Analyse this, please (techn. vs. power)

-- Last Updated: Aug-03-09 3:29 PM EST --

EDIT - a *BIG* "snip -;) to shorten the original question and avoid confusion...

If I can maintain X mph average speed over 10 miles in a given kayak with low "hull speed" what average speed will I manage over the same 10 miles in a different kayak with high "hull speed"?

Assume no stability, ergonomics or other issues detracting - both kayaks allow me to use all my power for forward movement.

Looked at some hydrostatic numbers at:

Is my logic correct that if I look at the speed for a given fixed effort for the two kayaks I should be able to answer my question?

For instance:

- The Perception Sonoma requires effort (resistance) of 3.15 kg to maintain 4.5 knots.

- The Seward Epic requires nearly identical effort of 3.14 kg to maintain 5 knots.

??? ---> Does the above mean that if the two boats were just as ergonomic for me (allow efficient paddle entry, comfy, etc.) and I had no stability issues in either one of them, I would be able to travel at 5 knots in the Quest just as easy or for just as long as in I would be able to do it at 4.5 knots in the Sonoma? Of course, assume perfectly flat water and no wind of current, same wight of the kayaks and me in them (e.g. equal displacement volume, etc.)

That said, one more (unrelated) question - why do you think the Sonoma has this odd effort graph? It has a hump instead of a smooth increase in effort with speed (it is harder to paddle at 5 knots than CD Andromeda but easier at 6??? I understand a similar transition at very low speeds due to wetted surface. But at high speeds all other kayaks I plotted, once after about 4 knots, only diverge on the graphs. Meaning if one was faster at 4 knots compared to another, the difference b/w the two only increases with increased speed (diverges). The Sonoma on the other hand, begins to beat at 6 knots some kayaks to which it was loosing at 5. Could it be it starts to plane as it exceeds its (rather low I must say) hull speed early, being short and of certain hull shape? And the other kayaks just do not have enough speed range plotted to see the same. Unless the data is bad, of course. If it is right, planing was the only explanation I could think of...


You forgot to plug "age"
into your question !

Which is very important

There is a tremendous difference on how much a older paddler can train at high speeds in a week vs. a younger paddler.

When I used to run marathons and 10K’s in my late thirties and early forties, I would train six days a week with one day off.

As I got older, it was very noticible how I had to take more rest days or my performance would suffer.

The same holds true for biking and paddling.

I am a way over the hill paddler, so if I did more than one high speed/endurance workout combined with a lilly dipping one in a week now, I know my performance would suffer.

As far as comparing a QCC-700 with a surf ski ; there is none!

If you average 6 MPH in your sea kayak, you will average 7 mph on a ski.

Just my take



power and technique interact
technique does not make one move forward, rather the energy produced applied to the water in the direction that is 100% at 90 degrees to the direction of movement does.

So with power created being fixed, technique will allow you to do two things.

One, the amount of dysponesis, that is wasted muscle contractions that do not actually create forward power to the paddle will decrease allowing you to be what highly trained athletes can do, have a vastly reduced heart rate, lowered oxygen consumption, and use of more muscle groups allowing both more power production and more endurance with less waste and better recovery.

Two. more and more of that power goes to driving the boat forward rather than wobbling, pushing the boat up and down in the water, etc.

The more efficient the boat, the more the difference in your efficiency will result is more speed and faster times.

That said, water is approximately 600 times more dense than air, so remember there IS A REAL wall here, both in terms of maximum hull speed and your motor maxing out!!!

Age = 40

– Last Updated: Jul-31-09 12:17 PM EST –

You are right - age does make a difference.

But I guess my question was really intended to be more about this. If I stay at my current level of fittness, how much of an improvement I can expect due to better technique? Will I ever find moving the 18 footer through the water as easy at 6 mph average as I find moving the 13 footer at 5 mph average over a couple of hours... Or is this not possible only via technique development past my current level and I would need to also build more stamina and power to see this that...

speed training
The terms “fast” and “slow” boats typically refer to their maximum hull velocity and say nothing about the effort required to attain any given speed. Do I understand you to say that you have only just recently equaled the speed of your slow boat in the fast boat, with the same level of fitness? If so, that would imply that your fast boat requires more effort to attain the top speed of your slow boat (since presumably if you stayed with the old boat you would be slightly improving your max speed each trip due to improved technique), and much more effort to attain it’s own top speed, which you have not reached yet.

