Swaylock's Fundraiser to Measure the Effects of Flex on a Surfboard

[swaylock]

This is it! The effects of flex on a surfboard settled once and for all!

Please consider donating today to help support this important study.

**Project Summary**

Swaylock's member BenjaminThompso has offered to assemble a team of researchers at the University of California San Diego as part of his PhD thesis in stuctural engineering to research the effects of flex on a surfboard. This proposal has led to a lenthy and detailed discussion headed up by MrJ and others on how to scientifically measure the effects of flex on a surfboard. The project is read to move forward and funds need to be raised in order to purchase electronic equipment to outfit a surfboard for remote telemetry.

All findings of this research project will be made available to the public domain.

**Project Details **

Head on over here to read about the project in it's full glory. Note this is a long thread. You may want to jump to the end to learn where things are at.

**Interested in Donating?**

Please consider donating today by clicking this donate button to help fund this unique and important research project. Donations will go directly to a dedicated PayPal account set up and managed by BenjaminThomson.

 

[img_assist|nid=1047780|title=Telemetry interfacing to a legacy data aquisition system|desc=|link=none|align=none|width=640|height=480]

[img_assist|nid=1047644|title=speculative surfboard flex remote data aquisition system|desc=|link=none|align=left|width=640|height=370]

 

[MrJ]

we need $2000 to purchase the materials of this project.

Several engineers are donating their time.  Please PM me (MrJ),
pledging how much you are willing to donate in January.  State if you would like
the donation anonymous.  Otherwise donors will be thanked and listed on
the report

cheers,

Mike

[rooster]

Could we set up a fund for my study on Holiday eating, weight gain, and wave count decrease?  Sorry, Mike.  I have a hard time taking this seriously.  Someone clever can probably figure a way to quantify flex in a surfboard, but you will have great difficulty quantifying something as subjective as performance, or the  most important factor, STOKE!!!  I wonder if there are more important questions that can be answered with such an outstanding educational opportunity.  Nevertheless, Good luck Benjamin, Mr.J. and all involved.Hope yah'all have a Merry Christmas or whatever Holiday you celebrate and a Happy New Year.  Mike

[BenjaminThompso]

 

Over the next two weeks, we will be polishing up the problem
statement, objective and scope of project.  But here is the
rough idea:

**BACKGROUND
**For decades, the surfing community has built
an impressive qualitative understanding of how a surfboard interacts
with the surfer and the wave.

**PROBLEM
**A qualitative understanding of water
pressure, water flow, surfer acceleration, surfer velocity, and skin
elongation(surfboard flex) has limitations. While it is rarely disputed that
these phenomena exist, it is regularly disputed which one(s) is
dominant and it is uncertain how they interact.

**SOLUTION
**We will
quantify water pressure,
water flow, surfer acceleration, surfer velocity and skin
elongation. This information will be synchronized
with video of the surfer and the surfer will record a personal
account of the feeling he/she had in each maneuver in each wave.
Everything that is recorded will be correlated with what surfing
visually looks like and sensually feels like.

**TESTS
**-3 surfboards of
identical shape and weight, but one has standard flex, another will
be 20% stiffer, and the other 20% more flexible.
-3 surfers of
nearly identical proportion, weight, and fitness: one Pro, one
Advanced, one Average
-Various days, various wave conditions, but
all three surfers will be surfing simultaneously for a 1.5 hour
session. They will switch boards every 30 mins.
-data and video will be constantly streaming, capturing all aspects of the session

 

POSSIBLE CONCLUSIONS(in
no particular order)**
**-in
what way and how much does a board’s shape change while surfing

-how does a board’s shape-change
effect acceleration, velocity, water flow, water pressure

-how does acceleration, velocity, water flow and water pressure affect how the board changes shape

-how does a recoil rate affect acceleration, velocity, water flow, water pressure

-what is the recoil rate in various maneuver

-what is the recoil rate that
looks best (video)

-what is the recoil rate that
feels best (personal account)

-will all skill levels like the
same board or will the ideal flex be different for each surfer

-which flex was best suited for
which skill level in which wave conditions

-when a board eventually
breaks…what are the actual forces that broke the board

-do at-home-tests like Mike
Daniel’s load-deflection test or Benjamin Thompson’s resonance test
actually correlate with real surfing

-are lab tests representative of
what is going on while surfing

-what is the velocity of a
surfer and how do maneuvers affect this

-what is the velocity and
direction of water flow and how do maneuvers affect this

-is there a resonant effect that
occurs while turning. If so, how does it affect acceleration,
velocity, water flow, water pressure. Does it correlate with an
enhanced visual display or personal feeling

-is resonance different for
different skill levels

-more possible conclusions will
surely come to mind, but feel free to throw in some more!!!

