Hydrostatistics Spreadsheet

This is an interesting spreadsheet from Kayaker magazine. You can sort by any column. I sorted it by 3 knots which I think is my cruising speed. It confirms how I feel about my current favorite boat which is a Prijon Eski. Cruising is effortless. Have fun, be safe.


How many of os do this?
“The waterdrag is calculated for fully loaded kayaks paddled on flat water. I haven’t seen any scientific papers descriping how these numbers apply to empty kayaks or kayaks paddled in waves.”

Agree, plus…
… pretty much ALL kayaks are effortless at 3 kts. Real drag differences where design matter begin a bit higher up the curves. (Wow! it’s been months since we’ve had the famous short boats are faster at slower speeds argument).

Let’s take another look at the numbers. Excluding doubles, the range of effort at 3 kts ranges from:

0.81 to 1.17 - a whopping difference of only 0.36 between some very different hulls.

At 5 kts it ranges from:

2.81 to 5.49 - a difference of 2.68 (that’s over 7.4 times more difference).

See what I mean? I may have missed some - but the point is the same.

My kayak’s not listed, but would be near the top at the 4-5 knots I tour at. I also don’t paddle loaded. Some flat, some not. Boat works for me.

Boats in similar class to mine that are listed (close to 18’ and over x 21" beam sea kayaks) are withing 0.05 of the Eski at 3 kts. Is 0.05 really an advantage over longer hulls? No one can even feel a 0.05 difference! I sure wouldn’t give up my 5 knot cruise advantage of 1.5+ easier than an Eski for it.

Numbers give a very narrow look at things, and so deserve a close look. Good to know, as long as you take them for what they’re worth in the context of where and how you paddle, and don’t extend the logic out to generalities (not that the original poster was - but the the discussion of drag numbers always brings out the short boat efficiency experts).

What I find interesting

– Last Updated: Nov-30-04 10:43 PM EST –

in that table is the lack of overlap in the columns, once you discard the few handfuls of really slow boats. So if you find yourself locked somewhere in the 4-4.5 knot range (steady for a distance, not sprinting) in an averagely decent boat, there isn't another boat in the table that will buy you more than a tenth or two of speed, for the same power output.

The other thing important to remember is the boring frictional resistance equation is a velocity-squared function. Everyone likes to talk about waterline length and wave-making hull speed making effort climb suddenly, but the effort curves climb quite steeply from the friction equation regardless of any hull-speed contribution.

Of course, the table is theoretical. I hope it's pretty good science because a whole lot of words have been written around those numbers, assuming they reflect the real deal.


Learning New Math
So if the Eski pulls 3.48 at 5 knots and the Hawk being the fastest pulls 2.81 at top speed the Eskis is .67 lbs harder to push at top speed. Since I spend probably 10% of my time at 5 knots and the rest at 3 to 4 I’m good with my boat. Are you paddling a Hawk, or do you have a motor?

Table lists drag in kg, not lbs,
despite kg being a measure of mass, rather than force, oh well. So you need to multiply those by 2.2. Then note the Sea Kayaker guideline that a 3 lb effort can be sustained by most reasonably fit paddlers, but 5 lbs sustained means you are somewhere in the higher percentile of ability.

Mike (I’m a 3 pounder, myself, maybe)

Why are you so bothered
by the facts? You obviously like to paddle fast. That is your thing, and that’s good. You should be in a long skinny boat!! Are you going to put a 110 lb. woman who can’t even lift a 50 lb. kayak onto her car into an 18 ft. kayak? How’s she going to turn the barge into even a 15 knot wind? No right or wrong here, just applying the correct boat to the person, and the conditions in which they will be paddling. The efficiency guys (I’m one)are meerly pointing out that long isn’t best for everyone, and in some cases is a poor choice. Relax

Meant to respond to Greyak

I disagree
My wife weights about 103/106 lbs, and she is neither a strong person nor a fast paddler, but she paddles effortless my Isthmus (17 by 20.5 and 48bls) around 5mph while touring.

To me, “the short boat” for “smaller paddler” does not make any sense…

A short boat will be faster for a small person if and only if its beam is proportionally reduce. The only boat for small paddler I know is the Huki S1-A but a bit too tender for most.



