# Blank length cut affecting rocker measurements

I posted on here a couple days ago regarding this and then deleted it cause I thought I figure it all out....wrong... This thing is messing with my mind.....

So I got a 83h us blank the other day blank measurements are 8'3x3 7/16 thick. Nose rocker 4 3/16" tail is 3 5/16"....here is my problem.

I am making a 7'2 X 3" thick with plus or minus 4" nose rocker and nearly 1 5/8" in the tail. to get this rocker out of the blank I have, I figured I'll cut 13" off the tail. When I measure the tail rocker on the 8'3 at 13" up where the cut will be, the tail rocker is a tad over 1 5/8". when I measure rocker from the center point of where the 7'2 will be, I get tail rocker #'s at 2 1/2"!!! Same point on the blank where the tail rocker is measured, but center is shifted farther up cause of shorter length. thick point is farther back, but I can foil this out to make the thick point a tad ahead of center(where i want it to be).

Question is, if I foil out this thickness behind center, will tail rocker decrease to where I want it? It makes sense to cut most of the length off the tail to decrease tail rocker, right??? what am I over looking? this thing has got my brain twisted up like a knot.  I hope this makes sense, and thanks in advance.

Hey Asteve, In cutting off the last thirteen inches you have moved the apex of your rocker. It seems this will take a lot of planing to achieve your goal and may get into overshaping. The point you are measuring at is already into the entry rocker of the stock blank. Draw the two rockers out and their respective lengths, place one on top of the other on the page. This may help to illustrate the two different arcs. To flatten the shorter radius by drawing another straight line through the curve you will see the material loss and so getting to soft foam. You will need a different blank to maintain any sort of thickness. Hope this doesn't confuse. Good Luck.

Make yourself a rocker template first, the place it on the blank.  Slide it along until the template is closest to the blank’s curvature.  Cut off what is past the template.

Start with your idea and keep it.  After some time of riding it, decide how you like it, then consider what to change.  If you are following the blank, not your idea, and not remembering the measurements of the last one, you are walking around in a fogbank, not really knowing where you are heading.

Always go for accuracy.

Rocker IS not just in the nose or tail.  It can be and most times IS thru-out the blank.

I just posted on the “what are you working on now thread” my latest 7’0"    I included the rocker numbers.  First three numbers are 12" steps from the nose.  center apex is 0.  last three numbers measure 12" steps from the tail.  These are good numbers to start with, for a semi-step up.  Lower the nose a touch for a summer fun board.

Hey thanks everyone for the responses.

Tblank,

I get what you are saying. When I measure thickness of the blank 13" up from center where the new center for the 7'2 would be, the thickness is about 3 3/8. of course behind this, the thickness increases to 3 7/16". My thinking was if I remove the foam behind the new center to get it to a point equal to or less than 3 3/8" thick, the "apex" would shift and my tail rocker would decrease.  I might just have to bite the bullet and get a new blank.

Templates and rocker numbers between the two end points are equally important and I agree, but I am just trying to see if I can get these numbers to fit into the blank I have, or else I will have to get a new blank

EDIT: Just something to add... I checked US blank's catalogue and I cant seem to find a tail rocker this low without moving on up into 9ft+blanks and chopping a ft off of either end. Here's question number two then...

If I cut out the stringer, and do my own glue up, how much rocker could I get away with decreasing in the glue up? My plans now would be to cut 6 in off the nose and 7 off the tail. Natural tail rocker at that point on the blank is at about 2 1/2" I believe. New stringer would be 1/8" or LESS redwood or cedar. thanks again guys

Asteve, Cutting out the stringer will solve all your problems. You will be able to cut your own and bend the foam to match. This way the thickness can be maintained. It seems the only other way is to sacrifice that thickness. In the future, what Everysurfer said about a rocker temp is spot on. Try to get into the habit of making rocker temps and working with them. It is to me the best way to clarify the bottom curves.

hey thanks tblank and everyone else,

I got some redwood while I was in  town this afternoon. Any preferences on glue to use? Is there a certain amount of bend I can't put in it? obviously there will be a point where it breaks, but I am not going to go that far :)

Hey Asteve, I'm assuming this is a poly u blank from US Blanks not styrene. If so, you can use regular old lam resin or epoxy. That's what Clark used for glue ups. Wood glue will work also. If this is a styrene blank, you might want to consider white Gorilla Glue. I'd stay away from five minute epoxy because you want a longer working time to get it aligned. As always, Good Luck.

Thanks Mr Tblank,

you assumed correctly. It seems like US blanks uses a white wood glue.  I'm probably better off using Lam resin. I should probably coat the stringer with a thin coat of styrene+pe mixture for a better bond. I do this with wood fins at least, to prevent the wood from absorbing all the resin and leaving with a drylam on my fin. Good idea, bad idea, waste of time???

Hello Asteve, Styrene is nasty s\$%^ and I'll use it only when I have to. You can thin out some lam resin and "seal" the stringer both sides with a light coat. Let it go off and then go for the foam.But.. if you have a process that works for you stick with it.

Here's one for Ya Asteve, Go to the Greelight surf supply site and click on the blanks link. Next click the EPS blank thread and watch the glue up video. A handy item to have around is the industrial type saran wrap they use for shipping. This makes a quick easy clamp once the foam and stringer are lined up. Luck.