For if anyone is interested, here the shape of the "new" Serum explained. The bottom shape is a continuing V from front to back combined with a deep double concave which gradually starts from 30cm from the nose, is strongest below the front straps and gradually reduces again to be zero 50mm behind the tail. The V in the front breaks the chop and gives more rocker on the front rail for better turning. The deep double concave channels the water. The deepest point of the concaves is not in the centre but are placed a little closer to the rail which gives more grip in the turn. The deep double concaves do "eat" about 1L of volume, however, since the sizes stay the same, it still feels like a board with 1L more.
As with all Witchcrafts, the volume is placed between the centre and rails to not to have too thick rails nor a too thick middle to prevent it feels like a tree trunk. The centre of bouyancy is located right behind the mastbox. You only need volume when not planing and when you are not planing, the fins don?t work so you need to step forward anyway to not turn into the wind. Also typical for Witchcraft: the rails are very round in the front to guide the water under the board, going sharp towards the back to give more planing area, a clean water release, more reactivity and more grip. And toe-in with pre twisted side fins off course. As you can see, the inserts and rails are also shaped by CNC. The bottom PVC is tapered towards the nose.

how deep is the concave in your picture.

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SchobiHH said..
how deep is the concave in your picture.

8mm. Here a screen shot from my shaping program.

so concave runs out the tail ... just ...?

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Mark _australia said..
so concave runs out the tail ... just ...?

Yes, off course it needs to reduce towards the tail, if not you get a negative rocker on the rails. I don?t use tail kick either. The rocker very gradually goes straighter towards the back. When you turn, you use more lenght than when planing and its the total amount of rocker of the length that is in the water that counts.

I know it reduces I think you misunderstood me. Runs out the tail ie: through the tail and keeps going, to a zero point that is off the board. So I meant does the concave go all the way to tail. Still concave at the very end. As you said it ends 50mm behind tail. So there is some concave at the very back. yes?
Not many folks do this, but one board I know of with it is amazing, so I am keen to hear your rationale (as opposed to normal flat vee at tail)

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Mark _australia said..
I know it reduces I think you misunderstood me. Runs out the tail ie: through the tail and keeps going, to a zero point that is off the board. So I meant does the concave go all the way to tail. Still concave at the very end. As you said it ends 50mm behind tail. So there is some concave at the very back. yes?
Not many folks do this, but one board I know of with it is amazing, so I am keen to hear your rationale (as opposed to normal flat vee at tail)

Yes, there still is some double concave combined with V right at the tail. Below is the section at 105 from the tail.The V ends 400mm behind the tail. I like to have grip on the rail. A straight V has less grip and also less planing as it creates more rocker on the rail and the water is pushed out. For the grip also the rails in the back half are quite a bit sharper than most (all?) brands but rounder than most (all?) brands in the front to guide the water under the board. The sharper rails also make the board more reactive and gives more drive plus it make the planing area wider without having to make the board wider and it gives a cleaner release. The only downside is that in very choppy waves, it can become too direct. Until I visited WA (20 years ago) I never understood why most WA developed boards are shaped like they are, with a straighter outline, rounder rails and tail kick. Performance and range wise pretty bad. But, due to the continental shelf, many of the waves are pretty to very choppy and hard to read (even 50 knots Pozo or the North Sea is clean compared to some waves there, the only clean wave I sailed there was Yardie Creek, that was great), you get huge swells due to having an enormous amount of ocean to the west and south but bigger swells are filtered out by the shelf and a wave can break 5+ times on their way to the coast, there is hardly any rip nor crowds and plenty of wind so going upwind or early planing is not important. Here on the north shore of Fuerteventura we have loads of good waves for pretty much any direction and on average lighter winds. Most waves are also pretty user friendly so it can get crowded and getting upwind well and plane early make a big difference in the amount of waves you can get. These same treats are very usefull in most spots but, AFAIK, WA and Hookipa.

how do you know that your V runs out 400 after the tail?

BTW, I am a big fan to run the concave through the full board. To me it does not make sense to have a flat V in the back. the board is much more predictable. But with the standard shape program almost everybody uses, it is near impossible to design the proper rail-side curve to allow this.

Tasmania is nice if you dont want to put up with those choppy WA waves

Just don't take those poorly performing wa boards with limited range to tassie. Lol..

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SchobiHH said..
BTW, I am a big fan to run the concave through the full board. To me it does not make sense to have a flat V in the back. the board is much more predictable. But with the standard shape program almost everybody uses, it is near impossible to design the proper rail-side curve to allow this.

