but does the drive system work as well as advertized?
April 03, 2013 at 8:00am
Deconstruction of the White Bread Marketing Kahuna:
Is it all just a mirage?
Is there a big Kahuna of mechanized watercraft? You bet there is and we all know of whom I speak - Hobie - synonymous with California Cool and the ubiquitous Hobie Cat. Honestly they deserve a free plug...
'Hobie Cat Company is the leading manufacturer of catamarans, sailboats, sit-on-top kayaks, fishing kayaks and float cats. Featuring the pedal-driven Hobie Mirage Kayaks, plus a full line of Hobie parts and accessories.'
Nice. Hobie and water go together like ham and cheese, but occasionally like bull and shit. So much for the free plug, lol. Now believe it or not I really do like Hobie. Mostly because of their free wheeling creativity and courage to think out-of-the-box. I think their Mirage Drive, aka Penguin Propellers, was and is a tour de force, as is their Twist n' Stow rudder. Great ideas and works-in-progress from a great company.
The Hobie franchise is a good one and it has been nurtured over years by a top flight marketing effort. As a result the Hobie paddle craft have developed a near cultlike following of chanting true believers - the Hobieholics. Good for them. But the rest of us - the majority of paddlers - retain open minds and suspect that when one encounters overly fervid and condescending superiority - either from the Hobieholics or their big Kahuna - that perhaps something is amiss.
The most convincing evidence of such is typically a manufacturer who makes a series of impressive claims - one after another - but without a shred of evidence. Compare to the many designers and manufacturers who proudly publish detailed specifications and performance data. Length, beam, and weight for starters - and much more - like waterline length (LWL), beam waterline (BWL), wetted surface area, draft, target displacement, sinkage, enclosed volume, lines (body plan), prismatic coefficient and, well, you get the idea.
They often also include performance data derived from KAPER revealing drag/speed predictions. Pick up any issue of Sea Kayaker and check out the two or three monthly reviews where such data is commonly published. Such openness leads to confidence. Lack of openness has exactly the opposite effect.
So let's deconstruct Hobie's Mirage Drive page, line by line:
Hobie begins with the usual marketing list of key features. My comment in italics...
* Revolutionary new propulsion system (agreed)
* Pedal driven (true)
* Adjustable mechanism accommodates a wide size range of pedalers (true)
* Durable construction of injection molded plastics, anodized aluminum, stainless steel fittings (debatable)
* Self-cleaning mechanism (resists wear from sand and other particles) (unverifiable)
* Easily removable for transport and storage (true)
So far so good. Fair game, good marketing - well done and effective. Hobie then provides a basic explanation of how the drive works.
'See how the MirageDrive 'sails' flex and take the shape of a propeller blade then reverse their shape on the opposite stroke. This sweeping action (versus a complete revolution as with a standard propeller) allows the MirageDrive to utilize large, powerful blades in a shallower configuration. You can also use very short strokes, with the blades against the hull, to propel the boat through shallow water.'
'The blades can be 'tucked up' against the hull for beach landings.'
'The MirageDrive is easily and quickly installed or removed, is lightweight, extremely durable, and fully adjustable to fit many sizes of pedalers.'
Fair game. Informative and descriptive, factual and effectively shows the versatility of the system. Good video included. The word 'powerful', without data, is introduced. The claim of 'durable' is repeated (certainly debatable given the record of breakdowns and continuing redesign). Hobie then lists 'benefits' of the Mirage drive...
'Benefits of the Hobie MirageDrive
The MirageDrive is simple and easy to use. Your feet rest naturally on the pedals and you pedal effortlessly similar to a bicycle. The larger muscles in our legs produce more powerful propulsion versus arms using a paddle. In addition, correct paddle usage requires training and practice. You also stay drier as pedaling eliminates drips that you get from using a paddle. The MirageDrive is quiet and creates no splash. The Hobie MirageDrive leaves your hands free for fishing, photography or holding a drink.'
