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Understanding rocker

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Created by scubaste Two weeks ago, 5 Mar 2019
scubaste
WA, 155 posts
5 Mar 2019 8:32AM
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Hi chaps
I am a bit confused about rocker, if anyone has any ideas about it.?
I have a Naish nalu 11'6" which has a heap of glide and paddle speed but also has a heap of rocker.
If I drop length to say 7'6" with say 2.5" of tail rocker 5" nose rocker its a totally different ball game harder to paddle less glide & paddle speed etc.
I was thinking of making a 9 ft board just for winter, I have drawn it on AKU shaper but as standard aku is putting over 3" tail rocker and 5" nose.
??
On a 9' board would 3" of tail rocker be a dog to paddle?

Scuba

colas
3008 posts
5 Mar 2019 3:35PM
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A 7'6" board being slower to paddle than a 11'6" is because of the ... length, not the rocker.

There is no way you could make a 7'6" paddle as fast as a 11'6" with just the rocker.

Paddling speed is in displacement mode, and has a speed limit proportional to the length of the board. Rocker plays a tiny role for paddling speed, but as rocker is so critical for surfing performance, you should design rocker only for the surfing performance.

In my opinion, a surfing SUP that paddles well is one that is stable enough for you to really apply power to your paddling and not lose speed by balance wobbles, and has water-piercing entry lines (nose pulled in with low volume rails and some convex hull). Rocker will not matter much, especially on short boards where you reach the paddling speed limit very easily.

As fore values, rocker is often the magical touch that shapers do not want to share. To give you an idea however, you have the total value of the rocker (front+rear) on all the gong boards, and the associated description to see if they are considered slow or fast rockers on a wave. 5+3 = 8" is quite flat for a 9', typical of a noserider.

scubaste
WA, 155 posts
6 Mar 2019 4:53AM
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Thanks Colas
Great description

LeeD
387 posts
6 Mar 2019 5:12AM
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Rocker is only one of several factors affecting displacement travel. Weight [yours and the board], width [shape of ourline], thickness and taper, length of course, paddle power and technique, chop or flat water as well as salt or fresh, paddle used, rail shape and volume as well as deck flatness or taper ALL affect a board's paddling speed and ease.

Slatz
NSW, 150 posts
6 Mar 2019 2:42PM
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Select to expand quote
colas said..
Rocker will not matter much, especially on short boards where you reach the paddling speed limit very easily.





Hi Scubaste, Good insights into it all Colas, but I have to disagree with you on this one. Rocker is incredibly important, especially in shorter SUPs. If you were to scale down a larger board that had a single stage rocker, lets say a 10'0", and tried to use the same rocker in a 7'6" for instance it would definitely paddle like crap.
We use 3 stage rockers on most of our smaller model SUP's; what this does is allows a flatter section through the middle of your board to generate more paddle speed and also speed on waves, especially if the waves are fatter. (Also makes is slightly more stable as more board is in the water)
You then have to add another aspect which is what do you want the board for.
Do you want it for summer mush? then the rocker will be flatter (less nose entry and less tail kick and more 3 stage rocker)
Do you want it for more powerful waves and more manoeuvrable? (More nose lift and more tail lift and more single stage rocker)

It is not as simple as simply inputting the nose and tail lift as these are not the rocker, the rocker is the curve between these 2 points

For instance I have 2 similar sized and shaped boards but the rockers are totally different. One is for more powerful point break style waves, whilst the other is for what we generally surf, which is sub standard.
I also have a third model with super flat rocker but added chute channels and a more parallel outline with more thickness in nose and tail. This is awesome is fat mush burgers, and is still manoeuvrable.

The image below is the summer mush burger rocker vs the more powerful point break model & in between model



This one below is basically the same outline board with 2 different rockers. They both go very different.


You can see on this bottom image that the light blue line is flatter from the middle moving towards the nose, yet has a higher nose lift

colas
3008 posts
6 Mar 2019 3:46PM
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Slatz, you are speaking of the influence of rocker once on the wave. That is totally different.

I was speaking of paddling, in displacement mode. As long as the board tail is under water (and on short SUP my tail is well 4" under water), the amount of rocker does not change anything. Too much rocker would slow paddling speed if it was so extreme as to reduce the water line length (tail out of the water).

