Swell Riding

A interesting question came up with some fellow paddlers during a post work pint. Why is it that you are unable to ride ocean swells for longer then 30-100 yards? In theory that swell keeps traveling a lot further. I couldn't come up with a reasonable, good explaination. Shore break you can ride right to the beach, but ocean swells offer a limite ride, despite the fact that they will travel hundreds or thousands of miles.

Submitted by watersledder on Fri, 04/09/2010 - 2:47pm



we are too slow to keep up with the swell...


#1 Fri, 04/09/2010 - 2:52pm


I KNOW I am too slow to keep up!


#2 Fri, 04/09/2010 - 3:06pm


I realize that a good ground swell moves too fast. But this even happens on crappy wind swell that is moving slow ( 4 to 6 second period). This even happens when riding very slow moving lake chop. There must be more factors at play then wave speed.


#3 Fri, 04/09/2010 - 3:54pm


Steepness and overall form of the wave play a part in "ridability", I tink. While a wave may travel for many miles, it may not always posess the proper form and speed for riding throughout its "lifetime".


#4 Fri, 04/09/2010 - 4:07pm


I'm sure there are a lot of factors that govern how long a wave can be ridden, but it is impossible to ride a wave that isn't there. Wind generated waves (what we're talking about here) are dispersive because they are composed of different frequencies (or wavelengths) and travel at different speeds. This results in constructive and destructive interference of different frequency waves (i.e. a beat frequency, such as when tuning a guitar, or grouping of waves into sets).

So, if you're on a wave and riding along, there's a fairly definite chance the wave will encounter another wave and maybe get bigger or maybe get smaller. If it gets small enough the force balance keeping you moving with the wave is going to change enough that your canoe's drag is going to be greater than the acceleration provided by gravity pulling you down the wave face and you won't be able to keep up with the wave without paddling (adding another force to the balance). The wave could also just disappear leaving you suddenly decelerated and unable to to accelerate quickly enough to catch the wave again when the interfering wave has passed.

Wikipedia entry on dispersion in surface gravity (wind generated) waves: http://en.wikipedia.org/wiki/Dispersion_(water_waves)


#5 Fri, 04/09/2010 - 4:17pm


You missed the memo. Any deficiencies in surfing ability are supposed to blamed on the boat you're riding. For example, after the next race with surf it is acceptable to say the following, "the waves aren't lined up enough, everyone knows (insert boat model X you raced on here) doesn't like those conditions".

If you open up the bag of excuses to the waves, then everyone and their mother will have a reason why they got beat.


#6 Fri, 04/09/2010 - 4:38pm


Brilliant.

I haven't thought about blaming the Wave for my lack of speed. But it makes sense. I use to blame my lack of chines, but this is much better.


#7 Fri, 04/09/2010 - 4:42pm


Anowara, thanks that is the best explaination I have heard yet. It makes sense when you consider that every wave has a different wavelength. So waves are eventually meeting up, either doubling up or doubling down.

If only we could paddle fast enough to move with big ocean swell. We could ride for miles?!


#8 Fri, 04/09/2010 - 5:11pm


A long time ago, Rocky Higgins fished my canoe and me out of the sea during a race, and it was amazing how long and far he could milk the bumps with his Whaler. He would power on and off and glide forever it seemed saving gas. Of course having power helps, but one thing I learned was to resist taking the drop and to remain high on the bump always looking to transfer to another bump that has sucked away the energy from the one you're on.


#9 Fri, 04/09/2010 - 11:46pm


It is gravity.

You say you want to move forward, you attempt to break free with the aid of a swell, but gravity says, "I'll help you a little, for a moment, but generally stay right where you are."

Gravity wants to pull you to the bottom of the sea.

Gravity.

It's the law.


#10 Sat, 04/10/2010 - 4:22am


Since when does the 'boat' not matter ? Regardless of surfing abilities - it does matter.

Weight of boat, paddler, weight distribution and trim, balance, shape of the canoe, ama - they all have a major influence.


#11 Sat, 04/10/2010 - 7:58am


The boat matters, but not nearly as much as surfing ability. Any of the top designs raced nowadays can be surfed well if the paddler knows how to surf, and if the paddler doesn't know how to surf, it will be difficult to do so regardless of what boat he/she is paddling.


#12 Sat, 04/10/2010 - 9:26am


Yankee said:

Gravity wants to pull you to the bottom of the sea.

And thankfully buoyancy wants to keep you afloat.

The big thing to remember about catching a wave is you need to accelerate so you are traveling pretty close to the speed of the wave when it's under you. Acceleration of whatever craft you are trying to surf and its top speed are probably the two most important factors. These two quantities are affected by all of the things Eckhart mentioned and the paddling skillz Jim is mentioning.

Here's an article I found from Popular Science that lays some of this out in a little more detail:
http://www.popsci.com/adam-weiner/article/2008-10/physics-surfing-part-o...


#13 Sat, 04/10/2010 - 11:54am


Individual surfing ability and boat design are two entirely different matters.

The ability to fly an airplane and the design of the airplane are entirely different matters.

A good pilot can fly any plane better than a bad pilot.

It is a logical fallacy - I guess by association - to use that as a reason to state that
airplane design does not matter or does not matter that much for the planes' handling.

A major factor is weight of the paddler and buoyancy of the boat/wetted surface. Also weigth distribution/center of gravity.

To anyone who claims that this does not matter, I suggest to add 50 - 70 lbs weight to your boat
to get up to 230 or 240 lbs total and then go surfing again - you may just have lost a good deal of your surfing ability.


#14 Tue, 04/13/2010 - 10:59am


Back in the real old days of the Kaiwi Channel Challenge relay, where there was just one boat and one design (long), very few experience paddlers could surf them. The very few that could were very successful. Size or weight didn't matter then, but skill did. Yet, carrying an extra gallon or more of seawater inside the hull of a surfski because of a crack didn't stop it from setting a new Molokai record. The record set by this heavier ski has never been equaled or beaten by newer skis weighing half as much. Perhaps the additional weight provided by the seawater helped the ski smooth out the glide and gain more distance on each bump before connecting to another bump? Sure, a lighter canoe excelerates faster than a heavier one, but it also slows quicker (less resistance required) than a heavier one (more resistance required). So going upwind, I'll take a lighter canoe, but going downwind, I'll select the heavier one, even if I got to use more energy to get it moving.


#15 Mon, 04/12/2010 - 9:42am


I would guess that a heavier canoe may be better in some conditions.

... If it gets small enough the force balance keeping you moving with the wave is going to change enough that your canoe’s drag is going to be greater than the acceleration provided by gravity pulling you down the wave face and you won’t be able to keep up with the wave without paddling (adding another force to the balance). ....

Canoe drag matters.


#16 Tue, 04/13/2010 - 11:08am


I imagine the extra weight of the leaky surfski had less to do with it's performance than the changing balance caused by water sloshing around inside it. When it was in a trough or otherwise fairly level, it probably didn't behave all that differently, but heading down a wave the nose would be heavier, changing the balance/trim of the ski and in this case, apparently, making it surf better.

Could also be the guy paddling it was really good at reading the ocean and managed to link wave after wave and the water inside had nothing to do with it.


#17 Wed, 04/14/2010 - 5:15am


You may be right Anowara, but all I was trying to point out was the relationship of resistance and the weight of an object, which we learned about in our science class in school.

Watersledder: next time you bog down or you think you're at the end of a run, look for the smooth water and aim for it, for that's your ticket to ride.


#18 Wed, 04/14/2010 - 10:46am


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