another speed question?

Ok so just to make sure I’ve got this right.

two boats, same hull design, chine etc…

one is 10foot 28" wide 40lbs

other is 14 foot 28" wide 59lbs

the 14 footer will be faster, correct?

Faster than what?
1. They are not the same design, and would handle quite differently.

2. “Speed” also depends on power.

It’s all relative. I’d consider either spec to be a really slow kayak. Enough so that it’s kind of funny to even be talking about “speed”.

If you go 3 knots or less it hardly matters. The shorter has much less surface area and may technically be easier to paddle at this speed (which is definitely NOT fast) - and the numbers would show this - but anything’s pretty easy at 3 knots and actual power required is pretty small. Differences tend to matter more over 4 knots (and that requires being able to comfortably cruise at the higher speeds to take advantage of those differences), and neither would be good for that.

Not helpful, I know. But then (as someone else here is fond of pointing out) neither is comparing minivan speeds.

Assuming same cross section
the longer boat has higher potential speed via reduced residual(wave-making) resistance. This means it creates a wave of translation at a higher speed, or can be pushed faster before hitting this “wall” that often is referred to as “hull speed”. At 2-3 knots it likely would test no more efficient than the 10 ft. version.

Soooo, if you are not a strong paddler and have no need to go faster, the shorter version of the hull may be fine. At lower speeds the drag differences are minimal and typically less with a shorter hull.

But, as speeds increase beyond the sweet spot for the shorter version, the longer version becomes more efficient. So, this can be confusing for sure, and it all depends on your power supply, and the speed at which you wish to travel.

Little, low powered folk tend to “net” better speed in touring boats in the 14-16 ft. range up to 22" wide. An 18 ft. version of the same hull would be too much, whereas a ten foot version might be too limiting. Having the ability to sprint a hull is important…so long as it’s not too much hull for the engine.

Touring boats like the Mariner Coaster, Impex Mystic, Necky Eliza , P&H Vela, Fosters Rumour, etc., (there are more) are excellent balances of variables for smaller paddlers.

I think it was Winters who said “The question is not which boat is the fastest, rather which boat is the fastest for a given speed regimen”

Going on memory there, so not sure… As in most things this comes down to “balance”. Too short is limiting, too long can also be limiting. Beware the absolutists.

One Example…
One day a friend’s 9yo son switched from his dad’s 17’ Arctic Tern to my Arctic Tern 14".

The 17’ is considered the faster boat. After two minutes in the 14 he exclaimed “Now this is a fast boat”.

A lot depends on the engine.

There are so many variables
And they all interact with each other.

Waterline length


length/beam ratio


hull design - many, many variables here

Does it have a fine bow? Is the bow fine at the waterline and then flare up to a wider beam? Does it hold the fine bow a ways back on the boat? Same thing with the stern. Rounded bottom? V-hull? V-hull morphing into a rounded bottom? Where does this change occur? Hard chines? How “hard” are they?

Speed vs efficiency?

Speed vs efficiency in flatwater

Speed vs efficiency in rough water. How rough?

There really is no simple, one or two variable answer.

Rumor and Salty’s comments
My wife is 5’ 1" and 110#. For her the Rumor is a rocketship and she easily maintains a faster pace than most group paddles and can out sprint many. In a bigger boat, she would just get bogged down. As Salty said, need to match the boat to the engine and expected use as opposed to blindly following some concept such as longer is faster.

I thought we had this hashed-out already
There are lots of correct responses here, but I take exception to the statements that because a longer boat with the same profile as a shorter one will sit higher in the water, it will not take any appreciable extra effort to paddle. My own experience (and those of numerous others, based on all the posts I’ve seen regarding this), is that the shorter boat WILL be decidedly easier to paddle at speeds below the point where it starts to “hit that wall” (approaching hull speed). Anyway, it’s true that a longer boat will sit higher and present a smaller cross-sectional area within the water, but the wetted surface area of the longer boat will still be greater since that boat deviates to a greater extent from a shape having the most volume per unit of surface area (a sphere, or since we are talking about only a portion of the object’s overall surface, a hemisphere) than the shorter boat does, and wetted surface area seems to be the factor having the most effect on paddling effort at speeds significantly slower than hull speed.