[johnmellor]

Hi Benjamin -

I applaud your effort to quantitate flex. 

It would be really cool if you could get input and/or participation from someone like George Greenough.  Mitchell Rae, Steve Pendarvis, Stan Pleskunas, Bob Tinkler, etc could likely add a thing or two as well.

Seriously... why start from scratch when the above named people have done so much preliminary work? 

[BenjaminThompso]

John,

Certainly!  I don’t want to reinvent the wheel in any way.  If you know people that can contribute to this research then please encourage them to post on the thread!

I do know of some tests that have captured some of the data that we are seeking.  However, I think the value in this test lies in simultaneously recording various phenomena so that one single maneuver can be looked at from various angles.

[johnmellor]

 Post deleted.  JM

 

[swaylock]

Ben,

When you get the paypal account setup let me know – we
could then put a “ChipIn” widget at the top of the thread to track
donations.

Mike

[MrJ]

@$1

Could we set up a fund for my study on Holiday eating, weight gain, and wave count decrease?  Sorry, Mike.  I have a hard time taking this seriously.  Someone clever can probably figure a way to quantify flex in a surfboard, but you will have great difficulty quantifying something as subjective as performance, or the  most important factor, STOKE!!!  I wonder if there are more important questions that can be answered with such an outstanding educational opportunity.  Nevertheless, Good luck Benjamin, Mr.J. and all involved.Hope yah’all have a Merry Christmas or whatever Holiday you celebrate and a Happy New Year.  Mike

Rooster, well at least we have succeeded in amusing you! thats something as Swaylocks is all about fun. I don’t have a family unit that traditionally celebrates Christmas so I don’t celebrate it as such either. However I’m getting some time off work and about to head to the beach for 5 days of surfing. I’ll be back briefly and then another 5 days of surfing. I won’t have an internet connection at the beach.

Merry Christmas and a Happy new year!

Mike

[rooster]

[quote="$1"]

[quote="$1"]

Could we set up a fund for my study on Holiday eating, weight gain, and wave count decrease?  Sorry, Mike.  I have a hard time taking this seriously.  Someone clever can probably figure a way to quantify flex in a surfboard, but you will have great difficulty quantifying something as subjective as performance, or the  most important factor, STOKE!!!  I wonder if there are more important questions that can be answered with such an outstanding educational opportunity.  Nevertheless, Good luck Benjamin, Mr.J. and all involved.Hope yah'all have a Merry Christmas or whatever Holiday you celebrate and a Happy New Year.  Mike

[/quote]

Rooster, well at least we have succeeded in amusing you! thats something as Swaylocks is all about fun. I don't have a family unit that traditionally celebrates Christmas so I don't celebrate it as such either. However I'm getting some time off work and about to head to the beach for 5 days of surfing. I'll be back briefly and then another 5 days of surfing. I won't have an internet connection at the beach.

Merry Christmas and a Happy new year!

Mike

[/quote]

 

Well said, Mr. J.  Well said.  I'm off the next couple of weeks and on a mission to get as many surf days as possible.  And I apologize for being so judgmental in regards Benjamin's education.  Mike

[mtb]

@$1

 

Over the next two weeks, we will be polishing up the problem
statement, objective and scope of project.  But here is the
rough idea:

**BACKGROUND
**For decades, the surfing community has built
an impressive qualitative understanding of how a surfboard interacts
with the surfer and the wave.

**PROBLEM
**A qualitative understanding of water
pressure, water flow, surfer acceleration, surfer velocity, and skin
elongation(surfboard flex) has limitations. While it is rarely disputed that
these phenomena exist, it is regularly disputed which one(s) is
dominant and it is uncertain how they interact.

