Hey DrStrange,
I posted some numbers way back and also corresponded by PM with quite a few shapers about rocker
numbers. I have re-submitted the numbers here, sorry if it runs a bit long, but the explanation is quite
important to get the rocker just right…
True Classic 5’6" fish
N: 3-5/16
12: 11/16
24: 1/16
C: 0
24: 1/8+
12: 1/2+
T: 1-1/16- (where ‘+’ and ‘-’ are about 1/32")
Performance 5’6" fish
N: 3-13/16
12: 1
24: 3/16-
C: 0
24: 3/16
12: 5/8
T: 1-5/16-
Start with a horizontal line, find the halfway point, C, and spec the points: N and T are obvious. 12 means 12 inches from the nose or tail, and likewise for 24.
Best to use a long flexible stick, (spline) with good continuous wood grain. Floor molding strips work well, (those quarter round little wood strips that have no knots or wierd grain). Some use fishing pole blanks. I’ve used masking tape before but that took about 10 years to get my skills up. Better find a stick… …put weights on it. Do the front half separately from the rear.
The above numbers may seem a bit flat but this is what works for this length (I can suggest numbers for a longer fish). Rocker might get altered for thicker boards but most boards run about 2-1/4 thick to 2-3/8. I’m 170 lbs, and I have a couple 5’8" x 19-3/4 x 2-1/4 performance models that work quite well. I have a 5’7" that is great in bigger waves, it has the Vee hull. Most of these things have flat decks BUT pinched rails with very little vertical “sidewalls” especially at the water entry- kinda knifey.
…my suggestion is to start by making a 5’6" rocker template (female version, so it can fit to your boards) and then
decide how you want to scoot your 5’4" around. One bit of advice for true twin keels, they really do not benefit from any tail kick at all or flat-to-vee in the tail, they will just bog. You almost want to lay a straight edge along the last 20" of tail!
Bottom contour can run 3 ways and work quite well. Stevie/Stanley made them Flat-to-flat, and Slight belly-to-flat. Duff started with Flat-to-flat and later made some with concave-to-flat. Belik is all about concaves and started trenching a tunnel down the middle of his boards. I’ve met a lot of success with subtle concave (1/8") just ahead of the front foot and dead flat in the last 1/3 of the board.
Edges. Pavel used to joke: “it all works, everything works, that’s the problem”. I’ve seen sharp edge from nose to tail like Bunker and Mansfield rode, and they worked. I’ve seen Pendo do hard 45deg bevels for tucked rails and it worked. Belik uses chines all the time. I’ve seen Geppy have normal rails up front and hard edges for the last 2 feet and it worked. I’ve been doing standard round rails and slight beveled rails that transition to a hard edge Mid-Keel and they work.
So I guess the moral of the story is “pick your poison” (lol). Actually, just go with your instincts, your first inclination tends to be the correct approach.
Anyways, sorry for crapping-on, hope this helps.
George