CAD file is welcome to email me; I would even do some quick scaling to accommodate your weight. Thanks for reading!

Did you keep a tally on build cost?

Also I've been thinking about ways for home builders to produce hollow boards and I think I've got a handle on what might work. Especially for foil boards which don't need a lot of top or bottom shaping.

Around $1500. Not all the cost is in that one board, I am still using tools and some materials. It is for the process not the product.
Here is one method that makes sense
www.alaljojo.com/

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utcminusfour said..
Around $1500. Not all the cost is in that one board, I am still using tools and some materials. It is for the process not the product.
Here is one method that makes sense
www.alaljojo.com/

That method is more or less exactly what I had in mind!
Except I was thinking I'd run a central spine as far forward as the mast track and also run some "ribs" out to the footstrap positions.

Maybe I need to just get off my butt and build it. Or perhaps just do a mock up in the cheapest foam sheets I can find to start with.

Awesome post. 95 sessions! Love it.

I learned the hard way of choosing too little volume. I am #245 currently, and initially went with the Wizard 125 based on advice from some very good riders. Great when powered, but those times the wind went below 10mph meant sinking the board and risking foil dings, and tricky uphauls to crawl back to the beach. Not worth it. Christmas, I went with the SB Foil-X 145, and so far, fantastic. Same agility, but the proper volume I needed. I will go out anywhere, anytime, and I am confident I can easily get back. Now, I dream of 95 sessions!

I agree about carrying around a big heavy foil. I hope materials/design technology can advance us there soon.

Select to expand quote

utcminusfour said..
Around $1500. Not all the cost is in that one board, I am still using tools and some materials. It is for the process not the product.
Here is one method that makes sense
www.alaljojo.com/

Is that a wooden skin build? Like www.grainsurfboards.com/ ? I've had plans for a mini malibu for years but never got around to it. I'd be interested in knowing if a wood strip windsurf board would hold up to the stresses of the sport. I've built a couple of wooden boats and may be interested in making a foil board.

Select to expand quote

shmish said..

utcminusfour said..
Around $1500. Not all the cost is in that one board, I am still using tools and some materials. It is for the process not the product.
Here is one method that makes sense
www.alaljojo.com/

Is that a wooden skin build? Like www.grainsurfboards.com/ ? I've had plans for a mini malibu for years but never got around to it. I'd be interested in knowing if a wood strip windsurf board would hold up to the stresses of the sport. I've built a couple of wooden boats and may be interested in making a foil board.

No, the alaljojo is compsite cored panels top and bottom with CNC milled foam rails that the end user glasses together. The concept is not much different than the wood surf board methods. The composite panels are stiffer than wood so less stiffners are needed. The have a mold for the top and bottom panels, the magic is that it ships flat so shipping is reasonable and with everything cnc cut and molded at the factory it is pretty easy to build. If I wanted a 87 liter freestyle board I would be all over this.

Select to expand quote

Grantmac said..

utcminusfour said..
Around $1500. Not all the cost is in that one board, I am still using tools and some materials. It is for the process not the product.
Here is one method that makes sense
www.alaljojo.com/

That method is more or less exactly what I had in mind!
Except I was thinking I'd run a central spine as far forward as the mast track and also run some "ribs" out to the footstrap positions.

Maybe I need to just get off my butt and build it. Or perhaps just do a mock up in the cheapest foam sheets I can find to start with.

I have yet to find "cheap" foam panels with the required density and sheer strength. PVC foam is expensive and shipping is brutal. If you know a composite boat builder you might be able to piggy back with their orders. I am trying cross cutt Divinycell for my next attempt because it is the cheapest I could find, it ships rolled. The cuts can fill with glue but if you put the binding scrim on the outside of the bend direction the gaps close up. I just might make it work without to much weight. Cross cut balsa can be affordable but the material is heavier than foam. The 6mm foam currently being used in boards is to thin for a hollow board, I am using 3/8" and 1/2" for my next move.

I was thinking XPS rigid insulation just to see how it would fit together. Probably 1" because it comes in 4x8' sheets for $30 here. The expensive parts would be the cloth and resin.

On the other hand I do live near a bunch of boat builders so maybe I could see about their off cuts etc.

1/2" PVC should be plenty. Especially if you did the deck and internal structure first then glassed some reinforcements on the inside before adding the bottom.

Back in the '80 when XPS panels became popular for building construction, I remember reading an interview with a successful surfboard shaper in California. He thought that the XPS would revolutionize surfboard building. He shaped a bunch of boards with it. Turns out they all delaminated. Apparently difficult to adhere.

Why did you add a track mount with your weight? Why didn't you put a reinforced foil deep tuttle box in? Like the ones from Seatexboards? Lot of leverage if you are adding a longer mast and your weight. Just curious. Thanks.

ZeroVix,

The short answer is that I wanted to have the freedom to experiment with the foil location and to be able to try foils built with flange mounts.

