I paddle both…
My “rec” boat would be an Old Town Castine. Very useful 12’9" poly hull for rocky stuff or for clearing paths on forest creeks.
On the other end of the scale, a QCC700. 18’ of pure glide.
If I’m going for a distance, there is no comparison. Return on expenditure of effort is very obvious. Every paddle stroke shows it. Going against a current magnifies the difference. Long and sleek goes further with less effort. Short and fat is fine for down stream floats or poking through the swampland. Not so much for the big water.
I’d venture if I did an up and back paddle on a river like the Rainbow or Silver, my time difference between the two would be less notable than the wear and tear on my body.
If you live in or visit Florida, you’re welcome to paddle whatever is in the yakshak and see for yourself!
T
good to know
Thanks all, just what I was looking for (and what I sort of expected).
Although I don’t do a lot of sea kayaking trips, when I do, I like to push myself - 10-15 miles so it seems like spending some $ on the right tool for the job will save time paddling and make things quite a bit easier.
My Castine is a great brush buster.
Seems to love choppy water. Faster than most rec boat of the same length, but it won’t touch my QCC400X, Epic 16X or Perception Sonoma 13.5 for speed and efficiency - too fat.
“over a couple of hours"
My 18 foot kayak will average 2 mph faster then my 9’-6” kayak.
That is just lilly dipping
Jack L
Tow Tank
Outside Washington DC the Naval Research Lab has a tow tank (in a really long building) for dragging ship models to assess hulls, it would be neat to talk them into testing kayaks “on a slow day”. Anyone have connections with the navy? They could test the relative resistance. Maybe they’d need multiple tests at 100lb, 150lb and 200lb “ballast”.
you boat what you got
I'm 80% whitewater so the other 20% suffers a bit when I venture out. Sometimes its just easier to rent a boat at a particular destination. My ww boats and crossover are also used quite a bit for flat meandering creeks, swamps, slow river paddling.
Occasionally I've found myself on lakes in my ww kayaks and wished I was in something more efficient. It's more about effort spent than speed for me. Paddling on the NFCT in the adirondacks in whitewater boats is an example of that. However I make the time up that I've lost on the lakes and save some effort by skipping some of the portages- so it kind of evens out there.
What was cool to me was when castoff let me try his ocean kayaks and how well they did in wind. We paddled and made headway on a day when I wouldn't have even thought about paddling my ww boats. I missed the initial stability of ww boats. Castoff's boats felt tippy to me so more seat time would be needed to feel more secure.
For me its more about exploring different environments- certain boats work better in certain situations but sometimes you can get by without having to buy or rent another boat as well. Not only can you adjust what boat you take out but you can also adjust your expectations- lower your mileage and speed when taking shorter boats on the flats.
here's what I've learned- rafts and duckies- you want current or you're just going to wear yourself out
old school ww boats like my perception mirage- have some speed but uncomfortable for paddling all day on the flats
cross over (ll xp) boat- room for an overnight, fully ww capable, not very fast or efficient in the flats but comfy seat, pretty versatile boat as advertised-but slow on the flats- it plows
rec canoe- pretty versatile, my particular model doesn't portage well or do extended trips- sometimes I use a canoe paddle and sometimes a kayak paddle- just depends-the canoe is the original "rec boat" and I've wrecked a few of 'em. You can definately cover some ground with a motivated tandem.
ww riverrunners, crossovers and creek boats work fine on twisty streams and swamp paddling and on ww- slow on the flats
coastal inlet paddling- learn how to run with the tides is as important as what boat you pick, I know what I don't know so I take small bites in that environment but have been using what I have
So for me the question isn't so much about speed or a tourer versus a rec boat but rather about effort and safety and what I own.
I did add a looksha sport to the fleet but haven't gotten it out yet so perhaps there's a glimmer of hope for me as a flatwater paddler.
Here’s a chart…
That may give you some insight as to speed and efficiency work out by the formulas.
http://www.pygmyboats.com/boat-kits.html
That chart is cool but…
How do they derive the number for Std Cruising Speed? Is a lower number or higher number better?
I’ll just be “cruising” (but pushing myself some) for my outings because I’ll be paddling for at least an hour straight. I’m thinking something around 14.5’ could be good
They do say this:
“**Efficient cruising is a function of low frictional drag and low wetted surface (WS). Lower WS means a faster (less effort) cruising speed, here expressed in sq. ft. For example, the shorter Arctic Tern 14 cruises with less effort than the longer AT-17 until the AT-14 reaches 4.91mph.”
anecdotal…
A friend’s small son was paddling his AT17 when I put him in my AT14. His first remark was that the 14 was a fast boat.
I’ve seen smaller racers do better in shorter more efficient boats. All depends on how much power the paddler has.
Rec boats could easily have less wetted
… surface than sea kayaks. The boat with the least wetted surface would be rounded on the bottom and just as wide as it is long. No kayak has such a shape, but wide short rec kayaks are a lot closer to that than long, skinny sea kayaks. As pointed out by Grayhawk below, shorter boats generally have less wetted surface than longer boats and move more easily through the water when at moderate speed, but they “max out” at slower speeds than longer boats. Complicating things even more, rec boats sometimes have complex hull shapes to provide rigidity, and that increases wetted surface area, and they often are blunt enough to plow through the water and kick up a big wave (wasting energy).