Now things begin to get interesting. This is the essence of the Hobie pitch - 'simple and easy to use', 'similar to a bicycle' and using 'our legs' for 'more powerful propulsion'. Great! Hobie knows that most beginners are intimidated by kayaks and especially the notion of having to learn what seems a difficult skill - paddling.
Nope, no 'training and practice'. Hey 'you also stay drier' - wear a tuxedo and pedal to your wedding - you'll arrive dry, crisp and clean. They claim the drive is 'quiet' and creates no nasty 'splash'. A real limo with blacked out windows. Heck, it's even 'hands free' for fishing, holding or drink or signing thank you notes for your wedding gifts.
Still, fair game. We're still in the allowable and expected area of standard marketing hype. Of course kayaking is a watersport so the claims of staying drier are silly at best. There is certainly a contradiction between 'pedaling effortlessly' and using our legs for 'powerful propulsion'. Power = force = effort. No effort, no power. And what's 'quiet' in marketing or to the gullible neophyte is not at all quiet for the flats fisherman. Reports are sufficient and convincing that the Mirage drive will indeed spook fish on the flats.
But now let's get to the meat, er white bread. Now Hobie 'gets technical'. At last!
'Let's get technical...
The Hobie MirageDrive propels the boat easily and smoothly, and reaches hull speed with minimal effort. It also generates significant static thrust. In a 'tug-of-war' between a single Hobie Mirage and a tandem paddled kayak, the Hobie Mirage won hands-down (pun intended). Check out the video below!'
I love this one!
Marketing at its absolute best, er worst. Hobie tries to back this one up with a video pitting designer Greg Ketterman pedaling a Hobie single in a 'tug of war' against no less than world champs Greg Barton and Oscar Chalupsky of Epic (paddling a double)! Is this impressive or what! Simply brilliant.
Hobie tosses in their first technical term - 'static thrust' (without quantifying it). How much thrust? We'll never know, the big Kahuna ain't tellin.
The marketing claim is simple and powerful - if a (relative) weakling designer can prevail over two world championship paddlers, this Mirage drive must be one amazing device - powerful and effective. The neophyte now believes he's gonna fly over the water, leaving any ordinary paddler in the spray. And can do so 'effortlessly' with his powerful leg muscles!
This demo is a ripoff.
Static thrust is simply that - thrust from a standstill. In a tug of war what you really have is a series of consecutive 'strokes' each developing a certain level of thrust, or force. With the Mirage drive there is very little pause between what amounts to very short strokes. Compare to the paddler(s) whose strokes are necessarily longer, and with a greater pause between strokes.
This 'test' is intentionally set up in such a way as to favor the Mirage. It's an illusion of which Harry Houdini would be proud. This 'test/demo' denies the paddler(s) the opportunity to develop headway and momentum (glide) and takes advantage of the longer pause/stroke of paddling. It simply takes advantage of the longer pauses between paddling strokes - when the Mirage is pulling against...
Heck, if your opponent stops pulling, you can beat anybody. The Mirage has only a momentary advantage, but prevails because the opposing paddler(s) never get to move. Set this up as a drag race and the paddler(s) would take a quick lead after only a few strokes. Irrelvent to real world kayaking, misleading at best and really quite meaningless.
But would sure make a good bar bet.
Let's face it. None of us buy kayaks to tow anything much, and we certainly don't buy them to engage in tug of wars. Your three hundred pound buddy might well beat you in a tug of war, but not in the hundred yard dash. Meaningless.
A fairer comparison would be to one of the better prop driven HPB watercraft (Human Powered Boats). These boys are serious and some of them compete with and against Hobies. Their competitions are serious and well documented. Here's some typical results - out of 12 HPB's, most prop driven, one paddler and Hobie Mirage Tandem with two pedalers:
1. The Hobie placed 7th in the 100 meter sprint.
2. The Hobie was 5th in the slalom.
3. The Hobie finished 8th in the drag race.
4. The Hobie was 5th in the 2K criterium, and
5. The Hobie did not place in static thrust.
In a fair contest the Hobie - with two pedalers, yet - was eighth against singles in competition. In overall points the Hobie Mirage Tandem was 7th. Regarding static thrust, the leading prop craft produced 72 lb. Hobie won't reveal theirs. More 'technical' claims by Hobie:
Even we were surprised at the efficiency of the MirageDrive. In a test to compare the efficiency of the MirageDrive, we measured the heart rates of several kayakers at varying speeds in several paddled kayak models. In every case, the heart rate-or effort expended to maintain a particular speed-was three to ten percent less for pedaling versus paddling. Translation? The MirageDrive converts the effort of the human body into forward thrust more efficiently than a paddle!'