On long SUPs (14+), too much rocker can slow a board down, as the speed limit is higher, and it is possible to have the tail above the water with too much rocker.

Just removing your kick pad will have more effect on paddling speed than rocker. Or just trimming it like I did on this board:

before:



after:

supthecreek
1682 posts
6 Mar 2019 8:15PM
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Not all fancy science in my reply, just my personal experience with similar dimension boards.
Both are basically traditional outlines
Both boards surf and paddle very well....
Neither one of the has much "glide" with my 100 kg on it, but IMO no shortish board will have much glide at weight x 1.3
but there is absolutely no question in my mind which one is easier paddling into waves.

Board # 1
9'1 x 31 at 136 L
Performance rocker, decent tail rocker, good nose lift

Board # 2
9'0 x 31 at 133 L
Very flat tail to nose... very little nose lift or tail rocker

Board #2 is MUCH easier to paddle into waves of any kind.
Easy paddle speed
catches any kind of wave with less effort
easy speed on the wave
Definitely have to pay attention when dropping into a steep wave, but not really an issue if you plan for it.

scubaste
WA, 155 posts
6 Mar 2019 8:18PM
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Thanks for the input Slatz, and Colas ,
i think i might try a 3 stage rocker with a flatter curve between the nose and tail kick.
I might have to design a lowish rocker board on aku then do a subtle kick.
Just need to keep the rocker flowing though.
Cheers
Scuba

scubaste
WA, 155 posts
7 Mar 2019 6:43AM
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Select to expand quote
supthecreek said..
Not all fancy science in my reply, just my personal experience with similar dimension boards.
Both are basically traditional outlines
Both boards surf and paddle very well....
Neither one of the has much "glide" with my 100 kg on it, but IMO no shortish board will have much glide at weight x 1.3
but there is absolutely no question in my mind which one is easier paddling into waves.

Board # 1
9'1 x 31 at 136 L
Performance rocker, decent tail rocker, good nose lift

Board # 2
9'0 x 31 at 133 L
Very flat tail to nose... very little nose lift or tail rocker

Board #2 is MUCH easier to paddle into waves of any kind.
Easy paddle speed
catches any kind of wave with less effort
easy speed on the wave
Definitely have to pay attention when dropping into a steep wave, but not really an issue if you plan for it.



Thanks supthecreak
I know what you mean, the flatter the rocker the easier to paddle, and the easier to get on the wave but harder to turn.
Its just getting the best of both worlds compromise that's hard.
I might go a 9'5" with about 3" tail and bout 6" nose I might see if I can stage the rocker or over that length I thin conventional rock might be the go.
Thanks
Scuba

supthecreek
1682 posts
7 Mar 2019 7:42AM
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Mine turns super easy.... very loose board, that's why I like it.
Putting up a vid on my Youtube channel right now. Brought it to Portugal with me

Slatz
NSW, 150 posts
7 Mar 2019 1:03PM
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Select to expand quote
supthecreek said..

Board # 2
9'0 x 31 at 133 L
Very flat tail to nose... very little nose lift or tail rocker

Board #2 is MUCH easier to paddle into waves of any kind.
Easy paddle speed
catches any kind of wave with less effort
easy speed on the wave
Definitely have to pay attention when dropping into a steep wave, but not really an issue if you plan for it.


Yep exactly Supthecreek. Flatter rockers definitely paddle easier.

For a 9ft board 3" tail is fine, but if you are looking to surf steeper waves with a bit more juice I would increase nose to 6"

benjl
203 posts
7 Mar 2019 1:28PM
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Yeah I'd agree, even my 8ft board has 5.5" nose lift

scubaste
WA, 155 posts
7 Mar 2019 2:58PM
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Select to expand quote
Slatz said..

supthecreek said..

Board # 2
9'0 x 31 at 133 L
Very flat tail to nose... very little nose lift or tail rocker

Board #2 is MUCH easier to paddle into waves of any kind.
Easy paddle speed
catches any kind of wave with less effort
easy speed on the wave
Definitely have to pay attention when dropping into a steep wave, but not really an issue if you plan for it.



Yep exactly Supthecreek. Flatter rockers definitely paddle easier.

For a 9ft board 3" tail is fine, but if you are looking to surf steeper waves with a bit more juice I would increase nose to 6"


Awesome guys
Thanks for the input



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"Understanding rocker" started by scubaste