Strider

A dual Mirage drive powered, two person launch

Sometime back, I encountered an ex-pat American, now living in Melbourne, Australia, by the name of Mack Horton. Mack wanted to build a two-person boat for cruising the harbor and waterways of his hometown, Melbourne. He was looking to propel his boat with a twin setup of the wonderfully innovative Hobie Mirage drive designed by Greg Ketterman. I really liked that idea as I had already done a few different boats that were Mirage capable, but they were all solo boats. This design concept opened a new door for me, as it would allow me work out the balance and weight issues for a twin drive and once built, I could also discover how much more speed potential might be available beyond a solo drive.

I had a hull in mind from my portfolio that would need to be “massaged” just a bit to get the form stability and low speed performance for which I was looking. The boat had to be able to handle potentially large boat wakes and small chop in the more open regions of the harbor and still be easily driven by human leg power.

I was looking to achieve some of the lines of a classic launch with reasonably low windage and yet, enough freeboard to ward off the possible conditions. Surprisingly, the hull form came directly from a previous boat shown here at Duckworks, the A18, canoe/trimaran. The A18 hull had a very strong bias towards higher speed potential with only a nod to being driven at slower speeds, so a slimming process had to take place in the forward and aft sections of the hull. Likewise, the beam of the hull was pulled out some to give the boat a solid degree of form stability so it could ride the wakes of passing freighters in the harbor when taken abeam.
I sent the plans off to Mack and he promptly got to work on the boat at his favorite spot for boatbuilding, the Melbourne, Wooden Boat Centre http://www.woodenboatcentre.com.au/index.htm

 

 
Cut to the Chase

 

 

 

 

 

Mack has now finished the boat and has had it out on many outings. He’s learning a lot about boat trim and optimal placement of the heavier pedaler for best performance and handling. Besides the still photos showing the boat on the water, Mack has also provided a pair of video clips showing the boat underway.

http://www.youtube.com/watch?v=42YYFVYU720  

http://www.youtube.com/watch?v=f1xa4ZG-5AM&NR=1

Clearly, Mack’s Strider, Ripple, is showing itself to be a pretty fast boat when being propelled by two average people. This is being done from a semi-reclining position with hands free, while enjoying the sights in the Melbourne harbor and adjacent waterways.

Mack reports that one of the ubiquitous dinner cruise boats, that you see in just about every harbor of the world these days, pulled alongside and challenged both he and his friend, Justine, to a little race. Off they went with Ripple easily leaving the cruise boat in the dust. Later, as shown in the video clip, Mack and Justine took-on a fully crewed Dragon boat. Dragon boats measure 40 feet in length, 4 feet in width, and carry 20 paddlers, 1 drummer, and 1 steersperson. On average, these boats weigh 500 pounds. Understandably, Ripple could not quite match the speed of the Dragon boat with twice the waterline length and 20 paddlers. Perhaps there could be a triple version of the Strider in the future? One that is longer, more slender and much, much faster.The Strider design calls for a very straight forward stitch and glue build method in 4mm marine plywood with glass/epoxy laminates inside and out. The twin Mirage trunks sit cleanly in the hull allowing for a comfortable seating arrangement for two persons and their day pedaling “stuff” such as binoculars, cameras, food, drink, blankets, etc.
In the right environment, the boat could easily be used for overnight camping as well, as there is plenty of displacement capacity for more gear, should the owners wish to use their boat in that fashion.
I expect to see these boats being equipped with Bimini covers and small forward dodgers. The interior hull sides will probably be lined with neat rows of mesh bags to storage of the small things that make for a really nice time on the water, such as: sunscreen, lip balm, mosquito repellant, drinking water, snacks, camera, VHF radio, GPS, etc.
Maybe you have a cabin/cottage on a lake where the general store is across the water, but a short distance, but to walk, it would take an hour to get there. Strider is an excellent, human powered boat for a trip like that. An enterprising person could equip her with an all weather set of side panels to mount under the Bimini edges, allowing trips to the market in any conditions, short of a full-on gale.
The boat is car-toppable, much like a large canoe would be, but I’d advise the person doing the loading be reasonably fit and/or have a really sweet loading system or technique as the boat does weigh right around 90 pounds without the Mirage drives in place.
Mack has kindly supplied some very interesting speed marks for the boat that were confirmed with a Garmin Edge 305 GPS with wireless heart rate and cadence monitors.
Highest speed attained with two pedalers…… 7.2 knots
Highest speed with one pedaler………………… 5.7 knots
Average speed for one hour w/ two………….. 4.8 knots
Average speed for two hours w/ one…………. 3.9 knots
Turning circle for the Strider is 33’

These figures run pretty much spot on with my estimations. They also indicate that the hull has gotten to its, “not gonna go there” speed limit and will be pushing uphill on its bow wave from that point on.

Mack has a fun grouping of comments to go with his recent experiences with his new boat.

While underway in Strider #1, “Ripple”, it is not unusual to be hailed from dockside and be asked, “What is it?”, “How does it work?”, “How much does it cost?”, and his favorite… “It looks like it has an engine!”

 

Response has been very positive from athletes, because it’s fast… from non-water type folks because Strider is stable, comfortable, dry and “not scary”.

 

One of the reasons that Strider is so stable is due to the recreationally respectful beam of the hull. I’m working on a much faster version of the Strider design concept, which should pretty much take the Mirage drive out to its theoretical top speed limit. If Strider were to be prop driven instead, it could go even faster as props are more efficient than are the flapping blades of the Mirage. Unfortunately, most prop systems are quite a bit more expensive than is the Mirage, so the decision was made to go for a reasonably fast boat that was much more affordable overall.

 

All in all, Strider is a really fun and stable human powered vessel designed for recreational pursuits by two people. It has the classic look and feel of a traditional launch to it while underway and can easily power-up to get out of the way of oncoming traffic in a crowded harbor, or lake setting.

 Chris Ostlind

Lunada Design

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Posted: December 23rd, 2008 under Human Powered Vessel, Mirage Drive.
Comments: 1

Comments

Comment from Bill Genevro
Time: July 7, 2009, 1:30 pm

Mr. Ostlind,

Just a short note to tell you that I mentioned your designs to one of the editorial staff at Wooden Boat magazine today as an example of progressive wood boat design that should be appearing in their publication. I had called about another design and in the resulting discussion we agreed there needs to be more representation of the SW part of the country. Karen at WB agreed and asked for an example and I gave your designs. After I finish the restoration of a small cold molded tri I want to build one of you designs. Would you ever consider offereing builder’s camps?

Regards, Bill

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