I actually have both; I started with a deep Tuttle from Gofoil and added Chinook boxes to it with vacuum bagged carbon. Then I installed this "box" as normal with extra carbon patches to the deck and bottom. At this point I am confident that it is bomb proof because I have hit one of everything at speed

I almost always use the track mount because it allows me to easily adjust the balance with different sails and foils. With bigger wings, bigger sails and lighter wind I move the foil 2" or more forward of where the Tuttle box is. This way I keep the same front/back foot pressure balance across the range. Increasing the angle of the stab creates drag and switching out the fuse is more time consuming and if it is not a switch fuse it's more gear. I use the Tuttle in shallow water. I sometimes use the Tuttle in the surf if the shore brake is challenging because it is lighter without the track adapter and it is shallower making getting in and out easier.

Flanged foils mast and track boards can be built lighter than Tuttle set ups because the wider attachment point lowers the reaction loads and stresses in both the mast and board. Sadly these refinements are not common on windfoiling gear.

I prefer flanges with the bolts holes that are open on the ends. You can leave the nuts and bolts in the board all the time; just tighten them up after you take the foil away. When you set up just loosen, slide them in and retighten. This is as quick as installing a 2 bolt Tuttle.

I hope manufactures will produce some windfoiling masts with a flange and open bolt slots beacuse I want to ditch the 1.5# adaptor!!!! I probally will build a board with only tracks at some point to save weight.

Select to expand quote

marc5 said..
Back in the '80 when XPS panels became popular for building construction, I remember reading an interview with a successful surfboard shaper in California. He thought that the XPS would revolutionize surfboard building. He shaped a bunch of boards with it. Turns out they all delaminated. Apparently difficult to adhere.

Foam insulation board is not strong enough for sanwich construction. It is worse than the average eps blank.

Here is the best way I have seen to install tracks. This is from Dwight Fisher's site www.supsurfmachines.com/ who is IMO is leading the way in the wingfoil boards. If it's a tuttle or tracks you need to connect the loads to the deck skin. Adding a big chunk of high density foam that doesn't reach the deck is heavy and WEAK!

Select to expand quote

utcminusfour said..
jmf1,
First off thanks for your interest!

...

Cons:
Volume = weight. I am working on getting the weight out of the board with hollow home brew construction, stand by. A lot of folks say weight only matters carrying it to the water. FOOKIN HELL, carrying heavy gear to the water, through the surf, over the seawall, through the pluff mud really FOOKIN SUCKS! Weight matters! Heavy gear is not fun! The foils can be built way lighter; I just held a modern surf/kite foil in my hands and windsurfing foils are way behind. That's another thread.

...

It is Sticky in light air. While the float and tail width is comfortable in light air it is not fast and therefore hurts early take off. I have added a Moses 1100 wing to the quiver and it is mitigating this a lot because it helps to foil pump the hull free. Before this big wing I found myself reaching for the 7.5m sail if there were single digit lulls around even if the puffs were in the teens.

....
Conclusion:
Overall the concept has fit my needs well and I can recommend the type to others with similar goals. It is really appropriate for those still learning skills or those that appreciate designs that make sailing easy. My stoke is still high enough for this concept that when I get my next design on the water I plan on making molds from this board to try and get the weight out. Anyone interested in the 3D CAD file is welcome to email me; I would even do some quick scaling to accommodate your weight. Thanks for reading!

Thanks utcminusfour for all the provided information !

With a board below 10kg, not easy to build for much less. At least it is aligned with many commercial products, when you go to cost effective construction techniques, lake Cobra midrange boards.

For the sticky in light air, I wonder if there are ways to significantly improve that aspect if we want to stick max width around 85 cm:
- a bit of a narrower tail ?
- steps/cut-outs like SB IQFoils ? But I can't convince myself that this is really effective considering the low speeds at which foil kicks in, and the pumping down on the back of the board.

JMF

Thanks for all the information. I am going to speculate that you got more weight than you think with the mast track & tuttle box. I understand the convenience of having the track, but I would be curious what the weight is. What is the largest sail and foil mast that you are using?

I weighed everything at every step of construction and kept good notes. That box with with tracks weighed 1.55 lbs as it got installed into the blank. My biggest sail is a 7.5m and my mast is 85cm plus 10cm because of the adapter.

People over on Swaylocks have mostly figured out how to build with XPS. Its actually stronger than EPS in a single skin format.

There's nothing wrong with single skin builds.If they last 2 seasons then my goal has been reached as I'll have a new build ready to go. They are fast to build and are cheap.



This is a 4,9"x 29
2 layer 6 oz S glass + patches +Vector carbon netting.
clear epoxy
2.0 eps foam 1/8 wood stringer
Deep tuttle
Simple like a surfboard

Gwarn,
Effn sweet mate!

Select to expand quote

Gwarn said..
There's nothing wrong with single skin builds.If they last 2 seasons then my goal has been reached as I'll have a new build ready to go. They are fast to build and are cheap.

You use those half straps much? On my lightwind board I am front strap only currently. I think I move my back foot around too much in lightwind to commit to any particular strap position, also I don't want the strap getting in the way. But those half straps do take up less space

On my medium to highwind board i am full back center strap