# for sea kayaks, how much speed difference between a fast and slow boat

In reviews of various boats, such as the ones in another section of paddling.com, the reviewer’s impression of the boat’s speed is usually mentioned. I currently own two boats: a composite Chatham 17 and a Sterling Grand Illusion. I don’t think of either as particularly fast or slow but I don’t have a great deal of experience in different boats. Averaged across different paddles, different types of strokes, different stroke cadences, I found the two boats to be remarkably similar (average of 4.3411 mph for the Chatham and 4.3353 for the GI, although I can drive the Chatham very briefly at a slightly higher unsustainable speed of 7.1 mph vs 6.0 for the GI. Anyway, when considering the merits of different boats, I just wonder how different a “fast boat” is from a “slow boat”. I 'm not talking about rec boats or specialty boats (like surf skis) but just the typical touring kayak. For some people (e.g., someone who likes to do group paddles but often finds themselves falling behind), maybe an extra 0.3 knots is worth it. For others, I would guess that the difference is small enough that it should probably take a backseat to other considerations. And not to go on, but obviously speed interacts with other variables. For example, a boat that is just sort of average in terms of speed on flat water might have a speed advantage in windy and/or wavy conditions due to superior handling characteristics in that environment. So I’m starting to wander but the main question I am hoping to have answered is how much speed difference separates fast from slow touring kayaks.

When they figure kayaks for racing classes there is a mathematical formula on kayak dimensions many times. When I raced offshore boats and one was 1/4 mph faster than the others after an hour one was 1/4 ahead. Made you ask when veiwing why did the other guy show up?.

Group paddles I have been on you’re only as fast as the slowest guy anyway and that’s usually slow. Groups I have been with never break 2.5 mph. All sea kayaks.

To me you have to be comfortable in a boat to go fast. My CD Nomad is usually generally speaking 1/2 mph faster when I am out cruising than my CD Solstice due to dimensions. Maximum top speed in flat water probably about the same .50 - .75 mph. You can feel the acceleration difference easily from a stand still. Nomad 18’10" x 21-1/4" vs. Solstice 17-6 x 24" or 25-1/4 I see it listed both ways.

“I am hoping to have answered is how much speed difference separates fast from slow touring kayaks.”

Depends on the “engine” !

Let’s complicate things. On flat water my 16+ foot boat has more glide (is faster) than my 14 foot boat. However, in wind and chop my 14 foot boat is significantly easier to turn and maneuver making it faster. Conditions count when it comes to speed or effort.

@JackL said:
Depends on the “engine” !

much agree

I have a couple ‘fast’ kayaks, and a few ‘slow’ kayaks, but, overall, they have roughly the same average speed (when ‘I’ paddle them).

## My ‘engine’ doesn’t have a lot of horsepower, but gets many miles to the gallon (can go a long way). (avg speed 4mph, even in a paddle around Cumberland Island (47mile) - avg 4mph) (note: I use overall avg, not moving avg)

for ref (current boats):
Epic V10 4.29 mph (total 2610 miles, mostly in 10mile trips)
18x 4.25 mph (total 4457 miles, mostly in 10mile trips)
Sterling Illusion 3.92 mph (total 3673 miles, avg 20mile trips)
Ice Kap 3.92 mph (total 9478 miles, mainly 10mile trip, though many other)
Progression 3.73 mph (1650 miles, avg affected by surf play use)
Tahe Greenland 2.98 mph (1038 miles) (avg brought down by many ‘rolling play’ sessions)

around Cumberland Island (47mile)
3.99 mph, 126 trips
St Johns daily (10mile)
3.97 mph, 2467 trips

(friends laugh at me for paddling the V10 so ‘slowly’)

note: recognize that if you ‘push’ a fast boat, it will perform better (faster) than same effort in a ‘slow’ boat.

Here’s one discussion that you may enjoy. It’s dangerous to generalize but it looks like half a knot is a lot.