I think we’re all playing fast and loose
with what makes an object resist less. We know, for example, that drafting can decrease the effort needed to propel an object through water or air (for both the object in front, and the one drafting). Drafting is basically extending the length of an object.
Well, …
... I find that the idea that a shorter boat moves through the water with noticeably greater ease than a long boat holds true when comparing my two rowboats, in spite of the fact that the shorter boat has a little bit of reverse curvature inside of the chines which would increase wetted surface area by a little bit (apparently that small increase in surface area is not enough to matter much). In any case, the idea that a shorter boat has less wetted surface area than a longer boat is a geometrical certainty, as long as the boats are reasonably similar in shape. Also relating to points already made by grayhawk and his chart, the advantage of the shorter boat disappears as soon as you try to make real speed. The shorter boat "maxes out" at a slower speed than does the longer one. In fact, even before reaching that speed, there comes a point where the effort simply isn't worth it. I came up with the idea quite sometime back (based on effort, GPS speed readings and waterline length) that 3/4ths of a mile per hour slower than hull speed is a very practical limit for cruising speed (that's roughly the figure I used in my other post), so I found it interesting that this turned out to correlate so closely with the info in the chart provided by grayhawk (hull speed isn't included in the chart, but if you estimate waterline length based on the pictures and stated total length and calculate hull speed, their stated max cruising speed is really close to what I would have guessed).
The bit that I said about extreme increases in wetted surface area (due to the presence of very large ridges and channels down the length of the hull of many rec boats) and blunt bows which plow along making waves seems to make good sense, but more than that, I think everyone here has had the chance to notice that such boats are unusually slow, so I don't think it was too much of a stretch (playing fast and loose with the facts) to say as much.
Be all that as it may, the actual details behind this stuff, and the kinds of comparisons that would lead to more than just approximations, are beyond what most of us could ever understand or explain.
Oh, and you are right about drafting. With boats, you have to draft *really* close to get the full effect, and in that case you are turning two boats into a single, longer one (it helps to overlap the pointy ends of the two boats).
I find
that I can maintain a greater speed in my longer boat than in my shorter boat. So I guess we have a stalemate.
No stalemate
I started out that post pointing out that shorter boats with less wetted surface area move through the water with less effort at slow or moderate speeds (don't lose track of what was said in the post you initially replied to - that's where the distinction was made regarding what speeds this comparison applies to), but that has nothing whatsoever to do with the topic of maximum speed, which was the topic I switched to a few sentences later. If the only thing you want to focus on is maximum speed then you should just ignore boat comparisons having to do with slower speeds. The two topics are not the same. Of course longer boats have greater top speed, and that's exactly what I said in both of those posts.
That makes a comparison irrelevant two different
paddlers.
If my hull does 7 mph I sure as hell can’t cruise at 6.25 mph.
Hull speed is a measurable characteristic. This is not anecdotal stuff.
White water boats have allover lower hull speeds, for a good reason. Rec boats faster but not as fast as typical 16 to 17 ft sea kayak. Tacing tuned long boats like Epics fastest.
I have to disagree with this — hull speed as traditionally defined is a (too) simple parameter calculated based on water line length only. It does not taken into account any other hull shape parameters, and is not really a measurable quantity, per se. What you say about white water, rec boats and sea kayaks is all correct, of course, but the variation is not really captured by the calculated hull speed parameter.
Hull resistance increases with speed in a complicated way based on the different rates of increase of skin friction and wave-making resistance, which together sum to the total resistance.
Resistance curves are typically exponential; over a certain range of speeds the resistance will exhibit a more rapid increase. The calculated hull speed is usually within that range of speeds (not always). But there is no fixed and identifiable speed at which this happens, hull speed is just a general indicator, so is not really used in naval architecture nowadays. It is a decent way to compare similar hulls, but beyond that is not too useful quantitatively.
OPer asked if sea kayaks were faster than unnamed other category of boat, but it would be strange for someone coming from racing or WW boats to ask that. In both cases hull speed is an normal factor in talking about a boat. So they pretty much had to be referring to rec boats.
One factor is the minimum volume necessary to float a person. That is static and doesn’t change.
A short boat must be fatter than a long boat to meet that volume. That makes it plow through the water. It is especially true with current design ideas of wide shoulders and hips, so anyone will feel safe in them.
There are two hull types, planing and displacement, that makes comparison almost impossible.
Hull speed is defined by the point where the bow wave frequency is the same as the length of the boat. Though it was originally worked out for sailboats, it comes close in kayaks. The efficiency of the boat can make a select few go past hull speed with little extra effort.
Part of that efficiency is in the rigidity of the hull. Soft hulls are slower because of changes to the hull and interfering with the bow waves.
Comparing the speed of different boats is apples and oranges. At a few races people in plastic boats and occasionally Hobie pedal drive enter. Without exception they take longer to do a five mile race than a boat built for speed takes to do a ten mile race. It also takes much more effort for them to do that.