Why are you?
I was only talking the nubers - and they’re LIMITS. I was not promoting any particular hulls fro any particular paddlers or conditions.

Your see the words - but add your own meaning.

I pick hulls based on intended use/users - not numbers. I was ONLY commenting on how the differnces at 3 kts are extremely minor. Any tiny efficiency there are not reason enough to discount a longer hull. Your reasons might be - but aren’t about the drag numbers being discussed.

Try actually reading/contributing to a thread instead of attacking others with knee jerk commentary.

Yup. Narrower, not shorter…
…for efficiency - unless you want a play boat.

But which boat for which person & use is a different topic (several) than simple drag numbers. Anyone wanting to enter useless debates about “better” boats for certain types of paddlers or conditions should start a new thread. For some reason I don’t quite understand, people tend to take comments about specs out of context - and personally. It’s just math people.

We probably agree more than not
but are mis-understanding each other. I do find merit in Iceman’s comments. A longer, narrower boat may net the same wetted surface as a shorter fatter one. To me it’s not so much length affecting speed, as it is too much length being a hindrance to weaker paddlers in wind and waves. There are so many variables that need to be taken into account. I know a woman who loves her Arluk 1.8, and does very well in it. The same woman finds a Mariner II with it’s increased windage a real chore in wind. I just think length is the variable that gets over-emphasised. The least emphasis is placed on the paddlers fitness and skill. I think you might agree that many non-fit paddlers look to a longer boat to make them faster.

Uh oh, it’s happened again,

– Last Updated: Dec-01-04 3:40 PM EST –

someone claimed to be of no particularly special ability seems to be paddling a kayak at 5mph "effortlessly".

Although this may be a special case, since the paddler in question is quite lightweight. Wonder how the drag numbers compare for a 100 lb paddler vs a 180 lb paddler.


We agree completely, except maybe…
… on your last line (more below).

That’s why I took exception to your post - I had said noting to the contrary of your additional thoughts (those wider points had not been made as they open Pandora’s box as far as opinions go), yet you assumed by some very narrow comments I was also talking about the other characteristics, or all boats in all manner of conditions. I was not.

As to that last part on weaker paddlers: While some might look to faster hulls as a way around training, all I can say is good luck. If truly weak, they won’t have the power to take advantage of the faster hulls’ efficiencies at the speeds they were designed for. They’ll tour at fractionally better speed or with slightly less effort. Nothing more (and even that assumes they can handle the new boat equally well).

I’d say my Q700 only begins to have any meaningful efficiency advantage (meaning racing) over similar sized (and some longer) kayaks if you can hold it over 5.5mph, better at over 6mph. That requires a pretty decent paddler - and that puts you ahead of most already in similar class hulls. It’s still very efficient down at the 5 mph I like to tour at, but so are several designs. As you’ve said - it’s not all about speed. Other handling characteristics and overall quality make it a great touring boat even if never raced.

Heck, I was a stronger paddler on my 28" beam T160 SOT than I am now! I could hold 4.8 mph for 10-15 miles. Not “fast”, but near top end for a boat that wide and heavy. It would do no more without major effort, maybe 6-6.5 in a short sprint. Definitely “hitting the wall.”

Sure, I’m faster in my Q700, but not that much on longer paddles. It’s efficiency has allowed me to get weaker. Efficient is still better, and does not prevent/preclude training. That’s my fault. I rarely race though, so how fast do I need to be? I already have no similar speed paddling partners. Others are either slower and don’t paddle as far, or 1/2 a knot or more faster [Hex, Ice, …]).

Anyway, you may be right that people THINK they can buy speed. We’d probably all like to think so. I’m just saying you really can’t, not much anyway (unless you’re in a rec boat or short SOT). If you get speed in what you have first, then upgrade and keep hammering - then you get more speed. The new “faster” boat may allow more return for same effort (but don’t forget some speed is usually lost to more difficult handling for a while as you upgrade) - but it does not make the effort for you. Rather, it allows you to push a little harder since you’re no longer hitting the wall.

is the hawk the same one as clc’s kit?