In general longer boats have a higher theoretical top speed but they also need stronger paddlers that can “suck up” the extra skin friction and take advantage of the shape (so the slowest paddler in a group might need a smaller boat to help them keep up).

All I know is when I have a long ways to go against currents, waves and the wind, I want to be in my 19 footer (NC Expedition). But of all the boats I have paddled, for whatever reason, the CD Prana seems to be very quick. I would say the same of the new, revised Caribou.

It’s probably a matter of perception, but flat water doesn’t seem as fast as textured water.

Aspect ratio…water line length divided by water line width. Higher the number the (generally) faster boat .

@TomL said:
Here’s one discussion that you may enjoy. It’s dangerous to generalize but it looks like half a knot is a lot.

In general longer boats have a higher theoretical top speed but they also need stronger paddlers that can “suck up” the extra skin friction and take advantage of the shape (so the slowest paddler in a group might need a smaller boat to help them keep up).

Accurate and well said…

I think there is quite a noticeable difference in situations where you’re fighting current, or trying to sprint out through a surf zone to time breaking waves, or trying to catch rides on downwind runs, or catching any waves to ride. I think one of the ways to tell is just by paddling hard in two different boats. I can jump in my Tiderace Xtreme, or P&H Capella, or even my Current Designs Caribou, and speed my cadence to the point of a gurgling bow wake, and extreme resistance to speeding my cadence up further - meaning I’m rotating and pulling hard. If I go from something like the Tiderace Xtreme to the Current Designs Extreme/Nomad, the difference in a sprint - the speed of the cadence I’m able to crank out, is immediately obvious. At the cadence rate that the Tiderace Xtreme is hitting a wall, it still feels free and easy and ready for more in the Current Designs Extreme. Seems to fit the intentions of both given the Tiderace is a 17’ 0 " play design, and the Current Designs is an 18’ 10" fast expedition design. But yes, definitely, if you’re into good form and strong paddling, and you have the gusto to realize the limitations of a slower boat, then a faster boat will paddle easier… And at the ends of the sea kayak spectrum, like these two examples, at a 4.5 knot pace, which isn’t that fast, I can tell you that I’ll be working much harder to maintain the same cadence in the playboat. Now you start playing around in surf for several hours, where you’re regularly cranking out short sprints to punch out, or to catch rides in, and the difference between the Tiderace and even the P&H Capella become obvious, with the Capella feeling quicker, and the Tiderace Xtreme shining when the waves get really steep.
You can really get a feel for what it takes to pick up rides on following waves and swells if you use a kayak a lot. When you switch into something that just,can’t………quite…….grab those rides that you’ve become used to being able to ride along with in your other kayak, it’s noticeable and can feel quite frustrating.

Here’s the simple answer. Narrower, longer, lighter boats are faster. If you paddle for 2 miles in a standard sea layak it’s not a big deal because your body has plenty of energy but if you go out for a 20 mile paddle you’ll want a fast boat. I went from an HPK to an elite surfski. There is no comparison. I am much faster and way more efficient than in any other kayak I’ve ever paddled. If you are in good physical condition and want speed get yourself an elite surfski or K1. I’ll never go back (big plus is no one ever asks to borrow my boat).

I’m curious about skin friction. I have a roto-modeled kayak. It’s in good shape but the plastic develops little scratch. I wonder how that compares with smooth gelcoat over hard fiberglass which scratches a lot less with respect to drag. Is the guy next to me in a Cetus going to be able to go the same speed with 5-10% less effort compared to me in my Scorpio?

Apparently, the relationship between drag and surface texture/smoothness is not entirely intuitive.

from the first couple of sentences “…the skin of sharks has achieved a certain biomimetic status among both science popularizers and in research circles for the notion that the specialized skin surface structure could reduce drag and enhance the efficiency of locomotion. Manufactured body suits have been loosely modeled on shark skin with various ridges and dents, to induce surface roughness, that purportedly enhance swimming performance in humans, and researchers have long suspected that the special surface structure of shark skin contributes to the efficiency of locomotion.”

