How much rocker for Lake Michigan

Okay . . . I'm starting to design/build my own board . . .boards actually.  I'm 51, 220 pounds, a beginner and will be surfing smallish Lake Michigan waves.  The two boards I considering are a 9ft 6" longboard and a 7 ft 6" funboard as outlined by Jack Young in his "How to build a hollow surfboard".  Only diff is that I will be using foam blanks and not building a hollow wood board.  Since the waves are smallish I suppose a smallish rocker on the long board (nose 3.5 in, tail 2 in) and funboard (same as other board) would be appropriate or am I thinking about this the wrong way?  Any and all comments are welcome!



I gotta think on this for awhile.  My mind is thinking Freshwater vs. Saltwater.  Differances en masse etc.

I made some boards a long time ago for Lake Michigan waves. One of their  complaints was that they did not like the boards that went fast and straight and out ran the waves ie flatter rocker and wanted boards that turned more and stayed in the waves longer, more rocker, “slower turnier boards”.  I guess you have to decide how you want the board to ride in what you have to work with.

Hey howzit? welcome to swaylocks and great lakes stoke.


There’s a million ways to go on this one… but I’d start off my saying the salt water to freshwater differences in flotation are marginal. yes you heard that right. marginal…


for Lake michigan waves in general  the biggest factor will be lack of push behind the board. shoaling coupled with weak windswell is the biggest culprit of our weak waves.


You want a bit of nose kick but flatter rocker through the guts of the board… what happens is the wave moves slower so it doesn’t “build” like on the ocean. nose rocker keeps pearling to a minimum but a flatter overall board curve will give you speed.  an analogy would be a water ski. nose flip.


don’t have to go thicker then on the ocean, but keep the volume out to the rails and keep them hard in the tail for release through the back and speed through slower sections.


go with the longboard… the learning curve of surfing the lakes is a longer one then our ocean brethren. get more waves, and also you’ll be surfing more smaller days then if you got the fun shape.


here’s my quiver of lake boards


and this is my fav lake Michigan wave… please dont ask where it is. :wink:



UP . . .thanks hugely for the info.  I was playing with shapes on Excel and the graphing capability.  On the 9' 6" long board I built in 5" nose rocker . . . starting from either 24" or 36" from the nose tip.  Is one preferable over the other?  As far as tail rocker was concerned, I built in 3" starting the rise 24" from the tail tip.  Is there something I should change from here.  I've enclosed a picture of the graphs.

As far as the location of the break you posted . . . it's probably far from the surfing crowds I encounter closer to Chicago ;o) . . . you've got to fight your fellow wave riders down here just to catch a ride . . . LOL!

Mahalo from Chicago.



Damn right. The difference in weight per cu ft is less than 1%. How much you ate for breakfast would be more of a factor in floatation

For the Great Lakes, you must also factor in the specific gravity of urine relative to freshwater – wetsuits.

Yes ,on the Great Lakes, I would imagine saving the urine for the water is the way to go.

BTW, those board diagrams are amongst the worst I’ve seen.

You really need someone to clean those up.

But as a new person here, you’ve got the right attitude.We build boards here.


As far as (nose 3.5 in, tail 2 in), those would be minimal  measurments for a short board, not so sure about

applicability to a long board.




I appreciate the welcome Otis . . . in the Great Lakes, by the way, the reason to save the urine for surftime or scuba is to keep the wetsuit warm more than to affect the salinity.

I'm not surprised that the drawings have a considerable suck factor as I am a complete novice at best, but I don't know why . . .  which is why I posted them.  If you have specific criticisms of the shapes I would really appreciate some direction here.  I'm all ears!


Thanks UP . . . but before you go through the work . . . I redid my "computer shaping"  . . . and don't be afraid to be critical as one of the previous posts was (and I took it as a well meaning gesture).  Comments . . . anybody?  Prefer the 3 foot front rocker (5") or the 2 foot front rocker (5")?



Hi Sammy,

It won’t be the first time I’m wrong, and maybe I am, but I notice a difference between California water and Tropical water.  Warm water holds more salt than cold.  I definitely float higher in the South Pacific than I do in Ventura.  I float higher in Ventura than in my pool.  Won’t matter on a longboard, but on a short board of minimal dimensions, it would.