**SOLUTION
**We will
quantify water pressure,
water flow, surfer acceleration, surfer velocity and skin
elongation. This information will be synchronized
with video of the surfer and the surfer will record a personal
account of the feeling he/she had in each maneuver in each wave.
Everything that is recorded will be correlated with what surfing
visually looks like and sensually feels like.

Could you please explain to me how you plan to measure water pressure (=force/unit wetted area) and (of special personal interest) water flow?

(Also as a minor quibble, it would seem to me that you’re measuring board acceleration, and deriving board velocity from that, and not directly measuring/calculating surfer accelerations/velocities.)

@$1

**TESTS
**-3 surfboards of
identical shape and weight, but one has standard flex, another will
be 20% stiffer, and the other 20% more flexible.
-3 surfers of
nearly identical proportion, weight, and fitness: one Pro, one
Advanced, one Average
-Various days, various wave conditions, but
all three surfers will be surfing simultaneously for a 1.5 hour
session. They will switch boards every 30 mins.
-data and video will be constantly streaming, capturing all aspects of the session

 

POSSIBLE CONCLUSIONS(in
no particular order)…(snipped)…

 

It would be nice if you would also include an overview as to the method(s) of data analysis that you propose to use.

On another aspect:

I’m confused (and too lazy to search through the pair of long threads) as to whether or not you’re still planning on leaving the Atomic IMU modules powered up until the battery runs out of power? Unfortunately the data sheet for this module doesn’t seem to specify the power drain in all possible operational states (i.e. off, “idle”, operational). Obviously no power is drawn when the unit is “off”, and I assume that the 24 ma specified in the data sheet is the power drain in the “naked” operational state without being used in combination with XBee, and increasing to 74 ma if used in combination with an XBee.

Those operational state numbers don’t seem very promising for measurements spread out over the course of a year. Since the battery stores 1100 ma-hr of power, that means that the sensor module used in combination with XBee would only have a life-time of (1100 / 74) = 14.9 hours. Assuming (as in your postings) that each “experiment” would last 3 hours (each surfer surfs two 1.5 hr long tests during an experiment), that means that you’d get data for about 5 experiments before the batteriy died. Furthermore, that’s the maximum number of 3 hour duration experiments only if the modules could be turned off between experiments.

If the modules were left on (perhaps in the “idle” state?) continuously, the number of experiments would obviously be less. Presumably the modules would be maintained in the “idle” mode to reduce the current drain. But unfortunately, the data sheet for the sensor module does not appear to list the current drawn in this “idling” state (w or w/o the XBee module) so it’s not possible to predict battery life for various ON/OFF scenarios.

Anyhow…it would certainly appear to me that an external ON / OFF switch would be desirable to maximize the number of experimental runs that can be executed before the battery dies, provide much more flexibility in when each experiment can be executed, and to allow one to execute power ON/OFF resets.

A suitable, inexpensive, waterproof switch for this application could be an adaptation of the magnet-activated intrusion alarm switches of the type commonly used on doors, windows, etc. 

mtb

 

[BenjaminThompso]

@$1

Could you please explain to me how you plan to measure water pressure (=force/unit wetted area) and (of special personal interest) water flow?

(Also as a minor quibble, it would seem to me that you’re measuring board acceleration, and deriving board velocity from that, and not directly measuring/calculating surfer accelerations/velocities.)

measuring pressure…we’re currently looking for a packaged solution.  If none come up, we will calibrate strain guages to measure pressure.  One option may be to have 1/4" holes in the foam, place a membrane with a strain gauge over the hole, then glass it.  This strain gauge (for pressure measurement) should be placed adjacent to a strain gauge (for strain).  When pressure is applied the membrane, it will deflect because there is no foam under it.  The deflection of the membrane will create strain in addition or subtraction from the strain due to surfboard bending or torsion.  The difference in strain between the adjacent strain gauges (one for pressure, the other for strain), will tell us how much pressure is being applied to the skin at that location.  A similar method is often used when people want to compensate for temperature changes.

measuring flow…I think I am going to have the undergrads build this…it seems straight forward.  I’m thinking of having the glasser install a FCS plug on the stringer maybe a few inches in front of the front fins.  The flow vane will snap into the FCS plug, will have propellers that measure velocity and they will be on a pin that can rotate in any direction to measure flow direction.  Yes, flow direction changes throughout the board, but this seems like the most neutral spot.  If you can recommend a better location, I am all ears.

