Rocker measurements

General Discussion
21

Sufding, that is my favourite board rocker curve, give or take a mm here or there. It’s a magic one for sure. I like to also look at the radius of the curve in the centre where the nose and tail curves meet (Boardcad). Short boards scaled to 6'0 size appear to have a range between 22'-24' radius for curvy boards and 30'-32' radius for flat rockers, while 26'-28' radius is in the middle for an average all rounder.

 

I think I understand Greg's theory of pitch, wave speed and size increasing with increasing tail rocker. But I still don't really understand nose rocker. I suspect nose rocker is more related to the curve of the wave and style of surfing (as Mick suggests in the quote above) rather than pitch. But I don't know.

22

Surfding’s puter printout is a gem of information however simple conceptual diagrams such as this are good at illustrating a point.

applying the above diagram to nose rocker the top one will feel like a more highly rockered board, what I think the bottom one does is give a low nose rockered board some anti-pearl qualities.

Taking my Pancho and Macca nose rockers as examples - Pancho 5 1/2", Macca 5 3/16" so the Pancho has more nose rocker. One foot down is a different story Pancho 1 9/16", Macca 1 7/8" or easier in mm Pancho 40mm, Macca 48mm.

One foot down from the nose has the opposite situation - Macca board more nose rocker than Pancho and I think this is the one that counts but the Pancho has some anti-pearl flip. This makes the Macca board like John’s top diagram and the Pancho board like the bottom diagram

following on from the Macca board having more “effective” nose rocker than the Pancho and taking the rest of the board into consideration the Pancho board has heaps of tail rocker.

Neither the Pancho or Macca board have “kick tail type flip” (just as an aside I think Fanning’s board does)

So it is IMHO meaningful to sum the 1’ down from nose plus total tail to get an overall combined rocker.

ie nose 1’ down + tail tip = combined rocker

Pancho 40 + 73 = 113

Macca 48 + 63.5 = 111.5

very very similar - within 1.5mm of each other and I don’t think I can tell a 1.5mm variation in rockers that are otherwise similar (however these aren’t).

I think so too - although combination rockers are near as dammit the same - the Pancho comes in with substantially more tail rocker and this is the one that gives it a very high rockered feel. Before I measured the Macca I thought it was more like 2" of tail rocker coz it behaved like a much flatter board under my feet after jumping off the Pancho.

I’ve also been fortunate in using/borrowing a couple of Josh Dowling shapes from an identical template in good waves at the same location. Overall rocker about the same but one had high nose and low tail and the other low nose and high tail. The high tailed one felt like a high rocker board.

 

So finally onto Claude’s question: These are just two pairs of experiences but all the boards mentioned above are good - I think this is telling me that if a board has say high tail rocker then to produce a nicely balanced board which doesn’t have a banana feel then the nose should be lowered in a complementary manner (and vice versa)

My Pancho and Macca boards make a great 2 board HPSB quiver due to their complementary rockers, however this was a happy accident. I had no idea what I was getting with these stock shapes.

 

I just preview read this for posting and good grief I do write some bullshit sometimes. Surfboard design seems to be like justifying happiness with a calculator. Oh well, hatever adds to my surfing experience is all good.

23

I think I learnt most about rocker curves when I started computer lofting curves.  Rather than meeting curves at rocker low point the way almost everyone else does, I just use end points and vary the curvature at the tail and nose so the curves meet where I want them to (at board mid point for my mid rangers).  When you tweak the nose, then the tail moves up or down and the rocker low point moves fore and aft  You have to constantly adjust each end incrementally and try to get to a sweet curve.  Of course, you can just add more curve segments in order to meet specs, but my “thing” is smooth, unsegmented curves for rocker and outlines.

Of course it’s computer stuff, but I don’t think they differ must from the sort of curves lofted from, say bicycle chain hung between points, or a curve of plastic or ply.  You can’t move the ends in isolation - the curve low point shifts, too.  You have to constrain the curve with nails (add multiple curve segments) if you want to meet certain numbers.

PS Surfding - sweet looking board. Love the curved outline, fast rocker combo.

24

Hi all,

My problem is not measuring the rocker, it’s planning it into the foam block.

I’m using 7’5" rectangular EPS blocks (pre shaped blocks are unavailable where I live and polyurethane is too expensive and rare) the problem is the blocks are only 2.75" thick!! so I am restricted to a rocker of 2.5 or less, or am I? 

 

when planning in a rocker do I just use the electric planer on the block to reach the desired curvature or should I also bend the block(if yes, how?)

or should I just get thicker blocks?

 

Thank you!   

