Rocker

Does anyone know how rocker is determined in canoes. From what point to what point do you measure?



Rock On!

Rocker
Per Barton’s article, rocker is the amount of curvature along the keel of a boat under the waterline.

The real trick is … just where do you


start or stop in measuring rocker? At which point in the curve from keel (horizontal bottom of the boat to stem (vertical ends of the boat) do you pick? ;^)



I know where I pick. From reverse engineering I know where most designers pick. A big problem here is the sales people can easily abandon the design stated rocker and pick whatever point that gives them the rocker they wish to project. Luckily most do not , but still enough do that it is confusing.



The point I pick is where the hull has been following a pretty consistent horizontal line and then suddenly makes a break, heads up, normally before or just as it makes the sharper turn to the vertical line. This is a judgement type call though and is not necessarily uniformly applied. Kind of like a rule guided by a feeling.



Now that you have that all figured out … How do you determine asymmetrical rocker? ;^)


:^)



Mick

Rocker?
Do you mean Springsteen?



“I’m a rocker, baby, I’m a rocker, every day”

Yes Vic
but are you a 1 1/2 inch rocker or a 2 1/2 inch rocker.

Canoe Rocker
I went back and read the Barton string. So I take it that there is no sort of standardized measurement for rocker. I also got the notion that you gotta paddle the beast and paddle in a number of conditions before you know whether you’re compatible and can spend the rest of your life together. I’m checking out a Prospecter hull for three days next week (NovaCraft) on a river, but I usually avoid rivers if I can while tripping - so I guess I’ll just have to conisder the time spent with Ms Prospector as a date.

That all depends
If we’re taking about my canoe, Mad River says 2.25 inches rocker



If you ask my wife, I’m ready for the rocking chair rocker

Use a laser level to determine rocker
A simple way to determine rocker, both fore and aft, is to buy one of the little bullet laser levels that has a built in bubble level. I bought one on sale for $10. Place the canoe upside down on sawhorses, put the bullet laser level at the middle of the hull and move the hull back and forth till the bubble level shows level. Then project the laser Beam fore and aft and side to side.



Where the laser level is sitting measure from the beam to the hull to determine how high the beam is off the canoe. Mine is two inches. Then add that measurement to 4 inchs which is your 4 inch water line. In my case my 4-inch waterline is located 6-inches below the laser beam. You can mark it all the way around the boat with a Sharpie or Magic Marker. Or, you can lay out the 4-inch waterline all around your boat with painters tape, then spray paint a solid line at that location so you can see at a glance if your hull is properly trimmed on the water.



Once you know where the 4 inch water line is then you can follow manufacturer or designer directions for measuring the rocker. For example, one well known designer measures rocker on his boats at a point 12 inches back from where the 4-inch waterline meats the stem. Other manufacturers and designers may use a different method.



But as long as you know what their method is, and where your 4-inch waterline is, then you can determine rocker on that company’s hulls.



It would be very useful if the canoe manufacturers would agree on a particular method, then we could compare canoes more easily.