@$1

(Also as a minor quibble, it would seem to me that you’re measuring board acceleration, and deriving board velocity from that, and not directly measuring/calculating surfer accelerations/velocities.)

Yes, we are measuring surfboard accel, veloc, and displ.

@$1

It would be nice if you would also include an overview as to the method(s) of data analysis that you propose to use.

We will eventually.  Everything will be transparent.  In fact, we’ll make it clear enough so that anyone can duplicate our test procedure…given they have $2000 and a few hundred hours to spend.

@$1

Those operational state numbers don’t seem very promising for measurements spread out over the course of a year. Since the battery stores 1100 ma-hr of power, that means that the sensor module used in combination with XBee would only have a life-time of (1100 / 74) = 14.9 hours. Assuming (as in your postings) that each “experiment” would last 3 hours (each surfer surfs two 1.5 hr long tests during an experiment), that means that you’d get data for about 5 experiments before the batteriy died.

The batteries and radios will be the only things outboard to maximize radio transmission and so we don’t have to worry about changing a battery.  Battery and radio together are smaller than a small cellphone.  It will sit on the nose of the board.

[wouter]

hey guys

i am in for some money, how about updating the money meter?

i  love this project, have yet to read its description fully

surferdave are you in too?

mook?

ciao!

[karl]

Hey Mike and Benjamin

I'm keen to help out with $ - don't have any expertise to contribute.

Have you thought about if and how the data and analysis will be made available and to whom? Will some or all be available to anyone, or more to contributors, will the data and analysis be treated separately etc?

You may or may not have thought about this, but I think it would be good to be clear about what people are supporting from the start (you can see it getting political).

To get things going, I think the raw data should be available to anyone (few are likely to know what to do with it), and a basic analysis presented on Sways to further the debate about flex. There will be a cost in time to whoever is going to analyse the data, which may limit how far any analysis goes.

To my mind increasing knowledge is a valuable thing to do for its own sake. I'm not sure there would be any commercial value in the analysis because I suspect we'll just end up with more questions than answers.

What do you think?

Karl

[privateer]

In the end there will be no empirical evidence just another analogy
based on a hypothesis that will yield no real direction in the craft of
board building.There are so many great shapers world wide that look
have looked for those answers and have chosen their given paths.To
believe that a group of scientists will give some empirical evidence is
to discount the greatness of some of the best shapers in the world and
their years of mowing foam .On any given day there are so many different
types of boards in the water and each surfer feels his own merits ,kelly
slater will not be the next dick brewer but he will have a following the computer will never replace the hands ,when artificial intell merges with the machine some new possiblities come into existence when that finally happens you will no longer really ride a wave but merrily put on your nueron  inducing helmet and surf the best waves in the world alone? then back to your cubicle the sad part is that possiblity is becoming more of a reality than you could ever imagine long live the difference the attempt of one board can not happen.Freedom from the manchine!!! Just the other side Aloha…

[BenjaminThompso]

@$1

I’m keen to help out with $ - don’t have any expertise to contribute.

I’ll setup up a paypal account soon.  Thanks!

@$1

Have you thought about if and how the data and analysis will be made available and to whom? Will some or all be available to anyone, or more to contributors, will the data and analysis be treated separately etc?

You may or may not have thought about this, but I think it would be good to be clear about what people are supporting from the start (you can see it getting political).

To get things going, I think the raw data should be available to anyone (few are likely to know what to do with it), and a basic analysis presented on Sways to further the debate about flex. There will be a cost in time to whoever is going to analyze the data, which may limit how far any analysis goes.

To my mind increasing knowledge is a valuable thing to do for its own sake. I’m not sure there would be any commercial value in the analysis because I suspect we’ll just end up with more questions than answers.

What do you think?