Now it's gettin deep and I don't mean sophisticated. Hobie makes an interesting claim, namely that the heart rate to maintain a particular speed is alleged to be 'three to ten percent less' for a Hobie when compared to 'several kayakers' at 'varying speeds' in 'several kayak models'.
No description of the methodology, or the kayakers or of their experience and paddling skills. What speeds? How measured? What kayak models? What were the heart rates? Condition of kayakers? Without any reference points, or any real description this amounts to nothing but empty claims. White bread with no meat.
Now that we are in the 'technical' section - the part that purports to back up the initial (and expected) marketing claims - we are owed real data and convincing explanations. It is presumptuous and condescending to back up a marketing claim with - just another unsubstantiated claim. Hobie says they 'were surprised at the efficiency of the Mirage drive'. The real surprise is that they just won't tell us how efficient it really is.
But the HPB boys will - and they provide the data. At 3.5 mph the Mirage drive was only 22% efficient (heart rate 107). The drive doesn't really get efficient until it reaches 5.3 mph at 46% (heart rate 132). Now when you realize that many prop driven HPB's approach efficiencies are closer to 70-80% efficient, it's no wonder that in fair, head to flipper competitions the Hobie sucks hind teat.
Not fair game. It gets worse when Hobie offers this obscure explanation of this 'surprising efficiency'.
'Allow us to explain.
The MirageDrive creates less turbulence in water. This becomes apparent when you compare the wake of a Hobie Mirage to the wake of a paddled kayak. With each stroke of the paddle, you'll see two vortices, or whirlpools, on the surface of the water. These vortices are connected underwater, and there is considerable energy in these rotating masses of water. There are vortices in the wake of the MirageDrive, but since the MirageDrive acts on a much larger volume of water, they are much smaller and therefore contain less energy. To create forward thrust on the water, a boat must move water backward. It can either move a little water quickly, or a lot of water slowly. The key to efficiency is to move a lot of water slowly with the least amount of turbulence. The volume of water that the MirageDrive acts upon is approximately proportionate to the area that the fins sweep in one cycle, or about 226 square inches. The volume of water that a paddle acts upon depends on the type of stroke. A basic stroke would act upon a volume of water proportionate to the area of the paddle, or about 90 square inches. This is just a fraction of the area 'swept out' by the MirageDrive, which explains the difference in efficiency.'
Whew! Now let me try to explain their explanation...
In a VERY roundabout way Hobie (simplistically) attempts to connect the 'whirlpools' you see behind a paddle with 'turbulence' and 'less energy' moving the kayak. They claim the Mirage whirlpools are smaller and that less energy is lost. Still with me? They build on this 'logic' with the idea that to move a kayak forward, you must 'move water backward' and further, that the idea is to 'move a lot of water slowly with the least amount of turbulence'. They then claim their drive 'moves' 226 sq in of water slowly, compared to a paddle which they claim moves only 90 sq in of water more quickly and with more turbulence.
Wow! More than twice as much water 'moved' and with less turbulence! Based on this outrageous explanation a Mirage drive oughta produce, what, maybe three times as much thrust as a paddle? Hardly.
This is just plain bull. Completely and utter cowpies.
First of all Hobie never, ever quantifies the amount of 'forward thrust' they claim, for either their drive or the paddle in question. That alone disqualifies this approach. Further the notion that to move a kayak forward you must 'move water backward' is simply naive and just not true.