In comparing my 12-foot rowboat to my 15-footer, the 12-footer moves along at speeds of 4.5 mph or less with considerably greater ease than the 15-footer. The overall profile of the two boats is pretty similar, but the 12-footer has hard chines which present more edges and create greater turbulence than the very rounded profile of the longer boat. In spite of that, the shorter boat moves almost effortlessly compared to the longer one, as long as I don’t try to go faster than 4.5 mph. The longer boat is much faster, and is always my choice if I need to cover a lot of distance, but the effort required to make it go at any speed is a lot greater than the effort needed to make the shorter boat go at moderate speed.

I’ve seen a few on-line articles (that seemed pretty reputable) describing this exact line of reasoning, but unfortunately, I don’t remember how to find any of them.

More thoughts
I think just as many assume longer is always faster, it’s also incorrect to say that at touring speeds effort is much greater. It isn’t! In most cases the shorter boat does require less effort at slower speeds, but more is made of this that is fair. Actual data show the drag numbers to be quite close below about 4 kn.

Now, having said that, my take is simply that the longer boat doesn’t offer any “advantage” to the weaker paddler, and in fact probably causes them to work a bit harder (a bit).

Where the added length hurts is in WIND and bigger seas. The little, low powered paddler has a hell of a time controlling that big lever arm. This is where the smaller folk are really hampered by a boat that is too big. If conditions were always flat with no wind, it wouldn’t matter as much.

Lighter paddlers also may not displace enough of a longer hull to optimize it’s directional stability. Design Displacement is important in making a boat function the way it was meant. Too much displacement, and you lose handling, too little, and you’re a hocky puck on the water.

But almost nobody tells you
" Design Displacement is important in making a boat function the way it was meant. "

I believe this is quite true and imp0rtant for an informed consumer decision Which raises the question; “Why oh why are the only people who take even a stab at proving consumers this important data point those who sell kits/plans for kayaks?” It is amazing how much design data you can get for boats designed by say Nick Schade as opposed to any boat from a major supplier of composite boats. Surely they know what the numbers are, but they never disclose them.


– Last Updated: Oct-19-07 11:05 PM EST –

I did post that a longer boat will sit higher in the water, but I didn't say anything about effort. I agree with the post by guideboatguy in just about every respect. And I put it into practice by paddling a 13'9" sea kayak (sof Coaster), which feels as though it has quite low drag and consequently very snappy acceleration. And it is obviously very maneuverable due to its short length. Many better paddlers than myself have borrowed it and most remark on how easy it is to keep up with big sea kayaks on the Hudson River and LI Sound. I still wonder if I want a long sea kayak (I'm tempted by the Mariner Max), but I think first I should try to find the limits of the shorter boat. Plus it only weighs 33 pounds, so is really easy to launch.

The point made just above about design displacement is on point and I agree whole-heartedly. Why not give us the info so we can make an educated decision?

SOF Coaster
That must be a nice boat! I think manufacturers often list weight ranges, but to be fair, there’s a lot of subjective area here. At 210 lbs. i did month long trips in a Romany. Was it overloaded? Yeah. Did it do fine? Yeah. It was not as maneuverable when loaded, but still performed well enough. Same with your Coaster. Matt and Cam would likely say it’s not designed for a 210lb. guy with gear, but it worked well for me. So, I don’t blame manufacturers for not wanting to get cornered. There’s a lot not disclosed and my guess is the market wouldn’t grasp too much tech talk anyway.

It’s hard to overload a kayak. They just lose playfullness typically. For me, I’d rather paddle an over loaded Romany for example than an Explorer…but that’s just me.

you may be right
you may be right about tech talk - probably just one more spec to blow smoke about. And yes, the Coaster is a sweet ride - it never feels like it’s too small (I’m 5’9" 200 plus or minus), although I just do day paddles. A friend who is over 6’ took one on a 6-day river trip and it worked fine. Here’s my baby:

That’s Brian in it, he adapted the design to SOF.

