Everyone seen this? Hobie mirage drive vs. paddle power.

That's interesting, and I also recently saw this post (with accompanying video) of a 2-man hobie beating some OC-1s www.hobie.com/au/en/forums/viewtopic.php?f=11&t=62004&p=296962  and video -

the post has details about everything they did to prepare the boat - plugging scupper holes, working on weight distribution, etc.

I'm curious if anyone has ever tried adding a mirage drive (or similar) to something like a surfski or k1 - obviously you'd still need the paddle for stability. Maybe it's not really possible, and it doesn't seem to make practical sense anyway - but an interesting thought.

This makes sense physics wise for a couple reasons that come to mind. One, your legs are the strongest muscle in your body, so the absolute power output potential of the pedal drive is probably greater than the torso/arms.

Second its hard to tell exactly how big the flippers are but to me it looks like, the small surface area of the flippers allow them to spool to a higher cadence, and their thrust-at-0-speed is much more "torquey" than a wing blade. In my experience, a wing blade is very un-fluid at 0 speed and really needs forward speed to 'fly' through the water and perform optimally.

So to me it makes perfect sense a pedal drive would win a 0 speed tug of war. Now I'd like to see a comparison of a pedal drive accelerating onto an 8+mph ocean swell vs GB on a ski. That would more accurately compare a SS on its home turf

How sustainable is this rate of pedalling over anything longer than a tug of war?

Mirage drive is really cool. It allows people (mostly kayak fisherman it seems) to move a slow heavy wide short rotomolded boat way faster and way further than they could if they were using a paddle. In their current application the speed is limited by the hulls. Motivated guys get those barge like fishing kayaks up to 6 mph and hold them there a long time. I see no reason why the same gain in efficiency over paddling would not be found if the system could be installed in a fast long light skinny hull.

I am not aware of any creature in nature that paddles along plunging something in and out of the water with each stroke. Nature abounds by contrast with flippers. I suspect that is because they are efficient. The mirage drive reminds me most of the way penguins "fly" under water. Penguins obviously go fast enough to launch themselves out of the water and up onto fairly tall ice bergs. 

Regarding the tug of war test, that is probably the situation in which a paddle is least efficient, because there is no way to lock the blade on the water. Rather, the boat is locked in place and the paddle moves backwards introducing huge amounts of air cavitation and turbulence. In addition, hull speed has no effect on tug of war as the boats are not moving, negating much of the advantage of a racing kayak. 

Sometimes it is tempting to think that surfski is the coolest paddle craft out there, but that is not the case. There are so many different types of craft, all designed for a purpose. They are all the coolest at what they do best. Rowing skulls are faster on the flat, rotomolded SOTs are better for fishing, sea kayaks are better at expeditions, open canoes are better for camping trips, surfboards are way better at beach waves, etc. We don't even own the title of fastest down wind craft anymore, as SUP foil has stolen that distinction in just a few short years since it's invention. 

Interesting stuff! I wonder how the glide is with that mirage drive, e.g., when accelerating down a wave. If it glides well (i.e., doesn't introduce a ton of drag) I'd be tempted to see whether I can mount it on my Nelo 510. That should be stable enough not to fall in (may need a small paddle for bracing anyway?) and might make it a very fast boat in the flat... Plus it would be cool to be able to do leg exercise sessions in addition to just core body exercise sessions (yes, I know the legs do a little bit of work in the rotation).

I did a quick search and it looks like it's actually been attempted once news.fasterfarther.com/custom-surfskis/2...drive-hybrid-surfski although there's no info beyond the CAD images - I wonder if it ever got made and tested.

My wife and I had a tandem Hobie Mirage Drive kayak a few years ago. The hull was a pig, but the drive unit was pretty interesting. Lots of thrust down low; it would really move out off the line. We could get that boat up to 6 mph, but it was tough to hold at speed. I'm an avid cyclist, but the back-and-forth motion and the angle of the seat wasn't the most comfortable. I always thought it would be fun to try in an OC1 or similar. 

Having pedalled and paddled their skinniest kayak for many years, they are a barge by ski comparisons, the main difference is low down pulling power. Load one of these up with lots of heavy gear and it is not as affected as a paddle craft. Yes the legs are a strong muscle group, but that is all you are using, no core muscles, and practically no technique.  As far as fitting one of these drives to a ski or similar, apart from the the engineering issue of a big hole in the middle of your boat with a lot of concentrated stress around it, you have no balance or bracing.  kayaking while effectively sitting on your hands is just unnatural. Hence a pedal craft needs to be wide as it relies heavily on primary stability. The drive itself is no lightweight mechanism either

As far as surfing/riding waves, you simply can 't do it once the boat tries to pick up speed faster than you are pedalling the fins start to act as brakes, throwing you into broach, with no paddle to brace. Hence they can be deadly in large following seas as the only steering you have is a rudder hanging off the back, and when that lifts out of the water you are stuffed with no means of control.

