Design strategy question for the shortboard gurus: I’m looking to make myself a thruster/shortboard shape to use in place of my fish (which has become my “shortboard” over the past couple years). Haven’t owned a thruster for about 3 years now. I’d say intermediate surfing skills (probably pretty “front foot heavy”) with moments of good karma/luck in wave selection, and hence performance boosts (read: “good days”). 6’2", 200 lbs. My fish is 6’2" x 21" x 2.9" and I love it, but I’d like to experiment with an appropriately-sized thruster after time away from that type of board. Anybody have dimension suggestions to help start me out here? Thanks in advance…
Hey,
I own self-made both, but my modern fish (6’2 x 20.5 x 2.7) is a semi-thruster…two bigger fronts with a smaller center…works great in short wall’d trimming but doesn’t pump very well. I ride big guy thrusters mostly. How you want to ride is the most critical design input element. Assuming you dont want to pump hard to have fun/performance, go with a 80’s type board…low rocker, wider, thicker…look at a Channel Islands Mongrel online…Tom Curren, the master flow artist, rode low rocker’d boards throughout his career. The low rocker will benefit your front foot type approach and its simply a faster/funner board especially in average surf. Low rocker would be around 1.5 - 2.0 inch tail rocker, 4.5 - 5 nose…medium rocker about 2.0-2.3 tail. Heavy rockered shortboards are not as fun in average surf, IMO.
Most of the stuff on the racks wont suit you except maybe a CI Flyer.To maintain speed, use a deep single concave in heavily rocker’d areas (CI Flyer). For your weight, go with a 6’6 +/-2", thicker and a little wider…mine are about 19" wide. If you can build/get an EPS/Epoxy even better…eps is great for heavier guys… I weigh 175lb and Im 40 y/o and I ride 6’4 - 6’6 eps/epoxy…thinner b/c of the extra float. I also own a 6’11 heavy semi-gun. Hope that helps.
Thanks 'crafty. Great input. I was just out back playing with a 7’3"A Superlight. It looks “medium rockered” right off the bat. I was drawing some lines out and was thinking:
Length 6’9", Nose 13", Wide Point 20.5" (2.5 inch back from center), Tail 14.5"
Will this work? Or is this TOO wide (esp @ nose)? On this type of board, what would you say is more important for carrying speed, width or thickness?
Thanks again,
Matt.
Hey Matt. sounds like you need a big guy hybrid fish… that nose dimention doesn’t sound to narrow to me. maybe to narrow… I really like that 7’3"A blank works great for mini longboards, eggs and low rocker hybrids. I made this 6’-6" 20.25 x 2.675" ( blank 6’9"A) board for a friend that is about 15lbs lighter than you. it’s kind of a early 80 type board with a really low nose rocker, wide point up from center… my friend says he really likes the way it rides… the other picture is a 7’-2"x 21.75 x 2.75 big guy hybrid/80’s sort of board… are these something along the line of what you are wanting to build.
hey msacht - just made a thruster - 6 9 x 20.5(wp @ 2.5 back from centre) x 14.5t x 11nose. I’ll tell you how it goes - by the way I’m 6 2 and 225 lbs. Your nose sounds wide but ok if you like a hybridy shape.
Thanks guys. Silverback, lemme know how it goes for sure. Here what I just cut out last night:
6’9" 13 x 20.5 (2.5 inches up) x 14.25
Looks “mildly hybridy”. Should I put a single-to-double concave in it? Keep it flat? Here we go…
Hey Matt,
My PC is in shit mode so I gotta borrow others to visit Swaylocks.
“Will this work? Or is this TOO wide (esp @ nose)? On this type of board, what would you say is more important for carrying speed, width or thickness?”
ROCKER! Then width.
Its amazing how underrated rocker has become…or has always been…???
Anyway, you haven’t mentioned how you plan to use the board.
How do you like to surf? What conditions? Weak or powerful?
Until you can accurately answer these critical questions you may end up with a sub-optimal board. The “A” blanks are great for making low/med rocker boards.
