Why Box tail?

[JC50]

I've long maintained that you can't beat skinny. My notes are somewhere on this damned computer. I did some calculations using third hand formulas from some canoe testing that showed the curve of speed from decreasing weight is never intersected by the curve of performance by increasing muscle (in the bounds of what is practical for a human). Pretty much obvious to anyone that has seen Connor Baxter kick Chuck Patterson's butt in flat water where there is NO glide. Chuck could carry Connor around like a bag of groceries. A small bag.

Don't have to go far for data; check out Road Cycling. It's all about power-to-weight and the race goes to who's smallest and strongest. Ever seen the champion hill climbers? If they grow sick of cycling there's always horse jockying...

And Enzo might say that in 1959, but these days it's all about aero. The most important thing that any formula one team can do to move up in results is hire Adrian Newey.

Somewhere I heard many years ago the highest paid members of an F1 support crew are aerodynamicists (sp?). Degree of combustion engine improvements pale in contrast to slight decrease of wind friction...but we aren't paddling at 200+ mph...

[balance_fit]

I've long maintained that you can't beat skinny. My notes are somewhere on this damned computer. I did some calculations using third hand formulas from some canoe testing that showed the curve of speed from decreasing weight is never intersected by the curve of performance by increasing muscle (in the bounds of what is practical for a human). Pretty much obvious to anyone that has seen Connor Baxter kick Chuck Patterson's butt in flat water where there is NO glide.

Ponobill
This is one point I've always debated with my peers...in the last year I've lost a lot of blubber following several programs. The performance increment, under same 'training' has been prodigious to say the least.
Will appreciate any technical evidence, such as the graphs you mention, to further strenghten my resolve to keep losing weight.
Be well !

[PonoBill]

I haven't found my work, but I did find the email from Dave that started me down the path. It's a forward from a friend of his who is on the Live Strong team:


Hmmm. I guess I shouldn't have had that piece of cake for dessert.

On Mar 9, 2010, at 1:07 PM, David Kalama wrote:

Here's that info I told you about.

Aloha,

Dave



I found a rowing study where they used a physics ratio of “the percentage loss of speed is one sixth the percentage increase in mass.” From that I compared Molokai Times between Livestrong and Shell and found an interesting correlation...

Using a 95kg boat (paddler plus boat) they determined that for every 5kg of additional weight they added 31.68 seconds per hour to their time.

Assuming a race where the only difference between teams was the weight of the combined crew members: Livestrong a 532kg crew (6@195lbs) vs Shell Va'a a 477kg crew (6@175lbs) has a difference of 55kg.

Adapting for the difference in weight ratio 55kg/5kg= 11 * 31.68seconds per hour= 348.48seconds per hour or 5.8mins/hour loss in time. So based on crew weight alone Livestrong would be losing 5.8mins/hr raced.

Over a 4.66 hour race the heavier crew would have a slower time of: 5.8mins/hr * 4.66hours= 27.028mins

2009 Molokai Hoe result
Shell vaa 4hr 40min (4.66hr)
Livestrong 5hr 8min (28mins behind)


Heres the link to the physics behind the study.
or
http://www.atm.ox.ac.uk/rowing/physics/weight.html#section7

Heres the link to the 95kg boat study.
or
http://www.fennkayaks.co.nz/weight.htm

[rkdjones]

Interesting weight-speed studies.  It makes sense to me that in displacement mode, below hull speed this sort of relationship between weight and speed is reasonable.  I think those 2 assumptions might be very important.  I still think that paddlers might be bumping up against hull speed with every stroke and that trumps everything else.  And as soon as one gets the board up on a plane, the rules for displacement hulls goes out the window.  Does a 5% increase in weight significantly affect how easily it is to get the board planing on a wave?  Robert

[balance_fit]

This info is...priceless ! Quite a bit of reading for tonight...just by scrolling through the page related to the physics of rowing, several ideas start to assault the mind:
*There will soon be a great need to standardize this measurements for the unique standing position of the sup-er, as the possibility of olympic inclusion increases.
*Flatwater or ergonometer testing will have to be armonized with creative ways of measurement of the variables in conditions that include upwind, downwind, etc.
*Caloric expenditure for sup needs to be determined for it's inclusion as resource for weight loss programs.
*a one design board may need to be developed to eliminate variability in results due to differences in outline, volume, etc. I take my hat off to the excellent job done by the designers of the comparative tests which are currently being developed.
Isn't sup wonderful !