The bulk of the project will just be collecting data, cleaning it, and making it friendly for public consumption.  The data collected will be fully released in June 2010.  Preliminary data will also be released starting in March 2010 when the testing begins.  A report will also be published in June.  It will factually state how a board flexes in certain maneuvers in certain wave conditions, water pressure distributions, water velocity and water flow direction, among other things.  Explaining why these phenomena occur(modeling and theory) will not be provided.  General findings will be addressed in the report.  We will provide one in depth analysis, of one maneuver over a two second frame, so that the public can see how a data analysis can be conducted.  We will provide calculations in an Excel spreadsheet because people are familiar with this software.  Therefore, it should then be easy for them to do their own analysis…choose any 2 second frame of data and plug it into the spreadsheet.  There will be thousands of data frames.  Anyone can watch the videos, find a maneuver they are interested in, download the 2 second data frame, and plug it into the spreadsheet or conduct their own analysis.

[MrJ]

@$1

@$1

…

Rooster, well at least we have succeeded in amusing you! thats something as Swaylocks is all about fun. I don’t have a family unit that traditionally celebrates Christmas so I don’t celebrate it as such either. However I’m getting some time off work and about to head to the beach for 5 days of surfing. I’ll be back briefly and then another 5 days of surfing. I won’t have an internet connection at the beach.

Merry Christmas and a Happy new year!

Mike

Well said, Mr. J.  Well said.  I’m off the next couple of weeks and on a mission to get as many surf days as possible.  And I apologize for being so judgmental in regards Benjamin’s education.  Mike

cheers Rooster, I am having to make a leap of faith when it comes to flex, I have no expert knowledge on this subject, however flex is the subject Benjamin specialises in so I’m prepared to make that leap of faith regarding what the strain gauges (flex sensors) can tell us.

However when it comes to the embedded system needed to transmit this data in real time then thats a subject I have some background in (I’m a software engineer who specialises in datacomms). Although I have no hands on experience with this particular type of unit and data transport it is my opinion that it is achievable with readily available mail order equipment and it is not pie in the sky technology. However Benjamin’s mate David is an expert in remote sensing and has actual hands on experience with the proposed data transport equipment (ZigBee/XBee wireless) so I think the project is in good hands.

My holiday at the beach went well and I managed to pace myself and avoid wearing myself out on the first day. Picture of my accomodation below and a sample of the conditions (approx 4’ everyday).

I had a really good wave yesterday evening, whacked the lip and felt the board shudder, I would like to know what the flex sensors would tell us on a move like that.

I hope you are getting some good waves. I’ll be going back for more in a few days.

cheers,

Mike

[img_assist|nid=1048033|title=christmas holidays in Australia|desc=|link=none|align=left|width=640|height=480]

[img_assist|nid=1048034|title=summer beachbreak|desc=|link=none|align=left|width=640|height=480]

[MrJ]

@$1

…

I’m confused (and too lazy to search through the pair of long threads) as to whether or not you’re still planning on leaving the Atomic IMU modules powered up until the battery runs out of power? …

Mtb, that suggestion and a lot of the diagrams was just me enjoying myself working my way through the technology and speculating with no hands on experience with this stuff. Now that Dr Mascarenas is working on it, I’m just happy to sit back and watch.

[MrJ]

Claude, thanks for your PM. I tried to reply, but the message board says you do not accept PMs so I am letting you know that I have passed on your board design question and interests to Benjamin.

[BenjaminThompso]

Reply to Claude:

The surfboards will be CNC machined, so that they will be identical.  We will post the CNC file for anyone to look at or use.  It will be a very standard performance shape…probably 6’0" x 18.5" x 2.25".

Test sites will probably be at:

BLACKS, good video visibility, long groundswell lefts from mushy to dredging, all year
SWAMIS, good video visibilty, long groundswell rights from mushy to steep, mostly winter
SCRIPPS, good video visibility, plenty of windswell rights and lefts, springtime

Testing will be time stamped, so that anyone can look at the tide, wind, and spectral buoy data for the hour of testing.
http://lajollasurf.org/torreypines.html
http://lajollasurf.org/missionbay.html
http://lajollasurf.org/sanelijo.html
That info is live, but historical data is kept on http://www.ndbc.noaa.gov/.