Forget the numbers. Just paddle :slight_smile:
Though I appreciate the concept of understanding this and that about hydrodynamics and boat design, and I suppose I can be glad that boat designers are concerned with this stuff, at the end of the day, choosing a boat to paddle–especially when it comes to commercially mass produced boats–is perhaps even more an emotional, intuitive art than a science. Without even being a technically proficient boat designer (with regards to “the numbers”), I’ve paddled enough boats over the years to be able to look at a hull, and guess pretty accurately how it’ll handle on the water, and in various conditions.

I remember every boat I’ve paddled, and I remember every time when I first sat in a boat, paddled a few strokes, and felt that “Ah, this feels right” feeling. Do you think I cared even a little bit about the numbers at those moments? I can certainly know, without a doubt, if a boat will work for me by simply paddling it in various conditions; never once thinking about hull displacement, righting moment, theoretical max hull speed, etc.

In any event, I doubt I’d ever let “the numbers” convince me to have second thoughts about a boat that I love to paddle…would you? Of course, I don’t care about racing, so when it comes to speed and handling, I just want something that will allow me to safely and happily move around in the wind, waves, and currents that I encounter. I’m still alive and happy, so I suppose my non-scientific approach to boat selection is working well enough. :slight_smile:


A better approach

– Last Updated: Oct-20-07 9:27 AM EST –

may be "forget the marketing, and mis-information that prevents folk from experiencing what you describe" The numbers and hydrodynamics are not the enemy.

I think Melissa you represent most sea kayakers from the standpoint of gut feel, etc., over strict science / facts. I agree with that "gut" approach so long as folk aren't ignoring facts. People confirm their biases in all sorts of ways. Consideration of sound science can only help direct consumers to products that match their needs.

You’ve made some really good points here and above (and there are gems amoungst your many other posts). I really liked the 3hp motor analogy - no different than a kayak motor. An underpowered kayak motor (e.g. smaller person paddling a boat too large for them or an inefficient paddler) is going to work much harder and probably can’t approach the efficiency designed into the hull.

It is so important to paddle a kayak that works for you (i.e. for your size and your strength) notwithstanding your ability to (with hard work) improve your paddling efficiency. You’re efficiency will only improve to a point, then will hit a wall if the kayak is under or oversized.

This is one of the reasons we stress to demo boats - in all conditions you intend to paddle in - if you can. This is not always possible as we know, and is likely a major factor in why we change boats as our skills improve. Another significant factor is the flash of owning something new or different. A third factor is keeping up with the Wilsoj’s and Celia’s. If, for instance, they happen to add a new boat to their fleet, such as a Nordkapp LV, then I start to worry that they are approaching the number of boats I have in my fleet, so I go out and find something else to purchase. I doesn’t really matter how many you own as long as you have one more than they do. :slight_smile:

Of course, if you’re just interested in burning calories and don’t care about covering long distance or keeping up with other paddlers, then an over or under sized kayak might be just right!

One question I have is how does the same designer design a series of boats to fit large and small paddlers? It must be difficult and to some extent can must be based on best informed guess. If you are a 6’ tall, 185lb designer how do you design a boat for a 5’2", 100 lb. person? You’re own personal exerience in the prototype won’t help much. Maybe this is why we see a lot of low volume kayak designations that really only have a lowered deck and/or smaller cockpit. People need to understand that in many cases low volume usually means lower volume, maybe less impact from wind and less storage space, but the hull really hasn’t changed. This does not necessarily mean it will be good for a smaller person.


Correct wetzool…
Simply lowering a deck can make for a better small person fit, and less windage, but the design displacement doesn’t change, therefore, what didn’t work hull wise for the small paddler, still doesn’t.

Good designers know this and when making a boat for a smaller, lighter, paddler, design from the start against that objective. Computer modelling also helps tremendously as a hull can be shrunk / manipulated, hydrostatics calced etc., then plug cut on a CNC machine.

Hand tweaking by superb shapers makes the difference as well. The computer can do a lot, but cannot account for all variables…thus lots of testing, hand tweaking, before final plug is done.

Take care…