Aiming at better designs

[photofr]

photofr--a couple thoughts generated from what you've said:


--going longer is like a magic bullet that solves so many problems.  Not that it's better for everyone or even most people, or good for all types of paddling,  But when it is an option, it's so much more effective and simple a solution than making endless tiny other refinements to designs.  It's like if you designed a house that didn't have enough room in it, then spent endless effort designing built-in storage, fold-out beds, etc. and someone came along and said, "Why not just make the house bigger? It'd cost you half as much and work a lot better".

Very cool example about the small house / not enough room…
For the record, I really love SUP - I have merely spent nearly 30 years on a surfski, and only 12 months on a SUP - but I am not blind ahahah. SUP is super fun !
After paddling more than 2500 km on a SUP, I believe I am able to safely compare both crafts (surfski & SUP).

Just for kicks, I'll throw this out there:
My first board was a 14 footer. I found it very sluggish, and I am a feather weight paddler, so go figure.
My third board was a 12'6 x 24; it felt like I was on a boogie-board making my way on an outside set at Makapuu. 

[photofr]

OFFSHORE:
The other day, I was thinking about the X0 14’ board again; okay, perhaps I was dreaming

STANDING AREA
You are right about lowering the standing area; it will make the board a lot more stable. I have proof of this with my 17’6 x 23” that has the lowest deck of any board I have tried. To compare, I own and have paddled a bunch of km on my SB Race 14’ x 25” which has a very high deck. The board is fun (super fun for me actually) but barely more stable than my 17’6 x 23”. The Race 14 x 25 feels like I am standing high above water, which I am considering that I had to change paddle and add 4.5 cm to my paddle.

NOSE
The bow of the X0 does start to look like it “should”. Perhaps adding a little more volume would even be better.

LENGTH
This is also a critical part. Strange that the board came in as a 14’ – and not a 20’. Here’s my take on it: paddling inside well enclosed bay or lakes DW, a shorter board can be a lot of fun. For everything else, you want length.

Naval experiments in the US have yield that Length to Width RATIO was to be somewhere between 10:1 and 20:1 – and definitely not below 10:1 if you were looking for speed / efficiency. I’ll simplify those numbers using real examples: surfskis that have been trued-and-tried for over 50 years – their ratio is always at least 10:1, where the fastest human powered crafts seem to be at precisely 15:1.

Surfski Examples:
Fenn Spark: 6.44 m x 0.42 m – (ratio of 15.33:1) – 21.2 feet x 16.5 inches.
Epic V14: 6.4 m x 0.429 m - (ratio of 14.92:1) – 21 feet x 16.9 inches.
Fenn Elite Double: 7.45 m x 0.46 m – (ratio of 16.2:1)
Think Uno Max: 6.45 m x 0.43 m – (ratio of  precisely 15:1)

Following the path of Naval Experiments, what we now know about human craft through practice of trial-and-error, and following trued-and-tried surfski samples that have hit the water, STAND UP PADDLE boards should also be 15:1 – at least 10:1 (length to width ratio).

For the best glide, theoretically, a 26” wide board should also be at a ratio of 15:1, thus giving us: 390” x 26”, or 32.5 feet x 26”.

The following surfskis have a ratio of nearly 10:1, and they are still quite fast.
Think EVO II: 6.25 m x 0.47 m – (ratio of 13.3:1)
Epic V8: 5.48 m x 0.54 m – (ratio of 10.15:1)

In theory, then, a 26” wide board could be at a ratio of 10:1, thus giving us:
260” x 26”, or about 21.6 feet x 26”.

My experience tells me that if you are going to have a board that long, it will also need to be light – as light and as stiff as a surfski.

We have all noticed how a longer board also provides a little more stability, so perhaps we could aim at a rather stable board that would be only 25” in width... yielding the following minimal measurements:
21 feet x 25” – under 10 kilos (for a close to 10:1 ratio)

Starting to feel the glide…

[Off-Shore]

Photofr. Great info and when I see you stand up paddling that Surfski it begs the question how fast can you paddle it? Whilst the V8 which is the first and only Surfski I have paddled is relatively stable and I would imagine standing up and paddling one would be hard and tippy and it might be better to bend one knee and rest on it...

So if you could build a SUP at a 10:1 ratio what do you think is the optimum stable bottom shape?

Maybe it would look like this..