– Last Updated: Dec-01-04 6:11 PM EST –

i would love to try one. also the cd extreme, most efficient at 4 kn. interesting that some of the hard chine boats (hawk) are so efficient.

Are faster B always less in other ways
Greyak and others are faster boats invariably harder to handle, to turn, to use in following seas and high wind, etc. If I read the posts, faster boats are only faster, i.e., less energy when in flat or nearly flat conditions and at speeds of 5 knots and up. Might you all also be saying they are actually more effort in many of the conditions and speeds most of us tour in? Hey, I am repeatedly confused by this stuff!

with a decent forward stroke
"“someone claimed to be of no particularly special ability seems to be paddling a kayak at 5mph “effortlessly”.”"

5mph is quite easy with a decent forward stroke whether I’m in my barge (Q600) or sprint boat. Aerobically, 5mph feels about like a brisk walk unless you try to do it in a boat that’s 14-15’ long and really wide.

I’m sure it is quite easy,
for you. But for how long have you been doing this activity and how often?

You think it would be easy for someone just starting out? (Who, incidently, is likely the sort of person starting topics like this.)

Mike (started a few of them myself in recent months)

Yes and No

– Last Updated: Dec-01-04 6:58 PM EST –

Kayak design is always a set of trade offs. That's why it's important to design for actual use and load, considering all anticipated variables and optimizing for use, not going most of any single characteristic without considering the impact on other factors.

A classic trade off is narrower and rounder hulls vs. wider and more squared ones (given same volume - narrower will also be longer/wider will be shorter). Thin and round are faster due to less wetted surface and less wave making. Narrow and rounder generally means tippier too. Wide and square have more primary stability (primary ain't everything though, particularly in waves), but secondary can be decent in either depending on design.

Speed does not = flat water use. Apples and oranges. Conditions bring in a lot more factors to design around. More compromises/optimizations, etc.

Surf skis are routinely paddled in rough water. K1's are more for flat. Both very fast. Both need good balance and a decent wing stroke.

Efficiency differences do matter more at higher speeds. Anything is easy to paddle slow. Very simple concept. Look at how close everything is at 3 kts on that table - and how much more difference there is between designs at 5 kts and above. At higher speed the design really matters. At low speed - all pretty much the same for effort - but depending on where you paddle handling in waves will be a bigger concern than speed.

If you don't regularly paddle over 3-4 knots. Don't even worry about this stuff. paddle what you like. Over that, shop smart - but don't ignore the basics of fit, feel, and suitability to the task at hand - whatever that is.

Sometimes Evans
This is my poorly stated point in the past. In truly big seas long, high volume, low rockered boats can be a real handful!! This makes sense, and in fact we are really talking two different sports almost. I think the QCC hulls are superb for what they are meant for. I doubt the designer would endorse them for outer coastal play in big, confused seas. They would do well in big swell conditions I bet. But heck yes, wind and rough seas can play hell on a longer boat, and for many people this leads to slower results, and lots of correcting. Case in point is when I used to guide long trips on the outer coast. You could put a weaker, small paddler, in a Coaster and they did great! Two summers ago we did a Brooks Peninsula trip where we had hurricane force winds for a while and were pinned down. I put a woman who was having a heck of a time in her Raven (big, long hull)in my borrowed proto Chatham 16. I got in her Raven. She was at the front of the pack for the two days she was in the Chatham! Now the CH 16 is the slower of the two boats on flat water. This was NOT flat water, and the winds were gusty. She netted FAR better results in the 16, and did not want to return it. Would I recommend that CH 16 to her for flat water workouts etc. No, there are better options for that. In the end it’s about looking at what you really want to do. So for some people who buy long thinking it means speed, they have no real speed advantage given their lack of power to drive the hull and benefit from it’s added length, and they in fact have added windage and leverage that can work against them. My opinions come from many years of teaching and instructing, and expeditioning. Have not all the answers, just lots of observation which is consistent with the math. If you want to go fast for real, then go for a full on fast hull, and learn to get comfy in it. Better yet, buy what feels good and go paddle. As your tastes change your boat may. You may need two boats, or three…