25

i like nose entry at 1 foot down around 25 to 30 mm

i shape a 3 stage rocker in other words

it is flatish through the middle with gentle curve in the tail to a bit of flip in the last

nose tip numbers dont mean much overall as you can shape the equiv of a 4 inch nose but makeit 5 just by flipping the tip . can be tricky to get just right and often eyes play tricks on you

i think it about time i make a rocker stick

26

Hands down, this is the best thread I have read on Sways in months. Thanks to all of you who took the time to share your thoughts and theories about rocker. One thing nobody has addressed yet is the standard rocker measurements cut into every close tolerance blank (at least the PU ones I am using). For every board I've shaped I always print out the spec page from the manufacturer of that blank. The rocker numbers are probably not exact, but it gives you a good starting point, then you know where you can adjust the thickness without disturbing that continuous flow. The rest is done with the eyes, I have yet to make a rocker stick but it's on my to-do list.

27

I work with Rocker Sticks base on Deck Rocker and have all my blanks custom glued with my rocker for a given model.

Too see so many professional board builders buy blanks without the proper rocker makes me wonder?

Rocker is one of the most important aspects of board building. All the fancy vacuum bagging and Hi-Tech materials is wasted on a bad rockered shape.

For my shortboards I have 5 different rockers for different conditions.

Nose, Tail, Center Point, Foil Thickness all varied for the desired charcteristic of the surf break intended for the projected design. Having good surfers for feedback will help you to be a better shaper.

In creating the right rocker from a 2.75 thick EPS Block do the following:

1. Make your rocker stick with you desired thickness with 1/8 extra on the bottom side of the rocker stick.

2.Take your rocker stick and trace it on to 1" thick piece of EPS Lenght of desired board with the width of the   desired rocker.

3.Once you cut this out you have a flexible rocker guide.

4. Cut out two pieces of mansonite length of the rocker stick and the thickness of the EPS block in question.

5.Blend the EPS rocker stick until it fits the masonite rocker blank ande trace it will a sharpie.

6.Place the two masonite blanks together and cut them out making sure you leave the drawn line visable so you can block the rocker guides even to the line.

7.Pull the two guides apart and drill a 1/8" hole evey 10 inches staring 1" from the tips.

8.Place masking tape on the edge that the hot wire will travel.

9.Attach the rocker guides to each side of of the eps blank.

10.Hot wire the deck line first

11.Hot wire the bottom rocker next

12.Split the blank down the middle with a straight taunt peice of wire and place on the center of the blank at both tips. This bow should have enough weight so that when you turn on your variac it cuts straight and even.

13.Light sand the cut sides of the blank before applying glue (This will help prevent gassing along the stringer when glassing)

14.Glue one side of the stringer and one side of the blank place the two glued sides together

15.Proceed to glue the other side of the stringer as well as the remain half of the blank

16.Clamp the blank starting from the ends working your way down (It's easier to start from the tail and work your way to the nose)

17.Make sure you line everything up to your deck line stringer. That way you only have the bottom side of the rocker stringer to trim even.

18.You will be starting from a pefect deck rocker. By planing the bottom and checking thickness every 3 inches you will obtain the perfect bottom rocker. Remeber the deck line is your reference point. If the perfect foil the rockers will flow and match.

* My Make glue up is Epoxy with Microballons for glue up of stringer. I have used Roo-Glue as well and it's cheap.

Hope that helps?

Surfding

28

Rafis I made a check list for you see above reply to RAND.

Yes you can make a blank with the desired rocker from a thin block of foam if you follow my steps.

I've made 100's of them.

 

Surfding

29

That is a really awesome post!

three small problems:

  1. I don’t know how to make a rocker stick

  2. I don’t have a hot wire, is it possible to make a homemade one?

  3. and most important how does gluing the two pieces of the blank together makes a rocker higher than the original blank width

sorry if my questions are lame, but in Israel the resources for backyard shaping are minimal and shop shapers tend not to share knowledge.

 

thank you,

30

I'm trying to share with you so you can make a good board.

You bend the blank to fit the the rocker th stringer holds the rocker in place..

 

Send me you address by a Private Message and I will mail you a plan in full scale. Including the rocker and outline!

And give you some instruction on hot wire. Maybe some diagrams to help you understand?

 

Surfding

 

31

man thanks so much for the info! I will send you my address on private.

I’m sorry for the “not sharing info” remark, I meant the shop shapers here in Israel, not here on the form

32

hey ding i also agree that close tolerence blanks do not allow for suitable rockers

eg. to shape a 6 footer with the roker width and thickness i like, i need a 6 7 blank

i used a kneeboard blank for a fish and there is way to much entry in the nose by the time you get it right your down to 2 and a half thick

so there is no chinese boards with my personal dimension, i have created my own market creating rockers that suit the local waves

33

so there is no chinese boards with my personal dimension, i have
created my own market creating rockers that suit the local waves

Silly you got the right Ideal. I design my rockers base on where the board will be surfed and the conditions that are intended. MASTER ROCKER AND MASTER YOUR LOCAL MARKET!

Sorry for yelling!****

 

**Johnny Rotten
**

34

I wrote this up a few days ago but couldn’t seem to get back to posting it….. hopefully useful. Sorry if it’s long winded.