[photofr]

While I want to aim at going faster on a SUP, I also want it to be accessible to many paddlers. For this reason, I am not necessarily looking into paddling a 17' x 19" SUP, and I am not looking into paddling a surfski that is 22' x 15".

Keeping a SUP at a ratio of 10:1
We could be looking at 21 feet long by 25" wide, with the following hull criteria:
- Tall nose for volume
- Narrow nose for water penetration
- flat hull for stability
- widest point behind the paddler to ease water entry of the paddle up front on the narrow end
- no much rounded rails… as this will make it more tippy… so only SOME rounded rails for more speed (again, within reason)

Canoes like the one you pictured had a length LIMIT… that's why they had to go so narrow to accomplish the minimum of 10:1
Remove the length limit, and you will get back your stability.

Hope this helps.

Paddling a surfski was just for fun…
Its hull was rounded, so lacked stability.
I was able to get to 12.7 km/h hour during one of my sprints…you can see my bent paddle shaft in the image, but it doesn't mean much.
The boat was only 16' long, and the standing area was nearly nonexistent.
Can't really use that to say it was good or bad… it was again just for kicks.
It's a far reach from a 10:1 ratio to begin with… that was a V6 from Epic Kayaks.

[yugi]

Your dream come true, Photofr. Everything you wanted: long, narrow, rounded rails, hollow and, bonus, it's french. Extra bonus: even peeps who don't live on the beach or have a spot in a crew boathouse can store it.

[photofr]

That's great
It looks like it's only 15" in width though…
…and only about 18 feet long.

[yugi]

call l'Ours and ask for a longer, and maybe more stable one then. Anything goes in inflatables and l'Ours might go with your ideas.

[Area 10]

With respect, I think this discussion is missing the bigger picture.

We already know what makes a SUP fast. A fast SUP is long, narrow, light, pointy at both ends and with rounded rails. It looks like all the other paddle craft that are fast in water.

A board like that is also expensive, hard to handle in winds, tippy, prone to breaking in surf, a disaster to transport and store, has little resale value, and very few people can make one.

Long ago in SUP, the community made the decision via their purchasing power, to paddle shorter, slower, cheaper, and more easy to own and versatile boards. This is part of the reason why SUP is FAR more popular than Surfski.

SUP will always be slow because we use a single blades paddle and we stand up. This is highly inefficient if your goal is speed. So we decided to concentrate on FUN, accessibility, low cost and versatility rather than speed.

I think that was the right decision. I have two UL boards and I love the glide and speed that they give. I wish there were more around. But I'm the only person in my paddling group who likes them, and several of my friends are actually slower in the real world on them than on a 14. In some conditions I am too. I believe that this years' M2O showed how relatively little advantage the UL boards have unless you are in truly flat water or have the wind behind you. In very messy cross-wind conditions with surf on the way in and out you need to be very skilled and strong to make them fast. Even getting an UL board to the waters edge can be a challenge in high winds. And then there's the drama of a rudder, which can break, needs skilled maintenance, and a lifetime of paddling to master. And you can't take your UL board overseas with you.

So, basically, as a community we tacitly kinda decided not to go down that route. There are proportionally fewer UL boards on sale now than there were in 2011. They just didn't sell. Who really cares about going 7mph rather than 5mph? We are still dog slow.

Our references instead are more closely aligned to traditional paddleboarding than surfski, which is why the ISA World Championships combine both in one event.

So there really is NO debate about how to make SUPs faster or more stable, in principle. It's just that making them faster precludes a whole lot of things that we like about the sport such as it's simplicity and ease of board handling. So for racing we have decided to aim to be the fastest of the slowest on the water.

[raf]

With respect, I think this discussion is missing the bigger picture.

We already know what makes a SUP fast. A fast SUP is long, narrow, light, pointy at both ends and with rounded rails. It looks like all the other paddle craft that are fast in water.

A board like that is also expensive, hard to handle in winds, tippy, prone to breaking in surf, a disaster to transport and store, has little resale value, and very few people can make one.

Long ago in SUP, the community made the decision via their purchasing power, to paddle shorter, slower, cheaper, and more easy to own and versatile boards. This is part of the reason why SUP is FAR more popular than Surfski.

SUP will always be slow because we use a single blades paddle and we stand up. This is highly inefficient if your goal is speed. So we decided to concentrate on FUN, accessibility, low cost and versatility rather than speed.