What you say makes sense in terms of the boat lengths. The amount of resistance you must overcome to move forward is the area of boat surface that is in contact with the water – the “wetted surface area” of the boat. Obviously an 18-foot boat has more wetted surface area than a 13-footer.

Therefore, it sounds like you have a lot of speed you can gain through simply increasing your strength and/or efficiency. This is supported by your statement that you have to rest more often in the new boat. (BTW, for max overall speed, you probably should pace yourself so that you do not ever need to stop paddling and rest, other than preplanned rest periods. You should paddle at your max SUSTAINABLE pace, and needing to rest means that you are wasting energy by trying to paddle too hard and then having to stop. If you do better with occasional rest, do it on a schedule like a hiker does, like 3 minutes rest at the end of every hour.)

To increase your strength, perhaps you should start a more challenging non-paddling exercise routine with emphasis on aerobics to increase your longevity.

To increase your efficiency, continue to study paddling technique as you obviously do. Also, you might sign up for classes or ask fellow paddlers you admire to critique your stroke, and you might attend or better yet participate in some races, so that you can study the technique of people who are faster than you.

If you are already doing things as you should per conventional wisdom, then it is going to be hard to coax additional gains from technique – however, it is worthwhile to pursue because such gains are “free”, i.e., you don’t have to get any stronger in order to get faster this way.

biking works well as a cross training exercise. I like intervals on the bike to prepare,along with pushups, crunches, and moderate weight training. If you have a GPS, check your speed. If you are running faster than your hull speed you are probably just wearing yourself out. I race a 700x, and 10 mile pace is 5.88 mph. I don’t think much more than that is reasonable over that distance.(for me anyway)

6 MPH average over 10 miles is good. It is also really hard to stay focused that long, and face the pain of continued hard effort.

For speed trials, find a good 20 minute course with distinct, permanent start/stop points. That’s about 2 to 2.2 miles. Those long, fast boats should be able to do 6.4+ MPH easily over 2o minutes. Track your times, and do quality paddles for the rest of your week. The other aerobic activities help when not on the water. Keep working on paddling technique. You have the motor you were born with, only so much power available, so try to use it wisely when trying for speed.

Some answers so far
Sure, in the slim long boat I do feel I am the limiting factor. That’s obvious and I’m not questioning that.

My thinking is, for non competitive paddler like myself with the equivalent of 2-3 times a week max water time and not much more else in terms of workouts for strength endurance, what’s reasonable to expect in terms of speed over say 10 miles?

I simply do not want / can’t dedicate more time or energy to gain considerable speed/endurance (for various reasons) so going that way would not happen, the way I see it. Will likely stay at similar fittness levels as today as far as strength/endurance, may be small gains…

I’ll try the 20 minute/2 mile test soon to see where it gets me…

Check the OP again - change of info, pls

Short answer, yes
In short, your assumption is correct.

The longer answer starts with explaining that kg is not a unit of force.

Why so fast?
What’s the big hurry? Take it easy dude.

kg is not a unit of force
of obviously. But that is what the referece stated they used to express resistance or pull presented by the hull in the water. Basically, how hard one needs to paddle to maintain a given speed. And this is a valid measure.

Think of it that to lift a certain weight against the earth’s gravity you need to apply certain force if you prefer. Of course you can convert these numbers to units of force needed to move that mass. But I doubt it will be more informative this way to most paddlers than the pull expressed in units of mass.

Not “fast”. "Efficient"
Speed is a dude thing, ya know -:wink: Though some of the local “dudesses” still beat me handily, so I guess it is not entirely a dude thing…

But to answer your question why interested in speed, here it is. Reaching the “theoretical” speed for my effort in a given boat is what I am interested, not simpy going “fast”.

I feel I am fairly close to what my short boat can do on flat water for me (the boat is becoming the primary limiting factor for sustained top speed). On the other hand, I am a good way off relative to what my longer and much less stable boat can do for me (I am the limiting factor much more than the boat at this point).

Knowing what I can expect to achieve in a certain boat for my effort is a threshold that I am interested in. I think it is good to be aware of this and not try to work too hard to exceed it as it can only lead to frustration or injury if you do.

big effort small results
You seem to be asking a hidden question, namely, at a given effort level what speed will a certain boat do, and since you are only so fit what will that be in different boats. Will it be dramatically different?