It's not at all about how much water you 'move'; it's about the efficiency (or slippage) of the flipper or paddle. Speaking simplistically if the flipper is 22% efficient, only 49 of the 226 sq in claimed by Hobie are in play. Compare to say a good wing paddle, properly used, that develops 'lift' and actually moves forward (yes, forward) during the stroke, does not 'slip' at all, and allows much more force to be converted into forward thrust. Based on Hobie's faulty analogy all 90 sq in, 100%, would be in play to 'move water'.
In this analysis the wing paddle creates double the Mirage thrust. Who's right? However factual, without real data this alternative analysis too is just a claim.
Hobie's explanation is bizarre, unreproduceable, without any documentation, completely unreliable and unconvincing. No meat. And it gets (much) worse. Despite the fact that they have no real prop driven competition, a seemingly paranoid and defensive Hobie now attacks propellor driven craft with a vengence - with claim after unsubstantiated claim. Let's take em one at a time:
'Why not use a propeller?
Human-powered propeller drives are typically smaller and therefore less efficient. We compared the performance of the MirageDrive to a propeller drive, and found the MirageDrive to be faster and more efficient.'
No meat, just white bread claims. No data whatsoever. How small? How much less efficient? What comparison? How much faster? How much more efficient? With Mirage cruising efficiencies in the 20% range, and even average sized blades in the 70% range I'm finding this claim pretty hard to swallow.
'Studies on tuna and penguins show that oscillating foils such as the MirageDrive are more efficient than propellers. Oscillating foils can make use of vortices that are naturally shed from anything going through the water to offset the vortices that would normally be generated by fins. This equates to less turbulence in the water. '
Now we're getting ridiculous. I feel silly even addressing this one. Now you just might convince me - citing the studies of course - that live tuna and penquins are more efficient than props. But Hobie takes a huge and ridiculous leap - implying their amazing mechanical drive is indistinguishable from the fins of tuna or penguins! Please tell me you're not that stupid. Next thing you know the Hobies will be mating with em. Puuuuulease! How ridiculous.
Fact: in studies comparing drives and props (not penguins and props) the only published tests I've seen completely contradict this absurd correlation. Real world: Mirage efficiency = 22-46%, prop = 70-80%. Fair racing competition bears this out.
'The MirageDrive fins 'feather' into the flow when not pedaling and create very little drag; a propeller creates significant drag when it is not spinning. '
A forced and selective example. Props can be designed to feather or freewheel if desired. Heck they can even be made to turn in reverse (try that with your flippers). And some of you may be familiar with 'folding props' that fold back and become streamlined when not being spun. A perfect example of misdirection. Hobie cleverly states a propellor creates 'significant' drag when not spinning - thus implying that all props will stop spinning when you stop pedaling. Not true. Some do, some don't. And 'significant' is never quantified. White bread.
' The back-and-forth motion of the pedals provides a long, smooth stroke. Pedals that go in circles on a boat have a much different feel than pedals on a bike. On a boat, there are portions of a circular motion that are more difficult, so the cycle is not smooth. '
Another selective and misleading example. Many of the prop driven HPBs use a back and forth motion similar to the Hobie drive; most claim that a circular motion is more efficient. Hobie's claim that 'there are portions of a circular motion that are more difficult' so the 'cycle is not smooth' would be widely contradicted by most cyclists and HPB builders. Hobie fails to document their claims in any convincing way. White bread.
' The back-and-forth motion allows the pedals to be positioned much lower in the cockpit. '
See above. Let me say it again. Many HPB prop driven craft also use a similar back-and-forth motion, and can be so designed if height is all that important. Is it? Not documented. Hobie wants you to believe that all prop driven craft use circular and higher positioning, and further that this is a clear disadvantage. The former is false and there is no evidence for the latter beyond Hobie simply sez so. White bread.
' The MirageDrive allows any length of stroke desired, and performs well with both short and long strokes. '
Oh boy, and here we go yet again. See above. The Hobie motion and variable stroke can and is used by many prop craft. Other HPB designers claim this system is inefficient, choppy and uncomfortable. Performs well? How well? How do short and long strokes compare in terms of thrust? No meat, just white bread.
