Author Topic: When is an unlimited slower than a 14'?  (Read 17244 times)

ukgm

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Re: When is an unlimited slower than a 14'?
« Reply #30 on: January 10, 2017, 11:51:38 AM »
a 14 foot board starts to really feel a lot of wave drag at about 5.8 mph. If you can consistently reach and hold something in the range of 5.5-5.8 mph with a board of this type, then you can probably go faster with an unlimited board. If you can't, you won't. 

The unlimited board (say 18 feet) will have more skin friction because of the greater surface area exposed to the water, but wave drag doesn't start exceeding skin drag until about 6.5 mph. Understand that total drag for an unlimited will generally be GREATER than a 14' up until 5.5mph. After that, the total drag of the unlimited is less.


It's interesting that, at below hull-speed, total drag on a shorter board could be less than on a longer board. It would be interesting to see the "drag vs. speed" plots for different board lengths, and where the cross-over point is. Even more interesting to see the same plots for different water depths.

It was one of the basic tests I did for a SUP mag article a while back. Take your board to a lake a perform a series of intervals at speeds spaced around 0.5kph apart from circa 6kph upto around 10kph. Draw a graph when you get home and you should clearly see a deflection point whereby the drag is starting to overwhelm your increases in power. I did this as I felt the right board for a Baxter et al. may not be the best board for me being Joe normal - even if you find the board perfectly stable. I use this method to compare boards too.

Eagle

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Re: When is an unlimited slower than a 14'?
« Reply #31 on: January 10, 2017, 01:07:18 PM »
"I’m not buying this “deeper is more drag” myth being tossed around here either. The basic parameters are shape, surface area, depth."

yugi - just to clarify fin shapes from Futures speed potential perspective - a) low profile depth b) wide base tracking c) swept back shape less leading edge = less drag = feels fast

This is advertised as their fastest fin for flat water. I have used this fin for a few paddles.  It did feel fast and can confirm it was not suited for surfing down and across waves.  Was the carbon version.  If we had pure flat water here -> would probs have this fin.  Ok back to UL vs 14 and speed tests.

https://youtu.be/ZW-41toWXIU
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ukgm

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Re: When is an unlimited slower than a 14'?
« Reply #32 on: January 10, 2017, 01:18:17 PM »
"I’m not buying this “deeper is more drag” myth being tossed around here either. The basic parameters are shape, surface area, depth."

yugi - just to clarify fin shapes from Futures speed potential perspective - a) low profile depth b) wide base tracking c) swept back shape less leading edge = less drag = feels fast

This is advertised as their fastest fin for flat water. I have used this fin for a few paddles.  It did feel fast and can confirm it was not suited for surfing down and across waves.  Was the carbon version.  If we had pure flat water here -> would probs have this fin.  Ok back to UL vs 14 and speed tests.

https://youtu.be/ZW-41toWXIU

I've always been a futures fan but I have found all of their fins to fit sloppily in the box.

By the way, I tested the plastic version of that fin for flatwater purposes and it did not do very well. I'm not sure whether it's apparent flexibility (or box fit) may have been to blame but I was disapointed.

Eagle

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Re: When is an unlimited slower than a 14'?
« Reply #33 on: January 10, 2017, 01:30:09 PM »
Yeah - some of my fins do not even fit at all in some of my boards.  Others I have to add epoxy to make them a touch wider.  The carbon version was quite stiff and seemed to be an ok fin.  Luc let me try his as he was looking for someone to buy it from him.  I have no Futures fins in my quiver.
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supuk

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Re: When is an unlimited slower than a 14'?
« Reply #34 on: January 10, 2017, 02:08:29 PM »
futures and fcs fins will not be designed to fit perfectly in to the centre fin boxes which the windsurf brands use as they are are a different type and are a fraction winder and make for a sloppy fit with fins from the surf brands. FCS normally supply some shims with there fins for this however there are other ways also that work.

Eagle

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Re: When is an unlimited slower than a 14'?
« Reply #35 on: January 10, 2017, 05:21:45 PM »
Here is a good vid showing speeds of a UL single and tandem vs 14s.

http://www.racethelakeofthesky.com/2013-results-1/

https://youtu.be/B4cN7y2qJtI
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TallDude

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Re: When is an unlimited slower than a 14'?
« Reply #36 on: January 10, 2017, 07:03:08 PM »
FYI, Thomas's unlimited during that Tahoe race was shaped by Craig Richmond. Riviera was more or less the sponsor. I'm surprised Thomas did as well as he did, given all the buoy turns. I hate distance buoy turn races on my unlimited. I prefer 20k or more length races (with maybe 2 buoys) on an unlimited. The glide becomes more critical in longer distance races. Usually after 8 miles or so, the unlimiteds really pull away from the shorter boards. Now add quartered wind, and the story changes.   
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Eagle

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Re: When is an unlimited slower than a 14'?
« Reply #37 on: January 14, 2017, 06:00:58 PM »
"Understand that total drag for an unlimited will generally be GREATER than a 14' up until 5.5mph. After that, the total drag of the unlimited is less. At 6.5mph the 14' has a huge amount of drag that only the very best paddlers can overcome. Going 7mph unaided by current, swell, or wind is a real accomplishment."