Answer, depends. Kayaks do not plane. Differences in efficiency are complex. Rocker, prismatic coefficient, narrowness, length of wetted surface, fishform, symmetrical, sweedform hull shape, etc. all account for less drag of hull,

BUT, some designs are actually MORE efficient below 4 to 4.5 K whereas they are LESS efficient above 4.5 K, while some that are MORE efficient above 4.5 K are somewhat LESS so below it.

Paddlers would be better to KNOW THYSELF and be honest about how fast they actually paddle either alone or in groups of friends, and have a boat that is the most efficient for the speed they actaully paddle most of the time.

OK, so let us say you are a lone paddler who loves to blast away two times per week, and you are able to do above 4.5 K most if not all the time in a Sonoma but are dogged about it’s ceiling hull speed of say 5K.

What happens at top hull speed is that more and more of your energy goes into the water but results in less and less increase of speed.

How much faster would a surf ski be? Quite allot depending on what you consider allot. A surf ski might go say 7K at the same energy of you ceiling effort in the Sonoma at 5K. So in one hour you would be 1.5 K further along. If this seems small, do not bother. If, it seems big go for it.

This is where folks decide it is worth it to have an epic 18 ft kayak etc.

You retain a boat that has seaworthiness and get the increased speed. NOT a surfski but pretty good.

Just remember that same boat at slower speeds will have somewhat more drag than an efficient hull with less wetted surface area at slower speeds of travel.

Hope this helps


– Last Updated: Aug-04-09 2:55 PM EST –

Trying to guess how fast I should expect to be able to go in the fast boat if I can go at a certain speed in the slow one. I think if the measurements on the chart are done in comparable conditions, then it probably answers my question.

So, if I'm well below the "theoretical" speed at which the fast boat should go at a given effort that I know I can maintain in another slower boat, that means I suppose that I need to work on technique in the faster boat to gain the same efficiency as I have in the slower boat and not waste energy on balance.

Of course, no one can decide for me how fast is fast enough. I was just curious if there is any flaw in my reasoning about interpreting the hydrostatic data...

As for "boats not planing" - they do when they go fast enough, for most of us that would be when pushed by wakes and waves or when surfing ;) And for some individuals owning a hydrofoil kayak - they can do that on flat water for a few hundred yards apparently. Check youtube for a cool demonstration of this on a K1 planing above the water on hydrofoil wings and beating a 4-person rowing shell at that.

"sonoma dip"
While there could be plateau in the resistance curve due to the destructive interference of bow and stern waves, I would contribute the “Sonoma Dip” to the human error :wink:

If you look quite a bit lower you will notice that Coaster has considerably higher resistance at that speed. I would put my money on Coaster as the more efficient design. It also is of comparable length, but probably longer water length, since Sonoma has huge bow overhang.

as far as planing goes
I believe it is limited to boats only with a large surface area in the stern. As the bow of the boat rises, the stern must have enough surface area to support the boat. The stern of a kayak or canoe should just sink after it reaches hull speed. Not having ever put a motor on my kayak, I have not tested this. However in a boat without a square stern, I believe the boat would continue to stand more and more vertically as speed is applied, until the stern would be driven beneath the bow, and it would tip over backwards. This is only my understanding on the matter of hull speed, if I am wrong, correct me. So far though I don’t believe a canoe or kayak can plane out in a technical sense.

IT is a
thrust to drag ratio thing.

You have the basic concept though. For a constant thrust force, the one with the least drag will be faster. The last column is probably the most useful for those that are wishing to cruise at a healthy, but not race speed. Maintaining anything above 4 in most boats is going to require sustained effort. This is where your age and conditioning will be important.

I find it interesting, leaving the double yaks at the bottom out of the mix, that the 3 knots effort has the lowest spread. This is basically the lilidipping range, where the majority of paddlers spend their day. If easing along listening and watching nature is your main goal, your boat choice can easily be satisfied by selecting a boat by color, fit, comfort, stability or you just think it looks sexy.

If you are looking for something sporty that you might mainly race, then you first need to get conditioned enough to sustain the hull speed the boat is capable of for long periods. Then choose one of the fast ones in the six knots column.

But while this is all very scientific and probably useful for designers and racers, most folks would be hard pressed to actually feel the difference. If they could be blindfolded and fit comfortably, they would have a tough time telling you they were in boat A, B or C. I am sure some will pipe in that their highly calibrated hynee is tuned to detect the subtleties.