A flatter rocker board would benefit the least from concave…its already got a flat fast bottom. I like to use concaves but you gotta know how to do it right…the trick is to use it in places that have the most rocker without friggin up the overall shape…for a regular shortie that’s usually around the front fins and between the feet. I find that wider noses while great for paddling in, are bit detrimental in juice…lots of drag along the forward rails tend to catch. A good big guy reference shape is a Rusty Desert Island…hybrid shape.
All said, most design features are important especially when taken as synergistic sum, but rocker, fin config and volume are still the most critical design features IMO…
Thanks ‘crafty. The blank is actually a custom rocker 7’3"A (+1/2N, +1/4T), so perhaps it would take a little more kindly to a bit o’ concave. Question: if a hypothetical blank has 5" of nose rocker, and 2" of tail rocker, wouldn’t the greatest amount of rocker be in the front 1/3 of the blank? It looks as though the “apex” of most stock rockers appear just north of the blank’s widepoint. Is this an optical illusion? Anyway, (put simplistically) it sounds like you want to put a shortboard’s concave at the APEX of the board’s rocker, then taper to either double concave, flat, or vee as you move south toward the fins. Does this sound rational? Thanks again for the input.
Question: if a hypothetical blank has 5" of nose rocker, and 2" of tail rocker, wouldn’t the greatest amount of rocker be in the front 1/3 of the blank?
I guess youre right but I dont really look at it that way. I don’t put all my faith on numbers…Ive gotten to the point where I shape by mostly eye and check/validate with numbers. Bottom rocker utilizes curves with different radii of curvature…not the most straightforward concept in surfboard design but the most important.
It looks as though the “apex” of most stock rockers appear just north of the blank’s widepoint. Is this an optical illusion?
The “APEX” is often debatable and elusive. Its better to approach it as a transition from entry rocker to exit rocker and the location of this transition (somewhat flat/elusive on many boards) should theoretically be placed between the riders feet for std shorties…thats about 6-10 inches behind center. If you understand Greg Loehrs Theory of Pitch then youll understand things better. BY FAR, the easiest way to find the transition is to look at the bottom/stringer with the board right side up…it sounds corny but its real…much harder to see it with the bottom up…talk about optical illusion!
Anyway, (put simplistically) it sounds like you want to put a shortboard’s concave at the APEX of the board’s rocker, then taper to either double concave, flat, or vee as you move south toward the fins. Does this sound rational? Thanks again for the input.
Yup, that’s one of the keys to maximizing a concave’s effect…not only are u channeling water out the back but youre creating a flatter faster centerline rocker, or at least reducing bottom curvature at a very critical section of the board…too curvy and pressure drag shoots up and you bog. For a backfoot surfer I’d move the concave back further. I’ve looked at dozens of Al Merrick’s shapes during my research and this is consistent in his boards. The M4 has a pronounced tail flip and he extends the single concave thru this section and out the tail block.
I admit that I dont have a validated grasp of single/double diffs…here’s my take…a single adds more lift and thus in power would make a board too squirty and lose control (I recently took a tongue depressor and added concave to it, then I tested it under a running faucet to prove the lift theory…there is a dramatic diff between the concave and convex sides…better than the spoon test). A double reduces a singles lift but maintains the channeling out the rear…at least thats my theory.
On a bigger board like yours your foot placement may not be as precise but as long as your keep that bottom curve smooooooth you’d be ok. BTW, Im currently reworking my main shorty…peeled the bottom glass off and went from a double/Vee bottom to a single concave thruout the bottom and Im reconfiggin the fin system to include center fin fore aft adjustment using Lokbox. I can also vary front fin toein (very sensitive parameter) using FCS FG series or regulars. Im so stoked on this appoach…I’ve been on a perpetual epiphany for about 4 months now and applying what I’ve learned. Listen to Greg Loehr, Bert Burger, Blakestah very carefully, after a couple of years you’ll know a hell of a lot…I owe a lot to them.
Here’s a little scary nugget…you can make the best shape on the planet but if youre fin config is off you end up with mediocrity.
Thanks tons, 'crafty. Sorry 'bout taking so long to reply (buddy got married this weekend in La Jolla). Great to hear your take on this stuff. I’ll keep you posted on this board as it moves along in its development…