Many, many thanks for the info,

Be well

JD

[1paddle2paddle]

SoCalSupper:  there is no way to definitively answer that question unless the conditions are defined and the ability of the paddler understood.  The optimal downwind board for me is different than the optimal flat water board.  In my opinion the biggest mistake made by paddlers (surfski & sup) is paddling a ski or board that is too unstable.  If you are constantly checking then you are not applying you max power to moving the board forward.  Similarly checking not only tires ones core (and therefore reduces the effectiveness of the rest on one's muscles) but it also wreaks havoc on one's mental state.

This is borne out by my personal results on a surfski... I am MUCH faster an a stable (ie slow ski) than I am on the state of the art elite skis because on the stable ski I can paddle absolutely as hard as I can for as long as I can last.  On the tippy ski I start out fast but once I get a bit tired or the conditions get gnarly I spend all my time checking and my overall average speed goes way way down.

While off topic, I also believe the obsession with the weight of SUPs and skis is also grossly misplaced.  While there are clearly second order effects that show lighter board/ski weight is better, the OVERALL weight of the board-paddler combo is much more important than the weight of the board alone.  This pretty easy to see if one considers the physics of the movement.  The engine needs to power the whole system (board + rider) and the wetted area (and therefore drag) are a function of the total weight... not just that of the board.  To be honest I believe (and call bs on me if you think I am wrong), I think the true effect of a "light" board is in one's mind!  In the end is is much more cost effective and beneficial to one's race results to lose 10lbs of fat than it is to buy a board that is 10lb lighter!

When my surfski buddies talk about getting the new 23lb surfski but I see an extra 10 lbs of blubber around their middle, I know who will be in front )

So enough of my digressions and theoretical fluid dynamic discussions... please don't get me started on paddle design )  Lets get back to talking about Maliko runs and why that skinny kid Conner Baxter is sooo damn fast!!

...Roger

Roger, my first question is if the weight of the craft isn't that important, why do Oscar and the other Epic guys race a 16 pound $6000 ski in the Molokai?  Also, Oscar has opined that there is a difference between weight in your belly and weight in your boat - the weight of the boat is static and cannot be finessed with body english, bending the knees, etc. 

While I absolutely agree that losing the extra 10 pounds many of us carry would be a wise and logical choice (if it were only as easy as saying it), the liveliness of a light board compared to a heavy boat is noticeable and makes a difference.  Is it worth $1000 to shed 8-9 pounds?  That I don't know, it would depend on each person's circumstances.  For Starboard boards, I've noticed that there is a big price difference for a fairly tiny weight differential.  I think then the decision is easy, save your money.

[PonoBill]

Interesting weight-speed studies.  It makes sense to me that in displacement mode, below hull speed this sort of relationship between weight and speed is reasonable.  I think those 2 assumptions might be very important.  I still think that paddlers might be bumping up against hull speed with every stroke and that trumps everything else.  And as soon as one gets the board up on a plane, the rules for displacement hulls goes out the window.  Does a 5% increase in weight significantly affect how easily it is to get the board planing on a wave?  Robert

I'm certain that paddlers bump up against hull speed, but remember that hull speed isn't a wall, it's just a VERY steep hill. and boards are constantly accelerating and decelerating--they NEVER glide. So the speed of a board is the average of it's instantaneous speeds. I think fast, light people with good conditioning keep their board at or close to hull speed most of the time. If race times and distances can be trusted (I doubt they can) the elite race paddlers are running a little over hull speed for most races.

One more reason for me to get some data with my speedometer.

[SoCalSupper]

good lord whats it take to get a straight answer around here!?

[rpmooreii]

1paddle2paddle:  Thanks for your comments.

At the limit (guys like the Chulupsky bros), the lighter board/ski will be better and probably does make a small difference over long periods of time (4 hrs plus) but I submit that for the vast majority of us the weight of the board (within reason) has little to no bearing on our speed or results.  In addition, the manufacturers make MUCH more $ margin on the expensive, super high end board so, of course, all the sponsored riders will have them... and that drives the mere mortals (esp. the ones with hefty pocketbooks) ante up the extra dough for the super light board/ski.

In addition, in some conditions a heavier board will actually be BETTER (theoretically at least) than an ultralight because of momentum effects.  For my money I never buy the light carbon skis/boards as I know it will not make a difference in MY performance.  Your results may vary esp. if your "think" the lighter board is faster.  The mental edge from such a board is likely to have a bigger effect than that of the weight.  A bit ironic but true.