Cold water is denser than warm water.  Seawater is denser than fresh water (32-35 g/L salt, parts per thousand, 3.2%-3.5% salt).

Of course, denser water would have a higher drag co-efficient. Warm water would cause some volumetric expansion of the surfboard’s core.

I still say urine is less dense than seawater, more dense than fresh water and affects wetsuit density.  (But the temperature of urine at 98.6 F would affect density relative to cold water at 55-68 F initially.)

What’s the airspeed velocity of an unladen swallow – African and/or European?

Maybe the wetsuit weighs more than a pair of surf trunks …


Hey Oldersurfer

ignore semantic arguments.


do you own a surfboard currently? or have access to one?


to copy a board with minimal changes would probably be your best bet to doing a satisfactory job…


after rocker you have outline, foil, and rails…  then glassing… then putting in fins, then sanding.


KISS would be my advice.


later this week I can get measurements off my 10’6"   that board is really nice for lake waves.


we’ve had good swell up here

Other more qualified commenters will show up I'm sure, but here's my two cents' worth.

Your plan shape has awkward curves, and your rocker has a huge flat spot in the middle. 

While nose and tail rocker are a tighter radius, there should be no flat spots in the rocker.  And the rails appear to have a straight or almost straight line between the center and the tail, then go into a round sweep to the tail. 

Look closer at proven shapes, you can learn a lot from observing successful boards.

Dave Parmenter has an interesting interview in The Surfers Journal this month, worth a read if you get a chance.  He talks about the importance and history behind those curves.

Hey Wannabe,

I would just keep a natural rocker.  If the rocker is too flat, you will have problems paddling through the winds well chop up here on the lakes.

here’s some of my boards in action at Stonie Point MN.

[img_assist|nid=1055320|title=Sean-O and Josephine|desc=|link=none|align=left|width=165|height=285]

[img_assist|nid=1055462|title=Go Deep|desc=|link=none|align=left|width=262|height=169][img_assist|nid=1055461|title=Drop Sean-O|desc=|link=none|align=left|width=281|height=181][img_assist|nid=1055458|title=Drop|desc=|link=none|align=left|width=316|height=204][img_assist|nid=1052983|title=#1|desc=|link=none|align=left|width=268|height=203][img_assist|nid=1055321|title=Sean-O shack|desc=|link=none|align=left|width=346|height=183]

The picture did not come through on my post . . I'll try again.  Let's see if it works.  I read the Huckster's post and have taken note that I need to get rid of the flat spots and incorporate a real shallow rocker in the remainder of the board.  Now that I think of it, that makes perfect sense in that the board needs to respond quickly to weight placement and rocker will be the thing that does it for ya.  That will be incorporated in the next iteration tonite . . . I'm thinking 1" total in the flat part with the deepest in the middle of the board and then subtracting 1" from each of the current nose and tail rocker sweeps.

Mahalo ya'll


You should check out the free download for Aku Shaper, It is super easy to use and it will help your design process.



A little OT, but not by much:


OK, I admit it.  I have a perverse attraction to waves in the Lakes.  I spent some years surfing the gulf coast and have even surfed a few weak burgers in Barnegat Bay during noreasters, so the idea of surfing the lakes, preferrably looking like the photos above, is something I’d love to do sometime.  I almost had the chance while visiting my college girlfriend in Chicago, but no board available.  It is penciled in on my bucket list.  Thanks for posting the pics.  Are there any go-to sources of photos of surfing on the Lakes that you would recommend?


Unsalted: The Great Lakes Experience

Probably what you are looking for…they have it on Netflix. I won’t call it great, but it isn’t bad. Entertaining to see the Ocean Pacific pros try to surf the lake in winter. I think they would have run screaming if it wasn’t their job. Great Lakes surfers are hardcore to the max in their drive to surf.

There is no way I am going to surf with the probability of running into chunks of ice. I had scars on my feet and legs from chunks of ice hitting me for a couple years after fording glacial rivers in Alaska at work…