# Entry rocker curve

I’ve been thinking about entry rocker lately and I suspect what I’ve used in the past may not be as ‘efficient’ as I had thought. This is gonna be tough to describe without a diagram but I don’ t have a clue how to make and post an illustration (picture’s worth a thousand words) so here goes anyway.

Imagine a 6’4" board with 5 1/4" nose rocker at the tip and 1 9/16" one foot from nose. Zero rocker being the mid point on bottom curve. Now a second board with 5 1/4" at the tip but 1 3/4" one foot from tip. Although the second board has ‘more’ rocker one foot from the nose, the curve in the first half of the board is actually ‘flatter’. I’m suspecting the second board with it’s flatter curve would actually ‘push’ less water and slide into waves more easily than the first board. Just don’t have the opportunity to put it to a test at the moment. Anyone experienced in this ?

Not too sure I understand your question, but if two boards have the same total amount of nose rocker, but one stretches that curve out longer (has less entry rocker a foot back, but a more continuous curve through to the apex) it should push less water at low speeds because the rate of curvature is less. Staged curves… high rates of curvature in the entry, but flat through the middle, tend to push more water when paddling.

Pat, when I start in on bottom rocker in the nose, the first thing I do is take a good long look at it and see where it is following what I want it to look like. Then it is to shape it close to the tip if it already has a great deal of rocker past center or if realitively flat rockered, start further toward center and generate the rocker I want out of that blank. It is a matter of seeing enough blanks and finished boards to have the “picture” in your head of what looks right for you

We’re finding that the gun intro (which is lower, like the latter one you describe) is smoother so it’s being incorporated into my mid-range boards too. The curve is progressive to the nose (same nose measurement), but the intro to rocker low point is slower.

On a related note, I’ve found that a little “belly” in aft rocker (rather than the smooth inflow that the nose side rocker has) helps with more speed.  Our waves typically have a bit of push in them.  People who surf mush might have different views.

Hey Pat;
I don’t know how others describe what you are talking about,
but the way I was taught was that the numbers you describe
are called acceleration of the curve. This works for tail rocker
as well as nose rocker. When I plan out a custom board order,
I don’t focus too much on the nose dimension, but the measurements
at 6" back, 12", 18" and 24". For tail rockers, I look at 0", 12" & 24".
The “flip” in modern nose rockers is mainly cosmetic, but the 6 - 24"
measures really defines the nose curve. With the tail the real measures
are not cosmetic, hence the 0" is the true tail rocker. If you watch old
pros like Jim, you will see them cut in the tail rocker by passes from around
the 12" and then the 24" area. Modern shortboard blanks have the
“flip” already in the blank, so if you move your template up or back you
can actually change the acceleration of the curve if you plane out to
the same finished dim. This is one of the “problem” areas of a lot of
CAD type design vrs. hand shaping which depends on the program to
draw the curve you want based on an end dimension. I hope I haven’t
confused you further…LOL

Thanks guys - good info.

Jim...do you order your blanks with "natural" rocker or do you order your own rockers depending upon intended use of board? Do you ever physically measure rocker or do you rely upon your expertly trained eye to determine when the rocker is right and you have that nice flowing bottom curve?

Modern shortboard blanks have the "flip" already in the blank, so if you move your template up or back you can actually change the acceleration of the curve if you plane out to the same finished dim.

This is one of the "problem" areas of a lot of CAD type design vrs. hand shaping which depends on the program to draw the curve you want based on an end dimension. I hope I haven't confused you further.......LOL

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