What's the fastest human powered watercraft?

Until recently I had assumed it to be a surf ski, but while paddling mine in a local lake, I happened to meet someone in a racing shell, heading in the same direction I was. Eager to get a closer look at this strange craft, I paddled as fast as I could to catch up to it. I was amazed that it took everything I had to close the relatively short distance between us! So, how fast can one of these things go with a well trained rower on board?

Try these guys. 21mph!



I know what you mean about the scull. I was side by side with an older gentleman who wasn't working hard at all. I was in my OC1. He could accelerate and then glide like crazy? I think the singles get well over 10mph.

Holy crap! I want one of those!!

I believe that in the world of Kayaks, surfskis are the fastest kayaks… and only when comparing downwind average speed (open ocean paddling). So, if you want to go fast in the middle of the ocean, go for a surfski.

On flat water, things are quite different: surfskis aren’t the fastest kayaks around.

When looking specifically at human powered crafts on water, I think the list would look something like this:

FLAT WATER
Hydrofoil Bike on water
Hydrofoil Kayak on water
Rowing shell
Flat water kayak
Surfski
Racing Stand Up Paddle board

OPEN OCEAN
Hydrofoil Bike on water
Hydrofoil SUP
Surfski
Racing Stand Up Paddle board
Rowing shell
(note that as far as I know, there hasn’t been much success with an hydrofoil kayak in open ocean)

I’d love to see average speeds on a 20k course for all the above – and it would be interesting to see it all on a single table.

Very interesting, Ludovic. A quick question about terminology: I've always assumed that surf skis were a type of kayak, but the local Stellar dealer insists that they're two entirely different kinds of watercraft, and that "kayak" refers only to a fully enclosed type of boat, not to one with an open cockpit. Is this just his interpretation, or is this a common distinction made by kayakers/surf skiers?

I'd be curious to know if there have been any tests done to determine which type of mechanical system is the most efficient when it comes to translating muscle power into propulsion. Rowing shells capitalize on the huge muscles in the legs and back to move the boat. Hydrofoil bikes utilize only the rider's legs, yet they apparently outperform shells. Part of that could be because the amount of power produced by pedaling benefits greatly from high rpm. For example, on my racing bike, I can produce close to 1300 max. watts by raising my cadence to just over 140 rpm. At a more typical cadence of 90 rpm, my max power output drops to 750-900 watts, depending on my energy level. Obviously no one can move a paddle or set of oars at anywhere near 140+ rpm, so their power output will be limited to whatever they can produce through brute strength alone. There is also going to be some loss in mechanical efficiency, because the linear back and forth movement forces the rower to fight against his own inertia on every stroke, whereas the circular movement involved in pedaling imposes no such toll. Interesting stuff to think about.

Aurelius:
Surfskis are part of the kayak family: this without a single doubt in mind. Just ask ACA (American Canoe Association) or the FFCK (French Federation of Canoes and Kayaks).

Fair to say that surfskis can do pretty much everything a kayak can do, and then excel in downwind. Traditional kayaks can pretty much do everything a surfski can do, and then excel in camping, and / or white water.

A downhill bike is still a bicycle, yet SO VERY DIFFERENT. It’s a specialized bike designed primarily for riding down super steep terrain. By the same token, a surfski is still a kayak, and you guessed it: SO VERY DIFFERENT. It’s specialized kayak primarily designed for riding super steep ocean swells.

Can we therefore say that a downhill bike isn’t a bike?
How could we possibly claim that a surfski isn’t a kayak?

Personally, I think the word “surfski” is the most confusing term we could have come up with to describe what we do. I wish so much that we just called it: OCEAN SKI – but that’s another question for another time. ahahahah

Calculating a craft’s efficiency cannot be easy. It may actually be very costly. A “solid” test would be to take a human on machine No. 1 to travel say 20k, and then take the same human on machine No. 2 to travel the same distance. Comparing the average speed may tell you a lot more information than 72% efficient.

Back in the days, we used to call bicycles the most efficient machines ever invented; there were claims that bikes were 72% efficient, while cars were only about 10% efficient.

I believe that different tests would yield different results on the exact numbers, but probably fair to say that bikes are still some of the most efficient machines out there.

photofr wrote: Aurelius:
Surfskis are part of the kayak family: this without a single doubt in mind. Just ask ACA (American Canoe Association) or the FFCK (French Federation of Canoes and Kayaks).

Did you know that the British refer to kayaks as canoes? I thought my British friends were confused about this, but when I showed them a picture of a kayak, they reaffirmed that these were called canoes in the UK. I had always assumed that what distinguished canoes from kayaks is the type of paddle each one uses; double bladed paddles being unique to kayaks.

Can we therefore say that a downhill bike isn’t a bike?
How could we possibly claim that a surfski isn’t a kayak?

That's one of those deep philosophical questions few are equipped to answer. This is the bike I ride:



While it matches the dictionary definition of a bicycle, most people wouldn't call it one. It's usually referred to as a "recumbent", and recumbent riders tend to take offense when someone refers to one as a bicycle!

Calculating a craft’s efficiency cannot be easy. It may actually be very costly. A “solid” test would be to take a human on machine No. 1 to travel say 20k, and then take the same human on machine No. 2 to travel the same distance. Comparing the average speed may tell you a lot more information than 72% efficient.

You could certainly do that, but it would be a mistake to use the same person to test all the machines. Because unless he happens to be equally proficient at cycling, kayaking, and rowing, he will not possess the skills or muscle development to provide an objective assessment of all these very different water craft. I think it wouldn't be all that difficult to come up with an objective test for efficiency, using test subjects who are experts at each one. All it would require is fitting each machine with a power meter, and then determining how much power it requires to keep each one moving at a given speed. That's how we can accurately compare the relative efficiency of my M5 racing recumbent (pictured above) to all kinds of different bicycles, irrespective of how different they are in design, or who rides them.