Maybe future kayaks will have faux denticles?

@l2t said:
I’m curious about skin friction. I have a roto-modeled kayak. It’s in good shape but the plastic develops little scratch. I wonder how that compares with smooth gelcoat over hard fiberglass which scratches a lot less with respect to drag. Is the guy next to me in a Cetus going to be able to go the same speed with 5-10% less effort compared to me in my Scorpio?

Slather any boat with fish slime and it will probably be faster for a few yards. I"ve used Rain-X on my boats and at least they feel a bit more slippery for a short while. I’ve got to find out what they put on my wife’s new car windshield. While driving in the rain, you don’t even need to use the wipers until it rains hard.

We use to fine sand the hulls of sailboats to take the gloss off and help the laminar flow over the hull. Doubt it would help that much at kayak speeds. We would never wax a hull.

I have a vague memory of reading that Greg Barton may have experimented with a hull micro texture on Olympic kayaks. Possibly it was banned?

Magooch is right that fish slime and other long-chain polymers released into the hull boundary layer can reduce drag - this was demonstrated in the 80s, the physics are somewhat complicated. However, it requires a continuous addition of the ‘solvent,’ which costs a lot, makes a mess and is probably disgusting - who wants a snail-trail of slime behind their boat? If this actually worked in the real world, I’m guessing we’d see slime-trails behind racing boats and attack submarines, but we don’t.

Re shark skin, the surface texture (fine grooves) can reduce drag a bit, but only if aligned properly with the flow, and over a narrow range of speeds. Swimmers move in a 3D, unsteady manner and the flow is effectively never aligned with the texture. It is my guess that the compliant nature of shark skin, i.e. the fact that it flexes underneath flow variations in the boundary layer is the more important effect. In my opinion, the grooved texture of shark skin may reduce drag by facilitating skin flexure, rather than by modifying near-wall turbulence structure. This is just my opinion, I have no evidence. It is true, however, that near-wall turbulence structure needs to be modified in a significant way to yield useful drag reduction.

On a related note, I perceive that my skin boat has less drag than my hard shell boat of the same size, possibly due to the skin flex. But maybe I only perceive that to be the case because it is quieter than a hard-shell boat and seems stealthy and, therefore, faster. I do not claim to be impartial since I made the boat myself 11 years ago and still find it delightful to paddle, although my legs fall asleep in it after an hour or so.

For swimmers wearing body suits modeled on shark skin, I’m guessing the primary effect is to compress the musculature of the swimmer and streamline the body. I believe this effect predominates over any marginal modification of near-wall turbulence. Insulation of the muscles may be a secondary effect by reducing heat loss while swimming. Any of this would be extremely difficult to prove scientifically, since swimmers are people and hard to measure while undertaking an unsteady, time-dependent activity.

Back to kayaks: at low to moderate speeds, most small scratches and other hull dings are effectively invisible to the flow, i.e. at low speeds an irregular surface can still be hydrodynamically smooth. It’s only when speeds increase that the hull boundary layer becomes thin enough that small surface imperfections intrude into the flow, modify the turbulence structure and cause drag. Fast sailboats and speedboats operate in this regime - having said that, fine sanding the gloss off a sailboat finish probably won’t do anything to influence the flow - this sounds like nonsense/voodoo to me. Waxing is also irrelevant - a hull that is smooth does not need any surface treatment to improve the flow: smooth is smooth, that’s all you need.

Overall, and in general, the smoother the hull the better - at low speeds, not very smooth will be smooth enough, so don’t worry about the small scratches. Experienced paddlers know this based on the feel of the boat, and that widespread perception is supported by the physics as far as I can determine.

Just the same, I will continue to keep my bottoms as clean and shiny as possible–just because.

Like a few others have said. On smooth glass like water its not a huge speed difference . Were I see a big difference is on small following waves (1 foot). I can just speed way ahead in my faster boat over my slower one.