Hi ppl

Is a stopper the same as a hole just a different name ?


Whats the easiest way to tell the differnce between a stopper and a wave just by looking at it? Sometimes i see waves and think its a stopper.

Cheers ppl

Merry Christmas to you all

Jayson

By definion the stopper can be either a breaking wave or a hole. Both can stop your dowstream momentum. There's no definate point where you can call a feature hole or a breaking wave - you have to consider the volume and angle of the inflow, the length and the volume of the recirculation and the height of the foam pile.

Experiment with different waves and holes and notice how they change with different water levels.

A Stopper- is any hole or wave that stops your downstream momentum.

A Hole- (also called a hydraulic) is a recirculating feature caused by water passing over an obstacle, creating a recirculating upstream flow. NOTE: The diffrence between a hole and a breaking wave is that a hole recirculates water both upstream AND downstream, unlike a breaking wave. Breaking Waves recirculate water upstream but there is no downstream re-cycle.

Saddle-UP,
Whitewaterules

Whitewaterules wrote:

A Stopper- is any hole or wave that stops your downstream momentum.

A Hole- (also called a hydraulic) is a recirculating feature caused by water passing over an obstacle, creating a recirculating upstream flow. NOTE: The diffrence between a hole and a breaking wave is that a hole recirculates water both upstream AND downstream, unlike a breaking wave. Breaking Waves recirculate water upstream but there is no downstream re-cycle.

i'm afraid i'm not following you here. pardon my ignorance

Technically speaking the difference between them is the variation and value of a number called the Froude number (Fr). In engineering terms any hole/stopper/wave is called hydraulic jump. Do a Google search on it if you really want to know the difference

I'm sure most people don't give a rats ass though

Does sound a bit complex!

In the UK holes are called stoppers, and stoppers are called holes. We also call some holes pourovers (I don't recomend going in those to play).

In the US They have even more names for them depending on where you live included (but not limited to): Hole, Stopper, Pourover, Hydraulic, Keeper & Maytag.

They are all pretty much the same thing although as I said I tend to distingish between holes and pourovers, coz pourovers are nasty!

Jeroen wrote:

Whitewaterules wrote:

A Stopper- is any hole or wave that stops your downstream momentum.

A Hole- (also called a hydraulic) is a recirculating feature caused by water passing over an obstacle, creating a recirculating upstream flow. NOTE: The diffrence between a hole and a breaking wave is that a hole recirculates water both upstream AND downstream, unlike a breaking wave. Breaking Waves recirculate water upstream but there is no downstream re-cycle.

i'm afraid i'm not following you here. pardon my ignorance

Okay so let me try to explain myself again. Please be advised that this is how the terminology as used in the US, which may vary elsewhere.

Engeneering terms may vary from kayaking terms also, but here is my further explination in kayaking terms.

If you look at a wave with a foam pile, there is whitewater falling down the wave-face and upstream. The whitewater is pushing primarily upstream (against the current). Then the force of the whitewater dissapates, in various non-uniform vectors. In a hole, the whitewater stays uniform, similar to a circle or elipse. The whitewater goes upstream AND circles around back downstream, returning with the current. The whitewater circulates in a more uniform and cohesive manner. So... a wave is whitewater going upstream and disapating and a hole is whitewater going in a cyclical cycle (round and round).

A Stopper- is described as a hole or a wave who's exerted upstream force is equal or greater than the momentum of a mass traveling downstream (that's the best I can describe it in my own words).

Bah,

It's no rocket science.

Have fun - either in a hole or wave. Know the difference bwtween a fun and scary feature.

Merry xmas,

Tuomas

AdrianTregoning wrote:

Technically speaking the difference between them is the variation and value of a number called the Froude number (Fr). In engineering terms any hole/stopper/wave is called hydraulic jump. Do a Google search on it if you really want to know the difference

I'm sure most people don't give a rats ass though

This is cool. Now I know yet another thing that I myself think is incredibly interesting, and will almost certainly explain it to someone who will resent me for it.

This looks like a nice page, where you can actually calculate what will happen in some concrete situation (you have to register at their site to use the calculator):

www.lmnoeng.com/Channels/HydraulicJump.htm