Gravity 3 - Swell energy 1

There was a thread about the role of swell energy in riding waves a while ago - which I can’t find now but check this video (takes a while to load.)

http://www.guerrillaguru.com/vidGal/vidClip38.hal

Now what role does swell energy have in riding waves? Clearly swell energy moving under the water creates a slope which gravity pulls us down, the speed of the swell (or the rate at which surface water races up the face) combined with the surface area of the board and fins is what makes surfing possible.The only time swell energy is part of surfing is when the swell hits the bottom causing the wave to pitch and you use that shoreward pitching water in the lip to push you back down in vertical top turns.

watch out steve

roy stuart got banned from sways for that heresay

Quote:
The only time swell energy is part of surfing is when the swell hits the bottom causing the wave to pitch and you use that shoreward pitching water in the lip to push you back down in vertical top turns.

Ride 5 foot 8 second interval wind swell waves. Ride 5 foot 15 second ground swell waves. Then tell me swell energy is not part of surfing.

Everybody Surf’s Nowadays

Energy is a curious term. In the physical sciences its meaning is quite precise, when used colloquially less so.

The definition of energy in the physical sciences depends on the definition of work, which again has precise meaning in the physical sciences, but again when used colloquially less so.

The kind of energy that can be associated with an ocean wave is both kinetic and potential. Kinetic energy refers to the kind energy that is inherent in moving objects. Potential refers to the kind of energy that is a function of position. When you interact with a wave, the possibility exists for some of the kinetic energy of the water molecules to be transformed into other forms, such as your own kinetic energy. The transformation is via a force, yet another term with a precise meaning in the physical sciences, but when used colloquially less so.

In the last paragraph I used a kind of reasoning. Reasoning is also one of those curious terms. It’s often used as a synonym for logic, which it is not. For example psychotics** (see footnote below) have their own way of reasoning. Logic is about the rules governing argument and psychotics can be perfectly logical in there reasoning.

Reasoning in the physical sciences is one that has come about by consensus over time. The kind of reasoning that I applied in the third paragraph above has its roots in Newtonian mechanics. The argument is one based our modern notions of causality, of which Newtonian mechanics is very much apart.

A remarkable and wonderful part of this system of reasoning is what is often referred to as Ockham’s Razor or the law of parsimony – in a nutshell, that an explanation for unknown phenomena should first be attempted in terms of what is already known. In order to apply this rule however, one has to be clear as to what phenomenon is being addressed.

It would appear that surfing means a lot of different things to a lot of different people. In fact the term seems to have taking on a meaning far removed from its original – e.g. it is now possible to surf the Net. But if just restricted to water activities, there is wind surfing, kite surfing, river surfing, surfing simulated waves on decks of cruise ships, wake surfing, foil surfing, etc. , each claiming rights to the term.

What they are actually claiming is that there is something about surfing that seems to be embodied in the activity they are each respectively referring to, even if it’s just the shape of the board used in the activity. The problem is that all these activities do not have much more in common other than they usually involve a board and water. Or is it now the fact that if the activity involves a board and water it’s ‘surfing’?

‘Water Flow direction results’There is however one use of the term that does involve something quite unique. It is the kind of interaction that I described in craftee’s thread regarding Savistky’s planing as applied to a moving wave form. It does not rule out the possibility of making use of gravity to make rapid drops, nor dissipating acquired kinetic energy to make dramatic cutbacks, or aerials. It does however attempt to capture what separates one kind of surfing from all the rest by revealing a curious and wonderful means of propulsion.

The Val Ching video referenced in the post is an excellent illustration of this kind of propulsion. Mr Ching does not repetitively drop and climb through the gravitational field to acquire kinetic energy, he is using another means to move. Again, this is not the only way to acquire kinetic energy in the activity surfing, but it is the one that distinguishes it from all other activities currently marketed as ‘surfing’. It is always operating during surfing. The interaction governs much of the current design of surfboards, but not all.

kc


**, see virtually any of Roy Stuarts (a.k.a TomBloke) physical arguments in the Swaylocks Archives, and of course there’s Silly’s curious reasoning in his post above as to why Roy was banned.

Is there a cliff notes version of that post?

Sort of… not Cliff but just as good.

$29.95 for the downloadable version.

$39.95 for the shrink-wrapped version (not including shipping and handling.)

But then there’s the 100% discount for both visitors and registered members of Swaylock’s - anonymous or otherwise… lucky you.

Quote:

Ride 5 foot 8 second interval wind swell waves. Ride 5 foot 15 second ground swell waves. Then tell me swell energy is not part of surfing.

That’s what this bit “the rate at which surface water races up the face” is about.

I picture it like a rolling pin being moved under a blanket. The faster the swell is moving, the faster surface water is moving up the face. Therefore the amount of lift the planning surface generates increases as flow rate increases. High period windswell - more planning surface is required. Low period groundswell - less planning area is required. Tow in waves are the extreme end of this. 25 sec swells move so fast that with a standard board the lift is greater than the downward force of gravity – So the design of tow boards has evolved so planning surface is reduced and gravity is given a bit of a hand with weights in the boards. What I’m saying is swell energy is not directly imparted to the board – it creates the movement of surface water that provide lift and the slope which the board slides down due to gravity. This is a very simple view there’s also stuff going on with water flow around rails and fins. The video shows these basic principles in action.


What I’m saying is swell energy is not directly imparted to the board – it creates the movement of surface water that provide lift and the slope which the board slides down due to gravity.


My take, as a person very involved in the physical sciences:

Energy, like mass can not be created nor destroyed, however, it can be transfered from one form to another. Radiation energy from the sun hits the earth and creates weather systems, i.e. storms. When a storm creates a swell, wind transfers some of its energy to the ocean. Energy is then transfered through the ocean by a swell, with each water molecule transfering most (no energy transfer is 100% efficient) of its energy to the next.

When that energy comes to the beach you are at in the form of a swell, as the ocean floor rises the energy is transfered less laterally and more vertically (due to the boundary of the shallow ocean floor), until it gets to the point where it forms a “wave” and then breaks. When you catch a wave, you are harnessing this energy, or more so transferring it to yourself. When you paddle into a wave and displace water, the kinetic energy from the water you displaced has turned into your kinetic energy, allowing you to surf. As a surfer does turns up and down a wave it is a constant exchange of kinetic and potential energy, along with the transfer of muscle energy within the person to kinetic and/or potential energy.

The upward movement of water that you are talking about IS the swell energy. It lifts you up and in that action it transfers some of its energy into your potential energy, then when you surf down the wave, you have kinetic energy and can produce enough lift from your board to surf. Waves are swell energy, whether it be from a storm with 40 ft seas and a huge fetch or from local winds sitting off the coast with a small fetch. Surfing is the act of transfering some of this energy and using it to ride.

The best high performance surfers are the ones that can position themselves in the most powerful parts of the wave to transfer as much of the wave energy to themselves as they surf, and then use that energy to bust powerful gouges, etc.