My program Virtual Shaper was specially designed for me. There are 3 modes: Shape, construction and CNC. With the shape module I design the outside shape.With the construction I can define the PVC thickneses (to take off for the EPS blank), the taper of the PVC thickness, any reinforcement blocks and the size of the inserts. Which is then all cut by CNC.
In the CNC mode I design the blank, place the shape inside and define the milling paths for the different tools and the positions of the vacuum suckers.

I can define the flow of the V and concave with 8 values:

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Gestalt said..
Just don't take those poorly performing wa boards with limited range to tassie. Lol..

That was 20 years ago. They are not as bad anymore but you still see these traits with a more paralel outline, rounder rails and tailkick in some boards. Not good for less than ideal conditions like you get in the North Sea or other beach breaks with cross on shore condtions and a strong rip down wind directly along the beach. You can stand in knee deep water, 20m from shore and your legs are being pulled from under you. So as soon as you jump on the board, the apparent wind drops and you drift down wind very quickly. You need a fast planing board with good up wind ability to get through this. Once you are through the first 50m, or over the first sand bar, this rip disappears. Then there are also spots with big tides and strong tidal rips, often combined with the beach rip. In the North Sea, where I come from, the tides are around 3m, every 6 hours. In the british channel the tide can be 12m..... In WA the tide is like 50cm max once a day?But there are a whole lot more windsurfers around the North Sea. At spots like Wijk aan Zee in Holland you can see 300 sailors out on a good day. Within a 1 hour drive there are like 10 million people living but people also come from Germany on a good forecast. And there are more spots like that.

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Bouke-Witchcraft said..

My program Virtual Shaper was specially designed for me. There are 3 modes: Shape, construction and CNC. With the shape module I design the outside shape.With the construction I can define the PVC thickneses (to take off for the EPS blank), the taper of the PVC thickness, any reinforcement blocks and the size of the inserts. Which is then all cut by CNC.
In the CNC mode I design the blank, place the shape inside and define the milling paths for the different tools and the positions of the vacuum suckers.

I can define the flow of the V and concave with 8 values:

That is indeed quite impressive. I think that "parametric" CAD is the best way to do surfboard shaping, but is not explored much. You also do the concaves the same way? From would I read in your post, I thought their profile can be asymmetrical?

Yes there are 2 ways to design the concaves. A straight circular concave or double concave but I can also combine a single concave with plain V and then the deepest part of the double concave is at around 40% from the rails. I have this program since 20 years. It was made by a student in ships engineering who was also a hobby shaper and he designed this originally for himself. He gave it to me to try and I found it worked a lot better than other programs. It works with longitudinal curves which have a 2 step smoothening. Lateron it was adapted to my way of working, the parameters I use etc. For the rockerline I have 6 different options. For wave boards I pretty much always use the Witchcraft option, which is always 100% smooth. Lateron we added other types for surfboards or slalom boards. Various people have said he is a mathematical genious. He now has a very high position with a research institute.Note that the indicated tailrocker is 3mm lower since the deck sandwich always pulls the tail up a bit.

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Bouke-Witchcraft said..

Gestalt said..
Just don't take those poorly performing wa boards with limited range to tassie. Lol..

That was 20 years ago. They are not as bad anymore but you still see these traits with a more paralel outline, rounder rails and tailkick in some boards. Not good for less than ideal conditions like you get in the North Sea or other beach breaks with cross on shore condtions and a strong rip down wind directly along the beach. You can stand in knee deep water, 20m from shore and your legs are being pulled from under you. So as soon as you jump on the board, the apparent wind drops and you drift down wind very quickly. You need a fast planing board with good up wind ability to get through this. Once you are through the first 50m, or over the first sand bar, this rip disappears. Then there are also spots with big tides and strong tidal rips, often combined with the beach rip. In the North Sea, where I come from, the tides are around 3m, every 6 hours. In the british channel the tide can be 12m..... In WA the tide is like 50cm max once a day?But there are a whole lot more windsurfers around the North Sea. At spots like Wijk aan Zee in Holland you can see 300 sailors out on a good day. Within a 1 hour drive there are like 10 million people living but people also come from Germany on a good forecast. And there are more spots like that.

