Why not a standard speed scale?

I see a lot of questions and opinions about kayak speed. But useful, meaningful, reliable answers are very rare.

Why doesn't someone at CLC create a standard scale for comparing speed of different kayak designs?

That way, the answer to "which is faster, this model or that?" could be answered simply and objectively.

 

 


9 replies:

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RE: Why not a standard speed scale?

While such scales might be done objectively, simply is another mater.  First comes the issue of weight.  For any given design, the heavier the boat is the slower it is.  So, do we base these "scales" on the lightest recomended load, the heaviest, the average, or all three.  Once that is settled, each model would need to be towed at a range of speeds and the resistance meaured with a scale and load cell(preumably in pounds).  This would need to be done in dead flat water and still air - not easy to find and not very realistic in practice, but necesary if you are to get fair comparisons,  Wind and wave resistance is another whole issue that we won't even get into here.  The results of these tests would then be plotted as pounds of resistance versus speed.  It's pretty likely that these curves will cross, showing better slow speed resistance for some boats and better high speed resistance for others.  Do you plan to see the sights at 2 1/2 - 3 knots or do you plan to maintain a steady 6?  The missing ingrediant here is available thrust.  You and your paddle provide that.  BUT, how much thrust do you generate in a sprint?  on a day-long paddle?

The upshot is that someone could spend a lot of time generating a mountain of data, that while interesting to the engineers amoung us, would most likely be of marginal value to most folks.  For my money, I say the best bet is to get into boats that attrack you and paddle at your comfortable rate.  Pick the one you like best.  If you guess wrong, hey, you get to build another one!!

Paul

RE: Why not a standard speed scale?

Camper,

Q: How much sleep does a person need?

A: Five minutes more.

Similarly, which boat is faster? The one you don't have.

A bit more seriously, what's wrong with the guages at the bottom of the product page for each yak? Just not precise enough? I'm guessing that if they tried to get more precise than that, not only would they run into the problems that Paul mentions, but the peanut gallery wouldn't believe them anyway and would just want to argue some other interpretation of their own. Guess we just all need to come to O-Fest and race.

Laszlo

RE: Why not a standard speed scale?

We'll be there to show off the new boat and Susan will kick butt (yes it will get wet)

Dan 

RE: Why not a standard speed scale?

Camper,

 I think your question is valid. Yes, there are a lot of variables ex, weight of paddler, strength, wind, waves etc. But....

I have a SW17 17' 21"beam and want something "faster" Looking at NH 18' 20"beam well speed ratings on site list SW17 as "7" and NH as "5". NH listed under performance and SW17 under touring? Which one is faster? I'll bet NH,

For me to do a seat of the pants test, since I live 500 miles one way from show room  I would have to take time off of work send $120.00 for gas, plus food and lodging. So it is not always practical to test drive.  I had it narrowed down to two boats and traveled 200 miles to try one of them. No, NH's in my area to try :>(

Are comparisons between all boats or the classes that they are listed under? I do not want a double my money back speed number, again to many variables, but above numbers lead to confusion. 

Phil T 

 

 

RE: Why not a standard speed scale?

Camper,

Have you posed your question to the CLC folks? I'm wondering what their response would be. In my experience, they have been pretty good about responding to direct inquiries.

RE: Why not a standard speed scale?

czdan:  No, and it's a good suggestion. I will ask CLC by email if others on this forum agree that such a scale would be worthwhile. First, I would like to refine the idea based on the views of other forum readers.

Re: "Do we base these "scales" on the lightest recomended load, the heaviest, the average, or all three?" 

I have no preference, as long as the spec is reasonably useful to consumers.  it would not try to be a perfect scale, just a pragmatic one, just like for a car I can compare published "horsepower" of two cars as a baseline, but it would not tell the whole story.   

Re: "each model would need to be towed at a range of speeds and the resistance meaured with a scale and load cell"

This spec sounds good to me, but I am not an expert. Whatever evaluation method CLC specified, it would need to be cheap enough to administer to encourage publication for a wide range of boats.

Note: Consumers should be considered as experts on their own requirements (their weight, how they intend to use the boat,etc.) but not on marine architecture. 

"[Tow test] would need to be done in dead flat water and still air - not easy to find and not very realistic in practice

As a life-long sailor, I think I could help any designer who is having trouble finding flat water and still air :-)

Re: "Do you plan to see the sights at 2 1/2 - 3 knots or do you plan to maintain a steady 6?"

Another very good question about what would be the most useful spec for consumers.  Again, I would leave it to CLC. One option I suppose they could employ is a pair of numbers, one for casual paddling, one for strenuous. But I don't know that this would be necessary.

 

 

 

 

RE: Why not a standard speed scale?

Disclaimer: author is NOT a marine engineer, neither has he taken a course in fluid dynamics.

Some points for discussion:

Displacement boats are generally speed limited to the waterline length, yes?

Kayaks can exceed displacement (or hull) speed with enough applied force for short periods but this would require effort that would be beyond standard cruising.

So I'd imagine that there is a theoretical cruising speed associated with each boat that is directly related to length.

I would also imagine that a tow test would be more directly related to hull finish than any other factor.

 

 

 

RE: Why not a standard speed scale?

Jay,

Kayaks are not pure displacement craft, they slice as well as displace so they can easily exceed hull speed with modest effort for indefinite periods of time.

Hull finish has a very minor effect on speed.  The main effect of finish would be controlling the transition from laminar to turbulent flow, but due to the hull shapes required for other reasons (such as making room for a paddler), as well as the paddling itself, all the kayaks I am aware of operate in turbulent flow anyway.

Wetted area, the length to width ratio and weight are the main drivers, with sail area above the waterline making a large contribution when the wind is blowing.

Laszlo

 

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