This makes sense why on a DW run the Bullet 17.4 easily pulls away from 14s.  Here is some interesting information regarding length and weight and power and hp etc -

http://www.keelhauler.org/khcc/seakayak.htm

http://www.seawardkayaks.com/reviews/30_347958amnik_14.5_0211.pdf

http://eodg.atm.ox.ac.uk/user/dudhia/rowing/physics/weight.html#section7

http://www.paddlinglight.com/articles/the-lightweight-secret/
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Dominator - Touring Pintail - Bullet V2 - M14 - AS23

Eagle

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Re: When is an unlimited slower than a 14'?
« Reply #38 on: January 15, 2017, 11:53:02 AM »
It seems possible that some sort of more objective evaluation could be done for SUP comparisons as well.  For my purposes though - a simple short OTW subjective demo is plenty - but for others this sort of data might be really useful when buying sight unseen and untested.  Was just out yesterday and swapped boards with my wife - and it was startling the difference in tippy vs speed btwn our AS23 and Dom.  The Dom felt incredibly stable but definitely had a defined speed limit.

http://www.expeditionkayaks.com/rapier-review.pdf

https://www.seekajak.ch/_media/19-newsletter-kustenkanuwandern.pdf
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Eagle

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Re: When is an unlimited slower than a 14'?
« Reply #39 on: January 18, 2017, 03:31:17 PM »
Perfect example where an UL simply pummels the waves ahead.  Much faster and easier vs a 14 on average - and a lot more stable as well.  Kinda reminds me of the Bullet 17.4 ride.  Beautiful how those waves become nice launching pads.   :)

 
« Last Edit: January 18, 2017, 03:36:28 PM by Eagle »
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yugi

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Re: When is an unlimited slower than a 14'?
« Reply #40 on: January 19, 2017, 05:36:00 AM »
D.C. Is cranking


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photofr

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Re: When is an unlimited slower than a 14'?
« Reply #41 on: January 30, 2017, 10:00:45 PM »
I think the greater weight of the unlimited board vs a 14' also has and effect on speed in flat conditions. I've paddled the Bullet 17-4 and the Bullet 14 on consecutive days in flat ocean conditions and just the shear weight difference of the 17-4 tires you out much quicker than the 14.

My UL Sprint weighs less than 10kg so I doubt that weight is an issue.
Side wind will slow you down - as a general rule, other than that, I must admit that my UL is always faster than my 14 footer sprint.

I am however blown away by the number of people comparing board speeds - or different surfskis for that matter. It is my experience that a super efficient ski or SUP will cut water so well that you will feel it's slower. In most cases, however, testers fail miserably: boards are compared on different days, and even on different bodies of water.

Same paddler, 4000+ km on my UL, ABOUT 2000 on my 14x23, a great many same comparaisons, and I can only tell that on average, my UL averages 12% faster - even upwind.
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SUPflorida

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Re: When is an unlimited slower than a 14'?
« Reply #42 on: February 02, 2017, 12:43:10 PM »
This thread is causing a paradigm shift in my thinking about SUP.
It's one of those moments when a bag full of puzzle pieces come together. A moment when you lift your head up from running with the herd and realize why it's heading in the direction it is...and it's not necessarily for the reason that are purported by some circles.

It is becoming more and more obvious that the 12-6" to 14' boards are that size for a far better reason than "12-6" was the biggest blank Clark foam made" or 14' is some arbitrary length tha Naish choose early on to screw with the competition.

Drawing a bell curve of the general population that participates in water activities (figuratively speaking). Eliminating the fifteen percent of both extreme ends. Factor in age, physical stamina and the realistic speed someone is going to be able to sustain over a distance...throw in a little rocker so it's good for something other than a mill pond, and your going to end up with an ideal somewhere between 12'-6" and 14'.

Will a longer board have a theoretical higher top speed?...absolutely...will 90% of the median population (people that have a job and a life beyond just paddling SUP) ever reach that potential for more than a few 100'yds? Not likely.

Face it , in grand scheme of things SUP is a snail slow sport. I have know that from the get go. Moving forward I am going to concentrate on a board that will give me the most "speed over bottom" with the least amount of effort....rather than a longer board that I have to drag around all the time just to have "the potential" to go faster.

So here is my premise... the new target is the easiest board you can push through water at your average sustained speed...when your feeling frisky you can dig in and push past hull speed until you run out of gas...better than dragging a longer board around all the time (figuratively and literally) that has too much skin friction for your weight, personal horsepower and personal average/sustained speed limit.

All the pros are pushing past hull speed anyway...and Kai, Conner, Travis, and Candice can probably kick all our butts on a 8' sinker wave board while we are on the latest and greatest race board ( maybe slightly exaggerated...but not by much ::)p ::))

Like putting a tired Honda 4 banger with 500K miles on it... in a Maserati isn't going to accomplish anything other than make a lot of unproductive work :P ;).

Obviously this does not apply to those substantially over 200 lbs., those built like Arnold Schwarzenegger (in his prime...not now ;))...or to Photofr...lol




PonoBill

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Re: When is an unlimited slower than a 14'?
« Reply #43 on: February 02, 2017, 01:01:23 PM »
You should try actually drawing that curve. It comes out closer to fifteen feet for the median. The average weight of American men is 195 pounds. If you stick with men only, the curve gets closer to 15.5 feet for the median given an athletic power to weight ratio (assuming ten percent fat). At least that's what I remember. I did the math a few years ago when we were all arguing about 14 feet being the limit for race boards--back when it mattered.

I never tried to add women to the mix.

Maybe that was more like ten years ago. Back around the time that some folks were seriously debating that waterline length meant anything.
« Last Edit: February 02, 2017, 01:03:26 PM by PonoBill »
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

Area 10

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Re: When is an unlimited slower than a 14'?
« Reply #44 on: February 02, 2017, 01:03:14 PM »
I think most people could go 15ft and still be faster. I think that it's only once you get over 16ft that the board starts to become too much for many, especially in surf or tricky conditions.

I reckon Starboard probably had it about right in the early days with the K15. Also, the Starboard Point was 14'8".

So 14 is probably just a bit too short to be the optimal "Everyman in all conditions" board IMO.

 


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