I feel that measuring watercraft efficiency isn't going to be an easy task. I keep telling people that the 560M is super fast, faster than most surfskis in sprints... people try it and agree that it "feels" faster... but it brings questions:

Where's the measuring tool for efficiency?
What is it called?
What does it do?
Does it take into account smaller or larger paddlers?

In the end, we could probably prove that a ski deemed "inefficient" could be faster in huge downwind conditions - even in the case where stability wouldn't be an issue.

photofr wrote: I feel that measuring watercraft efficiency isn't going to be an easy task. I keep telling people that the 560M is super fast, faster than most surfskis in sprints... people try it and agree that it "feels" faster... but it brings questions:

Where's the measuring tool for efficiency?
What is it called?
What does it do?

The tools you'll need are a power meter and a GPS (or speedometer). Used in conjunction, these will tell you exactly how much power is required to propel the craft at any given speed, which is the measure of its efficiency.

Does it take into account smaller or larger paddlers?

Not directly, although it's to be expected that larger paddlers will produce more power to offset their weight disadvantage.

In the end, we could probably prove that a ski deemed "inefficient" could be faster in huge downwind conditions - even in the case where stability wouldn't be an issue.

Lets not muddy the waters needlessly. I'm not comparing skis; I'm comparing the efficiency of the three basic methods of propulsion I listed.

You make measuring watercraft efficiency quite simple. I must ask: Why haven't I ever seen or heard about a single person measuring the efficiency of a surfski?

photofr wrote: You make measuring watercraft efficiency quite simple. I must ask: Why haven't I ever seen or heard about a single person measuring the efficiency of a surfski?

Surely you have heard of it. Wesley Echols' conducts these sort of tests, complete with GPS data to back up his findings. I'm sure you're familiar with his website and others like it.

To determine which human powered watercraft is fastest seems quite simple. To determine which watercraft is most efficient may turn out to be a whole lot harder - with or without a power meter. There are just so many variables to take into account. Coming up with an exact efficiency % for a given watercraft would be so interesting, but so far fetched: there are just so many variables involved.

I can give you couple of fun estimates, right off the bat:
1. A recumbent bike is super efficient, until you go uphill.
2. Me going downwind on a good day feels pretty darn efficient - gets me smiling from point A to point B.

Maybe all the high tech measuring tools can be replaced with the size of a smile for a given day on the water?!?

photofr wrote: To determine which human powered watercraft is fastest seems quite simple. To determine which watercraft is most efficient may turn out to be a whole lot harder - with or without a power meter. There are just so many variables to take into account. Coming up with an exact efficiency % for a given watercraft would be so interesting, but so far fetched: there are just so many variables involved.

For flat water, it shouldn't be that difficult. The engineers on the bentrider forum tell me that a propeller has proven to be by far the most efficient way to transfer power in watercraft, so that eliminates any type of paddle driven system from consideration. The compactness and adaptability of a propeller drive also allows it to work with practically any hull configuration. All that's left then, is to decide on the kind of hull. Since stability is paramount, a double pontoon arrangement is the logical candidate. Designs of this type have had a long and very successful record in racing, so there is no question about their inherent efficiency.

Once having determined the method of propulsion and the hull configuration, the question of which type of watercraft is the most efficient has already been answered; the rest is merely a matter of working out the details.

I have a concept design which solves two problems posed by a conventional propeller: the drag in the water created when the prop isn't spinning, and the bulk and complexity of a multi-gear drive. I think both problems can be solved rather elegantly by an array of spring loaded blades which open when turned, but retract automatically when not in use. Blade deployment is determined by the amount of force applied to the pedals. The more they open, the more force they generate, so unlike a conventional fixed blade prop, the "gear ratio" is determined by how hard the pilot pedals. That allows him to modulate the speed of the boat without large changes in pedal cadence, and with no need for gears.

no fans of towing tank tests here it seems ?

btw, for retractable blade propellers, you can omit the springs when turing the thing around ...
www.myboatsgear.com/library/resources262...od_2123_enlarged.jpg

I guess back in the days, we had tank tests. Today, I would see a drone far more appropriate to test for hull efficiency. Just a thought though.

yeah, but only with paddling motion to simulate the drag effects thereof,too lol

but beware, this would give numbers to marketing's "unbelievable fast"

Here's a link to a pedal driven kayak. Note the speed it's capable of:

www.elmtreedental.com/AR_Pedalkayak.html

The fastest human powered warercraft is Decavitator, designed at MIT. Record set October 27, 1991 on the Charles River in Boston, MA. 18.5 mph (21.3 knots)

That should be 18.5 knots (21.3 mph)

Single sculls aren't all that fast. I train on a river with a lot of rowing craft (Cambridge, UK). Mixed it up with a couple of sculls the other week, we were both doing intervals and I comfortably overtook them during the intervals. 

Rowing eights are considerably quicker than a K1 or K2.  you would expect them to be, the hull is very long.
[edit] I decided to look this up.
Rowers have short races, the standard international distance is 2000m. The larger boats also take a while to get up to speed.
Rowing 8 record for 2000m is 5min 18s. That is an average speed of 22.6kph. I think they were probably doing closer to 24kph at a guess. 
The K4 record for 1000m is 2min46s. Works out at 21.8kph. Again, I suspect that the top speed would have been quite a bit higher.