I think that was the right decision. I have two UL boards and I love the glide and speed that they give. I wish there were more around. But I'm the only person in my paddling group who likes them, and several of my friends are actually slower in the real world on them than on a 14. In some conditions I am too. I believe that this years' M2O showed how relatively little advantage the UL boards have unless you are in truly flat water or have the wind behind you. In very messy cross-wind conditions with surf on the way in and out you need to be very skilled and strong to make them fast. Even getting an UL board to the waters edge can be a challenge in high winds. And then there's the drama of a rudder, which can break, needs skilled maintenance, and a lifetime of paddling to master. And you can't take your UL board overseas with you.

So, basically, as a community we tacitly kinda decided not to go down that route. There are proportionally fewer UL boards on sale now than there were in 2011. They just didn't sell. Who really cares about going 7mph rather than 5mph? We are still dog slow.

Our references instead are more closely aligned to traditional paddleboarding than surfski, which is why the ISA World Championships combine both in one event.

So there really is NO debate about how to make SUPs faster or more stable, in principle. It's just that making them faster precludes a whole lot of things that we like about the sport such as it's simplicity and ease of board handling. So for racing we have decided to aim to be the fastest of the slowest on the water.

Best post ever.  5 *s

[PonoBill]

A great post indeed A10. And lots of food for thought.

The 14' issue was actually decided by Naish but the market supported it. I suspect a distribution curve of paddlers centers around 190 pounds, which is reasonable for a 14' board. I don't think people thought slow was OK, in fact I doubt that most buyers have any idea of how limited that length of board is, or that there is a perfect length and width for them that would make them as fast as their combination of muscle, weight, and balance permits. And it would rarely be 14 feet.

The 10 to one ratio is well explored in naval architecture. If you find some old books where people actually cared about that you'll find it mentioned many times. It's the ratio of length to width where the bow wave weakens and it's origin starts moving back along the hull. I've never found a description of the mechanism, just the phenomenon, but it's easily seen with surfskis. The effect is to flatten out the curve of wave drag vs speed, and in essence make the hull speed "limit" less limiting. On shorter, tubbier hulls the curve is very steep and functions like a brake at specific speeds. It also functions as a brake on planing hulls, which is why a SIC Bullet or a surfboard is such a slug in flatwater.

Wikipedia has a nice entry under Hull speed. I trimmed all those unattractive equations out--you know, math:

Hull speed or displacement speed is the speed at which the wavelength of the boat's bow wave (in displacement mode) is equal to the boat length. As boat speed increases from rest, the wavelength of the bow wave increases, and usually its crest to trough dimension (height) increases as well. When hull speed is reached, a boat in pure displacement mode will appear trapped in a trough behind its very large bow wave.

From a technical perspective, at hull speed the bow and stern waves interfere constructively, creating relatively large waves, and thus a relatively large value of wave drag. Though the term "hull speed" seems to suggest that it is some sort of "speed limit" for a boat, in fact drag for a displacement hull increases smoothly and at an increasing rate with speed as hull speed is approached and exceeded, often with no noticeable inflection at hull speed.

The concept of hull speed is not used in modern naval architecture, where considerations of speed-length ratio or Froude number are considered more helpful.

As a ship moves in the water, it creates standing waves that oppose its movement. This effect increases dramatically in full-formed hulls at a Froude number of about 0.35, which corresponds to a speed-length ratio (see below for definition) of slightly less than 1.20 (this is due to a rapid increase of resistance due to the transverse wave train). When the Froude Number grows to ~0.40 (speed-length ratio about 1.35), the wave-making resistance increases further due to the divergent wave train. This trend of increase in wave-making resistance continues up to a Froude Number of about 0.45 (speed-length ratio about 1.50) and does not reach its maximum until a Froude number of about 0.50 (speed-length ratio about 1.70).

This very sharp rise in resistance at around a speed-length ratio of 1.3 to 1.5 probably seemed insurmountable in early sailing ships and so became an apparent barrier. This leads to the concept of 'hull speed'.  Wave making resistance depends dramatically on the general proportions and shape of the hull: many modern displacement designs can easily exceed their 'hull speed' without planing. These include hulls with very fine ends, long hulls with relatively narrow beam and wave-piercing designs. Such hull forms are commonly realized by some canoes, competitive rowing boats, catamarans, fast ferries and other commercial, fishing and military vessels based on such concepts.