' The pedals easily adjust to accommodate different size pedalers. '
Ho hum, see above. Hobie is making the same point repeatedly with the hope that you will flipflop away with the hopefully indelible but false notions that (a) all prop drives use circular cranks and (b) that this is somehow a disadvantage. Apparently if Hobie sez it enuf, why it must be true. Let's not forget how different sized cyclists adapt - they just move the seat! How hard is that? Gimme a break. A non-issue, non-advantage and unrelated to props per se. White bread.
' The oscillating motion allows the use of a simple chain and cable system that is unaffected by sand and dirt, without the use of complicated seals. '
Another forced example. Hobie wants you to believe that all prop drives require 'complicated seals'. Just not so. Seals sometimes are used but they are hardly 'complicated' and are both reliable and effective. A non-issue and non-advantage. Simple and unaffected by sand and dirt? I won't bore you with the drive's reputation for breakdown, and need for repairs, adjustments and upgrades. No proof, just more white bread claims.
'The fins shed seaweed because they do not make a full rotation. '
An advantage? Maybe. Hobie wants you to believe that weeds are a problem, that all props are unprotected, and further that their drive always 'sheds seaweed'. Always? Really? Even Hobie doesn't believe this - check their own maintenance page:
'To keep your Mirage Drive in top condition, it is always good to take care of it after each use. Rinse the mechanism after each use to remove sand, seaweed, saltwater and any other water particles. Cable tension should be checked periodically or when it doesn't seem to be performing properly.'
C'mon guys, does it 'shed seaweed' or does it not? Unaffected by sand? A simple google reveals plenty of users havin problems with both. Truth: No drive, prop or rudder is immune to seaweed or sand. The anal retentive can mount simple, inexpensive and relatively effective weedguards - surfskis routinely use em to protect their full time rudders. And are weeds really a problem? And how bout Hobie's Twist n Stow rudder - does it shed weeds too? Or simply twist and stow em? Bottom line: just another unsubstantiated and silly marketing claim.
' The MirageDrive fins fold up next to the hull for beaching and in shallow water by simply putting one foot forward. '
Finally a possibly advantage, fairly stated. But this is not a criticism of props per se. And last...
' We are very honored that Popular Science Magazine selected the Mirage as one of the years best new inventions in 1998.'
So what? Three years later (in 2001) Popular Science also recognized the water cycles, 'Watercycling Into the Record Books', subtitled 'Breaking speed records with the hottest cyles on the water'. This article praised a prop craft that set a record of 104.6 miles in 24 hours, and another that crossed the Atlantic AND the Pacific (!).
Ya really wanna know what kind of craft dominate in extreme long distance races? Paddle powered. What happened to the durable, powerful, tug-o-war champs? Flippin and floppin up the rear.
I love interesting and creative design and accordingly I really do like and admire Hobie. Their Mirage drive and Twist n Stow rudder deserve our kudos. What I don't like is the big Kahuna and Hobieholic lionization of products that are neither more nor less than works-in-progress. As such both have checkered records in terms of breakdown and reliability.
There comes a time when a work needs to be complete, reliable and effective. That time has passed.
To me Hobie/Hobieholics come across as superior and condescending - overly sensitive, often defensive and highly critical of legitimate and valuable debate. Hobie suffers from claimitis and white bread syndrome. It's fine to make claims - we, and most manufacturers do.
Say what you will. But be prepared to back it up with real and accessible data and meaningful tests. We need meat with our Wonderbread.
If I were Hobie, and my claims were really true, I'll tell ya what I'd do. I'd enter every short and long distance race I could, especially against other HPB and prop driven watercraft. I'd prove just how fast my Wonderdrive is. I'd be sure to enter extreme long distance endurance events to finish first against 'ordinary' watercraft, and to prove just how durable my flappin flippers were. I'd devise fair tests and honest, meaningful comparisons.
Yup, and I'd shout out the results, make legitimate claims, back em up and publish the data - every single shred of it. Has Hobie done this? Nope. And where Hobie's have competed the results were less than convincing.
Pass the salami...