I have a board from 20 years ago, it was designed and built in wa by one of their legend shapers. It doesn't display any of the traits you describe. Outline is not parallel, rails are hard and the double concave through the tail extend beyond the outline. It was also not designed in cad. So what are you on about.
I have boards with and without tail kick. some slalom boards have tail kick as do some speed boards. Tail kick is not a problem fwiw.
some jp fsw boards use flat centre rocker with more rail rocker. seems to work for them.

I have another board here same deal different shaper. not quite as old though.

anyways, here is my final thought.

It would be great if you stopped talking in absolutes, there are no absolutes in design, there is merely a series of choices that lead to an outcome. That outcome being defined by the choices.

your posts continue to push the idea that you have somehow figured out some magic combination that elevates you above everyone.
this is of course simply not true. I'm not suggesting your boards aren't great boards but I'm constantly struck by the thought of how much better your boards could be with a different approach. The problem with absolutes is it prevents exploring all the options both good and bad.

it seems to me other board designers don't suffer from this. Don't feel the need to slag off others and are secure enough in themselves to be able to celebrate others

So less snake oil more....

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Gestalt said..

Bouke-Witchcraft said..

Gestalt said..
Just don't take those poorly performing wa boards with limited range to tassie. Lol..

That was 20 years ago. They are not as bad anymore but you still see these traits with a more paralel outline, rounder rails and tailkick in some boards. Not good for less than ideal conditions like you get in the North Sea or other beach breaks with cross on shore condtions and a strong rip down wind directly along the beach. You can stand in knee deep water, 20m from shore and your legs are being pulled from under you. So as soon as you jump on the board, the apparent wind drops and you drift down wind very quickly. You need a fast planing board with good up wind ability to get through this. Once you are through the first 50m, or over the first sand bar, this rip disappears. Then there are also spots with big tides and strong tidal rips, often combined with the beach rip. In the North Sea, where I come from, the tides are around 3m, every 6 hours. In the british channel the tide can be 12m..... In WA the tide is like 50cm max once a day?But there are a whole lot more windsurfers around the North Sea. At spots like Wijk aan Zee in Holland you can see 300 sailors out on a good day. Within a 1 hour drive there are like 10 million people living but people also come from Germany on a good forecast. And there are more spots like that.

I have a board from 20 years ago, it was designed and built in wa by one of their legend shapers. It doesn't display any of the traits you describe. Outline is not parallel, rails are hard and the double concave through the tail extend beyond the outline. It was also not designed in cad. So what are you on about.
I have boards with and without tail kick. some slalom boards have tail kick as do some speed boards. Tail kick is not a problem fwiw.
some jp fsw boards use flat centre rocker with more rail rocker. seems to work for them.

I have another board here same deal different shaper. not quite as old though.

anyways, here is my final thought.

It would be great if you stopped talking in absolutes, there are no absolutes in design, there is merely a series of choices that lead to an outcome. That outcome being defined by the choices.

your posts continue to push the idea that you have somehow figured out some magic combination that elevates you above everyone.
this is of course simply not true. I'm not suggesting your boards aren't great boards but I'm constantly struck by the thought of how much better your boards could be with a different approach. The problem with absolutes is it prevents exploring all the options both good and bad.

it seems to me other board designers don't suffer from this. Don't feel the need to slag off others and are secure enough in themselves to be able to celebrate others

So less snake oil more....

Its not slagging off, it is an observation. Its quite simple, a board with tail kick is like sailing with the hand brake on. It reduces the windrange quite a lot. So does a paralel(ish) outline. And these traits are fairly often seen on boards developed in WA. Like the old Evo?s but also some of the more current shapes. It even says in the description of the current Severne Nano with 3 times the word paralel. And it has tail kick. When you know the conditions there, it makes sense as it smoothes out chop on a wave. With my boards, I was not really comfortable in many of the spots within the continental shelf. Hitting chop it was sometimes reacting too quick. Maybe I had a particularly bad period, I dont know. At Gnaraloo and Ningaloo they were working fine. I saw Glenn Alexander sailing Green Head, which was terribly choppy. As it is an off shore reef, the 1m wind swell ran at a 90 degree angle through the 2m swell. The wave was wobbling all over the place. But he was totally dialled into it like there was no chop at all and ripping out there on his own. But off course getting planing early or getting up wind well has no priority in such conditions.Especially nowadays there are other shapes from WA but from other locations you do not see those traits at all, that is my observation. It is my job to know the conditions and the boards customers refer to. I also get to check out many boards here when we get them to repair from visitors.