Vessel weight is also a critical consideration: it affects wave amplitude, and therefore the energy transferred to the wave for a given hull length.
Heavy boats with hulls designed for planing generally cannot exceed hull speed without planing.

Light, narrow boats with hulls not designed for planing can easily exceed hull speed without planing; indeed, once above hull speed, the unfavorable amplification of wave height due to constructive interference diminishes as speed increases. For example, world-class racing kayaks can exceed hull speed by more than 100% even though they do not plane. Semi-displacement hulls are usually intermediate between these two extremes.

Anyhow, there is no secret to designing a proper hull for an individual. Given their weight, trainable muscle, and balance ability the design effort is fairly straightforward and follows research that was more or less put to bed over a hundred years ago.

It makes me personally grumpy to see the sport engaged in a slow race, and I consider 14 feet to be a particularly bad length to hang the sport on. One more foot would have moved it into a much more feasible length to width ratio for rounded rails relying on secondary stability (18" at 10 to 1) and two more would open the door for athletes like Kalama, Patterson, and Rojas. But it is what it is. Fast 14 footers will be 17" at the waterline and will be paddled by racers weighing less than 180. Everyone else is mid pack or at the back of the drafting train, unable to move up.

One minor correction--it's width at the waterline that matters for the "magic ratio" and moving the maximum width back to the paddlers feet has beneficial effects even if the width at max makes the ratio less than 10-1. It's one reason Speedboards are so fast even when they're tubby in the back. The rounded rails of surfskis yields a narrow width in the water. the deck width doesn't matter, it's the waterline width that counts. A flared hull gives secondary stability by getting wider on the side the hull is tipped towards. One reason why surfskis feel so unstable but can be caught before they flip.

[mrbig]

Props to you Area10! Case closed class dismissed..    

[Weasels wake]

At the risk of me loosing out on a multimillion dollar future, like that would happen, here's a brain storm that I've had ever since I saw one of these~

Remove the wheels, turn it sideways, and install it inside of a SUP board for added stability, the Segway SUP board, or whatever.

[photofr]

Everyone would love to go faster on a SUP, and many at the risk of making it impossible for the average Joe to really enjoy the sport because of stability, or the lack there of.
I am not talking about that, AREA10, or perhaps you misunderstood.

Boards can be faster and more stable, therefore more accessible on all levels.
That doesn't at all mean they cannot also be cheaper, or affordable.

Let's keep in mind that currently, tiny changes are taking place to try to do the "impossible", which is turning a 12'6 board much faster. Designs change every year, and we (the consumers) are faced with high board prices, mainly because of this.

Currently, SUP boards are more costly than most Surfskis… so we can't even use that as valid reasoning.

In all, you make very valid points, but I feel they are taken completely out of context.
For instance, how is it that a 14' board is any easier for me to handle on a super windy day than my surfski

Granted, surfski remains a small and tiny niche of paddlers. The reason is completely different from what I have in mind for 10:1 ratios on SUP.

Or, a different prospective:
Surfski: steep learning curb, lack of experienced instructors to take care of new comers, elite boats that are way too difficult for new paddlers, etc…
SUP 10:1 ratio*: super easy for any intermediate paddler, easier on side wind conditions, safer in open water, etc…

* 10:1 ratio would be a 21 feet x 25" SUP, that even my mother would be able to paddle. As it stands, I can't exactly see my own mother paddling a 12'6 x 25" of anything.

[canuker]

I haven't heard much talk about shark skin bottoms. Develop a light film that adheres to the bottom like rail savers and has the characteristics of those outlawed competitive swim suits. Retrofited speed. ...

You're on the right track! But unfortunately a study done at Harvard has found that Speedo's "Shark Skin" technology to be not as useful as previously thought. Apparently the "skin" aspect has nothing to do with the increase in speed in swimmers but it is actually the tightness of the suit promoting better posture and better circulation. The researcher claim's that the properties of shark skin only increase speed when applied to a highly flexible figure, such as a shark, meaning that SUP's (sadly) won't benefit from it...... Good for nothing sharks....

[stoneaxe]

What a great post A10....should be made sticky. Can we stop talking about this shit now and get back to the fun part....

I do enjoy the discussion on design but for better or worse unlimiteds are being relegated to a niche extreme. I wish it weren't so but it is what it is.