Lastly, I am not dodging the questions of which design is "better" but the unfortunate truth (in my opinion at least) is that there is an optimum design for every set of conditions... which not only vary day-to-day, and hour-by-hour, but is some cases swell-by-swell.  The "best" design is simply a compromise for the anticipated conditions over an entire race but again I am a firm believer that the best paddler (combo of technique, fitness, stability, mental) wins regardless of the board design as long as he/she is not riding something was designed for completely different conditions (ie downwind board in glass conditions).  So wide tail vs. pintail (within the limits we are discussing) is largely irrelevant (ie a second order effect) from a hydrodynamic standpoint in my experience EXCEPT as it relates to stability (see my comments earlier re: surfski designs) and therefore the ability of the paddler to go as hard as he/she can w/o checking for the entirety of the race.  In that case a wide tail typically creates a more stable platform and the paddler can go harder for longer w/o stability issues.  Of course, one can create additional stability in other ways as well (ie a wide tail is not the only way to make the board more stable as we all know).

One last thing... there is no doubt that C. Baxter wins many of the long open ocean races because of his ability to read the ocean, link swells, etc BUT he did beat Danny Ching this year at the BOP.  That win had little to do w/ swell riding and everything to do w/ ability, power, and stroke technique.

I have enjoyed this discussion and I hope that I have not burst the bubbles of those that hope the next best board (or the pricey light carbon model) will vault them from mid pack to the front but it simply won't happen.  But hell, buy that new board anyway... we all know how fun it is to get a new toy! And the good news is that there is a simple path to the front... more time on the water, stroke coaching and targeted hard training.

See ya on the water...

...Roger

[PonoBill]

It's nice to think a heavy board might be advantaged, especially since I stood my re-glassed 45 pound F18 up on it's tail to make some space in my warehouse this afternoon, and nearly suffered a hernia. Since the Bullet is gonna stay in Maui from here on, the F18 might see a lot of race and Columbia River duty next year.

I like to look at the extremes to judge the likely truth of a statement, and IMHO no example serves the "optimum design for conditions" notion better than an old-style Glide 14. An awful board under most conditions, but in the steep, short period Columbia River swells it's a little miracle.  The other end of the spectrum is the Starboard 12'2". A board that is NEVER optimal, but is always good--at least it is once you learn to stay on it.

[1paddle2paddle]

Roger, I was just playing a little devil's advocate.  I agree that it is pretty much impossible to design a board that can be great at everything.  Too many different conditions, and downwinding is so much different than flatwater.

IMO board/boat weight is more noticeable in downwinding than in flatwater.  Because there is a lot of stopping and starting in downwinding (and sometimes paddling up the back of a wave), the extra weight of a heavy board/ski can be very noticeable as I try to accelerate for the next bump.  Its also easier to control a lighter board with your body than to sling around a heavy craft with body movement, when you need to adjust the board to help catch a bump.  Now could this difference be measured?  It would be very difficult I think.

[LaPerouseBay]

Coach Roger is spot on with his notion of momentum, even in downwind conditions.  Like 1P2P writes, it's very difficult to test. 

My oc-1 had a small hole in it Monday, and took on at least 30 pounds of water.  I was amazed at how marvelously it glided through some tricky sections toward the end of a maliko run.  The run in to the harbor (as the tide drains it) is lumpy, crossed up sloppy garbage with big, fast swells across pier one.  It's usually a struggle for me to catch them in oc-1.  The heavy boat caught every glide effortlessly.

My guess is that (downwinding) a lighter craft is faster on average than a heavier one.  All the top downwinders here are on very light boards.   The Sup's Laird used to paddle in at Jaws were heavy.       

[ObviousSup]

In the automotive world there is a significant difference between sprung (board weight) and unsprung weight (rider). Being able to control the weight and where it moves in relation to a wave makes a big difference. Making a wild assumption I would think the same applies to paddleboarding.

[PonoBill]

There's no question that a heavy board or boat will manage chop better, and if you have the motor for it, the momentum will make it easier to catch some kinds of swells and waves--and much harder for others. If you need to accelerate it's going to be harder. If maintaining speed helps it will be easier.

Tow-in boards are shockingly heavy, some of them barely float. In that sense the analogy of unsprung weight is stood on it's head. In a car you want as little unsprung weight as possible so the wheels will react to the surface as quickly as possible. the suspension takes up the bumps and the much more massive car floats along. Tow-in boards use their weight to flatten the pounding of chop on the wave face because in this example there is no suspension other than the riders knees and ankles. the riders are trading compliance of the board to the surface for control and a little less beating of their knees and ankles.

[rpmooreii]

The entire system on a SUP is unsprung... this my comments re: losing 10lb of body weight being cheaper and more effective than buying a board 10lbs lighter.