 

When calling out rocker numbers simply saying a board has 5 inches in the nose and 2 inches in the tail really tells little about the rocker curve at all. The over all rocker curve is critical to how your board performs.

 

Tip nose rocker in particular is not nearly as important as entry rocker.  Entry rocker is typically the 12” mark from the nose tip. 

 

The wave face doesn’t usually interact with the forward 12 inches of your board but the tail of your board is always in the wave… unless you’ve launched air… so tip tail numbers are important.  As well it’s good to know what the rocker numbers are through the fin or fin clusters, so 12 inches from the tail tip is good to know too.

 

It’s been maybe 5 years since I’ve done much with the standard short board but shooting for not more than 1 5/8 inches of entry rocker on short boards 6’ to 6’6” was the norm. The tip could be 5 inches more or less, didn’t matter too much but for paddling, catching waves, how the board would trim, the entry rocker will be the number to worry about more. 

 

Boards up in the 7 foot range the nose rockers don’t need to change much.  The tip may be over 5 inches but entry at 1 ¾ is plenty.

 

For the low rocker boards or alt boards say 6 feet and under the nose tips are maybe 3 ¾ inch with entries of 1 inch or maybe 1 1/8. 

 

And long boards… how much entry rocker will play a big role in how the board will paddle, catch waves and trim.  It’s typical for 9’1’’ long boards to have 5 inches of tip rocker and you may find more than 2 inches of entry rocker.  You do engage the forward portion of a long board so how the nose tip and entry numbers work is bit more critical.

 

Tail rockers can tell you more about how a board will ride. Of course outlines, rails, foam volume, foil all play together but here are three boards, make that 4, with corresponding tail numbers of 3 ¼, 2 7/8, 1 ¼ and 3/4 . But that says little compared to the rest of the story below.

 

8’6” 2 +1 Tanker.  Tail tip = 3 ¼. Tail at 12” = 1 3/8

 

7’2”  Fun or big guy tri.  Tail tip = 2 7/8.  Tail at 12” = 1 1/8 but note another number. At the back of the back fin.. 2 inches.  So this curve changes 7/8 in the 7 ½ inches from the 12” mark to the back of the back fin and another 7/8 in the last 4 ½ inches of tail length.

 

5’8’ Fish.  Tail tip = 1 1/4. Tail at 12” = ½

7’0 Hull. Tail tip ¾. Tail at 12” = 5/8.  Note this curve changes 5/8 inch in the 2 and a half feet from the center of the board to the 12” tail mark then only 1/8 in the final 12”.

 

 When thinking about rocker numbers looking into more than just the tips is a good idea.

 

D.R.

35

Nice post.

You reminded me.  I got told early on not to just put a curve between the rocker low point and tail, but to add a little “belly” to the curve (1/4-1/8") because it makes for a faster flow. Seems to have worked for me over the past 5 years. I think your numbers reflect this, too, particularly the 7’2".

36

Awesome post!  Dennis, could you shine some light on traditional longboard nose and tail rockers? 

37

Dennis -

Yes, thanks.  Great info there.  I'm taking notes. 

38

Thanks guys.

 

For me, the bottom curves of boards with shorter lengths it’s fine to have rocker lines that get elongated or flatten forward of the fin area then accelerate out the back… exhaust.

 

I guess my old Wilderness/Greenough days when I didn’t measure rockers but instead used a two foot level to make sure from the tail tip up the length of the level was dead flat is to much a part of my basic design heritage.

 

As for traditional long boards… think flat, or low.  A nice long and low curve that has a little more curve forward than aft.  Traditional nose rider rockers are reversed, more tail curve than nose curve.  Loads of rocker in long boards is way over rated… IMHO.

 

BTW, integrating your deck curves with your bottom curves is one good trick. It’s not just about the bottom.

 

D.R.

39

Have the same problem here in Sweden. Invented a solution which I have been using now for some years and a number of boards.

The trick is shaping down the block to right foil. Thin nose and tail as desired. Then I put the board on racks and insert a button on the tail and nose. Put a wire trough the button trough the board. Attach a line to the buttons and bend the whole board into desired rockercurve. Try moving the racks for achiving your prefered curve. Then you laminate as usual. Just remember that the rocker will straighten out some (about 1/2 ´´ forward and 1/4 tail) so have this in mind.

I found this technique working quit well and very time and money saving.

Give it a try:)

40

thought i would bump this thread I think it real helpful. i just started shaping a 6'2 low rocker board, i am looking at something abit like the firewire Sweet potato but maybe not so extreme http://www.youtube.com/watch?v=6X3ywU0Jr-g

I aiming for 3 3/4 nose gentle curve to just behind center and then 1 tail with flat bottom into a strong vee and double concave alittle like a bronzer with a quad set up . I am planing a step-deck to give board move volume aim at 4 1/4 thick but droping the rails to normal board thickness around 2 ish at think point in center

wht your thoughts guys  

antony