what is the best way for an accurate rocker line measurement (tail kick Rocker at 100 120 150 200 cm from the tail) in a wave board . Some experts opinion is with a straight profile (ruler) of about 2m long, aluminium is the best and not taking measurements when putting a board in flat floor ?Rocker could differ when measured at the center line and when measured at the rails (side view)
thanks

Best way is YOUR style of measurement done the same way on every board.

The underlying problem with measuring rocker on modern boards is that shapes vary so much.
If they were all the same length, then it would be easier.
Slalom boards are easier in that they have all gravitated towards a similar/standardised length, but wave boards haven't.

Modern wave boards now vary from 240cms long (very old school) to stubby/chopper length at 213cms.

Some shorter boards also appear to be chopped off at the tail when in fact they are just shorter, and with wider tail/ platforms under the feet. There shapes either work or don't, according to the rocker line working with the board width and profile and rails, and with their size and float then matching the weight of the sailor.

So you can only compare like with like.
If you have two boards the same length then maybe, just maybe, you can start comparing rocker line and tail kick with a straight edge.
If widths are also the same at various points then that rocker line comparison might tell you something - where rockerline was the only variable.

But, actually, you'd be better testing those same boards side by side on the water. And that's true of most wave boards - where we tend to test boards of similar volume in different conditions, and with different weights of sailor.

The bench mark for wave boards is probably still, volume followed by width. And then followed by length. And then followed by rocker line, rail shapes, tail kick, and probably with some new method of measuring tail width.

if you have continuous rocker it's very hard, you only have to move the measuring point a bit and you get a completely different result. So it's almost meaningless, overall rocker nose to tail is all you can measure with any confidence, but that's not going to tell you much about how 2 different boards perform.
It's much more clear cut when there is a flat planing area. You can see where nose and tail rocker starts and how much there is of each.

thanks So measuring in flat floor is not accurate even for tail kick due to different lengths characteristics . There are some recommendations with a straight ruler like ""The amount of tail rocker and nose rocker is measured with the tangent at xmm(like 1000 mm) from the tail ''but i guess it could be board brand specific
I dont know how planchemag did the rocker measurements and compared different boards and how accurate is this comparison, maybe depends on the method used and those numbers could be different to the measurements of another magazine.

yes a meter sound like a reasonable distance, But I've no idea how standard it is. I guess tail rocker really comes into play when planing, so it should be measured relative to the planing area, which will vary according to all sorts of factors.

Tried to measure tail kick fanatic grip 82lt and got 11mm on the floor and at 1 meter off tail 8 mm with the straight ruler In order to reach planchemag magazine measurement 2 mm i ve had to move the ruler further back from 1 meter

Standard 0mm measurement is 900mm.
If all boards are measured like this it becomes consistent.
This makes it very easy to compare numbers.

Again Ive found chop tails (my bad- I know they designed tail fwds ) - distort rockerline measurements a bit vs older longer 225-230 shapes ... so say that 0mm at 900mm , on a shorter tailed board - that ground zero is further up the board than a longer say 225/230 rockerline .. and therefore distorts the entry (nose) rocker lift off points a little ... ie starting way earlier in comparison to longer shapes ....

But that only matters if your measuring yr very current boards (rocker) vs a board of 3-4 years ago (probably longer rocker / longer tail etc ) ... and trying to figure how the rockerlines compare ...

The 900mm zero point is just a measuring process.
Once you have the rocker line numbers and insert positions you can overlay completely different boards using what ever parts of the rocker and board geometry are relevant.

I guess one good reference point to compare 2 boards rocker line is the location of the front footstraps.
If the flat area start some few cm before this point and extend further toward the mast track then the board would probably promote front foot riding.
If the flat area stop at de front footstraps but start around the back strap, then the board is probably promoting Blackfoot riding.

The addition of the rocker value below the back foot and the scoop value measured some 60 cm in front of front strap, will probably tell how "wavy" or "surfy" is the board.

But of course this also depend on vee/concaves + outline + volume flow... If it was simple we all would be shapers but only a few are gifted enough...

In blasting boards it's quite simple . There is a metre of flat at the back half of the board . Usually about 5 , up to 10 mm at the back . Usually 5 .
I would imagine on a wave board it's not so simple to measure . On a fast board it's the last third that does the work . On a wave board it's at least two thirds ? Some pics I've seen people sinking the nose under a lip . WOW !
Don't wave board rocker lines ideally match the intended wave face curve ?
Smaller slower steeper waves need curvier rocker .ect. .?
My type of sailing only uses the last part of the board . The front part of the board is there only to be able to use the last part of the board .
Slowly engaging a full rail is something I've never done , apart from jybing .I've felt it and I understand what it is but I've never pproperly surfed surf waves .
I've ridden plenty over head high wind swell but that's a different thing.
Sailing surf with surf rocker would be such a fun thing . I would think .