Basic Physics of Surfing -

General Discussion
1

Ok this is due to the discussion goin on over in the The role of buoyancy during paddle-in take-offs.

i think as a whole we can come up with a list of basic principles governing surfing, as we all word things differently i would expect to see some disagreements but this is where we can do it. once a majority has agreed upon a certain concept i think it should be kept in the resource section for noobs and when alzeimers begins to set in for the rest of us and we forget what we agreed on :wink:

Lets start with basic stuff, things we all ā€œcommonsenseā€ wise would agree with e.g. more floatation(volume) wether by thickness or length in a board will increase the possibility of catching a ā€œrolling/softā€ wave etc.

if we can clarify basic principles governing surfing i think it will help eliminate false myths, create a more accepted universal understanding of surfing physics and also help our surfboard design.

i am in no means trying to ā€œkeyholeā€ anyones ideas, and keep anyone from coming up with radical ideas, just merely trying to clarify basic principles for the better understanding of everyone including me.

you all get where im coming from?

any suggestions

2

Float is goodā€¦except when duck diving.

3

Before you can talk about the ā€œBasic Physics of Surfingā€ you have to understand and agree upon the ā€œBasic Physics of Breaking Ocean Wavesā€.

For the most part, the water (micro) is moving up, and the wave (macro) is moving forward.

You might want to look at these threads:

http://www.swaylocks.com/forum/gforum.cgi?do=post_view_flat;post=374269

http://www.swaylocks.com/forum/gforum.cgi?do=post_view_flat;post=277120

4

Thanks obproud,

I think i have gone the wrong way with regards to the title, please ignore the physics part. :wink:

i was hoping to try and keep the idea behind this simple and not to complex, coming up with statements that we know to hold true in regards to surfing from a personal view rather than scientific.

although there is alot of info within in this site, it can get very tech for someone who wants to know if changing to a flatter rocker rather than adding volume will get him into the wave earlier.

alot of things influence surfing, we all know that much. but what can we say about the basics, the need to know sorta stuff before you find yourself amongst the super tech.

surely people have ideas about things they have found during a session?

could one guideline be this statement:

Generally, the flatter the rocker the earlier it will begin to plane along a wave?

would this be accepted by the sways community as true, or does this need some work?

i think a guide with statements like this would be great, it would help define a what sort of board to build and what type of waves its aimed at. as well as create a consensus

i know alot of you would consider this just a given but some people are really confused bout this sort of stuff, its all hear say untill we can all put up our hand and say ā€œthis is how it isā€ like a rule book kinda.

for instance if i was new to surfing and came to sways, saw this guideline of sorts it would help me understand the fundementals of what sort of board i need for the waves i want to ride.

does any one have any statements they could make? who cares if its not quite right, or are worried bout looking like a fool, lets just see what happens. no one will give you s##t. we are all trying learn of each other, thats why we signed up.

Heres another one,

The longer the board the earlier it starts to plane along a wave?

what do you think?

or another

more rocker helps with steeper/ledgier the waves?

5

I think there are so few hard and fast rules in board design that itā€™s very difficult to talk in absolutes. There are too many confounding variables to say, ā€œflatter is easier to paddle,ā€ when board length, thickness, what kind of rocker, etc. all influence the ability to paddle.

Maybe you could start by talking about the basic laws of physics that apply to boardsā€¦ like, displacement, buoyant force, liftā€¦ stuff like that. Then people can ask what principles of physics can be applied to board design, rather than try to go backwards and ask, what elements of board design can be explained by physics.

6

Moonfish -

All other things being equal:

More rocker = harder to paddle + later entry into waves

Shorter = harder to paddle + later entry into waves

Wider = Easier to paddle (up to a point) and easier to catch waves,

Thicker = Easier to paddle and maybe a little easier to catch waves (but lots of disagreement here - some claiming that thereā€™s no wavecatching benefit to thickness or even that it has disbenefits! - Maybe thereā€™s an ideal thickness???)

7

Excellent answer, the rest is in the archives.

8

No offense intended Shannon - But, you may find some good long threads in the archives, as Iā€™ve participated in a couple of multi-page discussions on this type of thing in the past.

In my nut shell - pressure differences.

9

No, none taken taylor.

And thanks for your replys guys,

your prob right NJ, should go that way, be interested to see in it stays basic tho! :wink:

cheers

10

Moonfish, I like the re-occurring design threads, theres always someone with a new angle and its a bit of fun to read each persons take of the same forces.