They are great for the hands free functionality of hands free fishing and hauling gear, but as a sports craft they are just plain cumbersome. Hobies fastest one is between 40-50kg unlaiden. Load them up with fishing gear and some of these outfits can be heading towards 70kg before you have even put your bum on it

5 years ago we did an 80 mile non-stop crossing the English Channel at it's the widest point. I was on an Epic V8, 3 others were on Epic V6s. The 5th member was a kayak fisherman who insisted on using the Hobbie with mirage drive. We trained for the event on the mainland. Mark trained with the Hobbie on the destination Island of Alderney. 

Mark trained for a year on the water and in the gym and was superfit. To hit the tidal plan we had to maintain a certain speed of 4.6 knots with no tidal assistance. Mark was convinced he could do this until we finally met for a group paddle. He revealed that due to the physical effort on his legs he would have to peddle and paddle alternatively each hour. Mark was very strong, but have you ever tried paddling the wide Hobbie? This forced us to add 3 hours to our original plan. At top speed, Mark could not stay with us even peddling for more than a couple of minutes. Another important consideration is that a paddle is what enables a kayak to stay upright in big seas. The brace IS the essential stroke. With the Hobbie, your hands are occupied for steering, therefore, no brace in big seas. 

Having said this. A very experienced sea kayak group did not make it across on the same night due to conditions leading to tiredness. Mark did very well to make it across on the Hobbie. The record still stands. Maybe another crack on just skis is due to knock off those 3 hours. 

Selkie wrote: 5 years ago we did an 80 mile non-stop crossing the English Channel at it's the widest point. I was on an Epic V8, 3 others were on Epic V6s. The 5th member was a kayak fisherman who insisted on using the Hobbie with mirage drive. We trained for the event on the mainland. Mark trained with the Hobbie on the destination Island of Alderney. 

Mark trained for a year on the water and in the gym and was superfit. To hit the tidal plan we had to maintain a certain speed of 4.6 knots with no tidal assistance. Mark was convinced he could do this until we finally met for a group paddle. He revealed that due to the physical effort on his legs he would have to peddle and paddle alternatively each hour. Mark was very strong, but have you ever tried paddling the wide Hobbie? This forced us to add 3 hours to our original plan. At top speed, Mark could not stay with us even peddling for more than a couple of minutes. Another important consideration is that a paddle is what enables a kayak to stay upright in big seas. The brace IS the essential stroke. With the Hobbie, your hands are occupied for steering, therefore, no brace in big seas. 

Having said this. A very experienced sea kayak group did not make it across on the same night due to conditions leading to tiredness. Mark did very well to make it across on the Hobbie. The record still stands. Maybe another crack on just skis is due to knock off those 3 hours. 

Sounds right to me. I assume it was an adventure 16/revo 16.  To effectively paddle one it needs to be adapted with decent foot braces, probably also  some effective means of helping it track. Once adapted thus I can fast cruise it longer than I can pedal it, as proper paddling utilizes the whole body, but pedalling puts all the stress on the legs with no pause or respite (no glide or wave surfing). Either way top cruise speed is less than even a basic ski, but maybe close to a sea kayak into a headwind, and maybe slower in following seas. Thats regardless of fitness as you hit a wall with hull resistance.

Did he have any contingencies for the mirage drive failing while half way across? Thats one of the issues of being way offshore with mechanical devices

Each hour we stopped for 5 min. He would remove the leg drive and set up for paddling. I will highlight again that he was very fit. He found paddling the Hobbie more tiring and considerably slower than peddling.

I doubt very much that this Hobbie would stay with a sea kayak paddler over distance. As an ex boat designer, it is obvious that this is not designed for efficient paddling. The weight and hull resistance is considerable. Sometimes kayak fishing friends kid themselves about their chosen craft. I have one such friend who believes his Tarpon 16 is every bit as fast as a sea kayak based on bimbling along on an occasional sightseeing trip. Let's be honest, most sea kayakers don't really push their craft along. They are out touring and sightseeing. I do the same on my V8 and V6. But when needs must or I chose to...I can kick it and there is no way the plastic fantastic is going to keep up