Theres a few thread that make a comeback every year or so and the physics of surfing is a good common ground thread as we all try to understand and use our own experiences to form into a sensible Physics of the Wave Theory.

As for a rule or a concept, Id offer that ā€˜Rocker can be replaced with outline.ā€™ That is if you keep the nose rocker flat you can loosed it up by pulling the outline inā€¦

11

Is it a general assumption that a longer board paddles faster than a shorter board, or has it been proven ? anyone know.

If you put the same volume into the shorter board with the appropriate rocker as the longboard is it proven that it will be slower to paddle?

Riding a Mccoy Nugger for the past few months makes me suspicious of ā€œgenerally acceptedā€ principles.

12

Yep - itā€™s been proven burnsie -

where v = max velocity in knots and LWL is the length of waterline in feet

13

Hi,

I live in Brazil, and our waves are weaker than most places (even beachbreaks) around the world, thanks to a 200 miles marine platform along our coastline. Being so, as a shaper I strugled all my life to minimize this problem while catching waves. After more than 25 years, I conclude that physics is just a part of the game. The human factor plays more than we can generally suppose. Factors as fitness, paddle timing, wave selection (with a perception of anticipation) are more important than any shaping design.

I know several exemples of very fit guys/girls who ride on really good boards (shortboarders and longboarders), but that have a strong problem of paddle timing and have a hard time to catch waves (soft or hollow). On the other hand, I know guys/girls who are not so fit, but can paddle easily and have a sense of timing that allowd them to catch any kind of wave.

In relation to the board volume, thereā€™s some psychological factor that have to be explained in any sense. Otherwise, who can explain the preference of some surfers on using some weird combinations, as big guys/thin boards or skinny guys/fat bords.

These assumptions are just based on my observations and experience. I know itā€™s a very intriguing and challenging matter and I donā€™t want to put the final dot on this discussion. I know human race has developed science in order to keep nature close to its understanding, but sometimes science fails in answering our questions.

Now, let me read the other postsā€¦

14

The numer one basic Physic

of surfing-when you go over

the falls and land on your butt side.

when you fall off you should swim.

easy nummber two.

pearl diving is numb err

three,the only access to pearls of wisdom.

three are enough ,for basics.

ā€¦ambroseā€¦

15

Yes I am aware of the formula as it applies to boats. But I have my doubts when it is applied to surfboards. My 5ā€™10" quad paddles a whole lot better than my 6ā€™6" sunova shortboard. Both perimiter railed balsa skin boards.

16

Burnsie - length is not the only facilitator of paddle speed - but All other things being equal - a longer board will out paddle a shorter one. -The general principle I alluded to in my earlier post seems to apply to swimming - check out http://web.mac.com/htoussaint/SwimSite/Blog/Entries/2008/3/31_Interview:_What_are_the_performance_limits_in_swimming.html

My guess would be that your quad has more buoyancy than your sunova? How much float youā€™ve got definitely affects paddling speed.

Anyway - you seem to have more boards than anyone else so why not pick a stretch of water on a flat day and count the number of paddles it takes you to get from one place to the other with different boards - I for one would be interested in the results!

Cheers

17

Cheers I will do Silverback. Incidentally that theory of longer bodies travelling faster in swimming is the reason I have rotator cuff problems. Trying to swim like that is much harder on the body.

18

Wait a minute,

Paddling from one point to another is completly different from paddling to catch waves. Longboarders catch waves first, but they start paddling earlier and some distance behind the peak in relation to shortboarders. In a paddling race between a longboarder and a shortboarder, the second one will start ahead, but after some strokes, the longboarder will pass ahead. Why? Inertia is the answer! After some time of movement, the heavier object accumulates more inertia than the lighter one. I donā€™t know if Iā€™m using the correct language to explain my point of view (help me scientists), but you can notice this phenomena easily if you make both paddlers stop stroking at the same time. Whoā€™ll be the last one to stop floating ahead?

19

hi jeff,

i can see where you are coming from, but i think its not quite right. for instance if inertia was the answer, then simply adding weight to the shortboard to make it as heavy as the longboard would then cause it to be fast.

i think its more due to the area of a larger board and floatation causing the object to have far less drag and more planing area, inertia plays the part when you just start paddling due to its weight to get goin and then glides futher once paddling has ceased.

20

Hey SF

long time no talk huh :slight_smile:

these threads are fun they are really good for expressing ideas to the masses, and you learn a crap load too!