We've Seen Catamaran SUPs, How About a Single Outrigger SUP?

[ericjayowsley]

I've been drooling over some OC-1 canoes of late, and the thought occurred to me: what about applying the single outrigger concept to a paddleboard? The board itself could be made narrower and take the displacement hull form further by making the bottom more rounded, since the levered weight of the outrigger and its buoyancy would help with stabilization. Additionally, I thought that perhaps the minimal drag of the outrigger might be just enough to counteract the tendency to push the board away from the paddle side, allowing the paddler to stroke longer and harder on one side without needing to change sides as often. I could see it being lighter and more nimble than the new breed of standamarans, and perhaps able to surf downwind without breaching in the manner of OC-1 canoes or surfskis.

Please tell me why this a bad idea. I'm about to start playing with it in earnest. Save me from myself if I'm missing the obvious.

[headmount]

Have only just recently tried an OC-2 but can tell the biggest challenge is how to turn towards the direction of the ama.   This mobility factor is also the biggest advantage of being on a SUP over an OC.  THe OC of course outperforms because of hull shape and length but I'd be hesitant to add a ama to a SUP.  Speed is relative but mobility is a huge part of the fun factor.

[PonoBill]

Amas drag a lot more than you'd think. not only skin friction but reflected wave. There's also the basic rotational torque an ama applies that you need to counter. A lot of sailing outriggers, where the speeds are higher, have asymmetrical hulls to counter the torque. Lots to deal with.

[stoneaxe]

Not that I know much about the subject of outriggers but I think the only reason I'd want one on a SUP is for fishing....and that's just a maybe.

I played around in Sketchup a few years back when I was thinking about making a fishing cruiser.....just a pipe dream so far.

[capobeachboy]

How about a Gull Wing?

[pdxmike]

Adding an ama could be a big moment in SUP design.

[ericjayowsley]

OK. Let's say one were to build a prototype. Would you want the main hull to be mostly round bottomed, like in OC-1 or surfski? Would you want it to transition into a flatter tail? Would there be any merit in a sharper v-bottomed design for on-rails like tracking, perhaps with asymmetry to counteract the ama drag like in a Hobie hull? My other big passion is proa sailing craft. I see wonderful crossover applications here.

[outcast]

I thought my paddle was an ama

it's what we do

Watch the incoming racers in the BOP....

[PonoBill]

Depends on what you wanted it to do. A rounded bottom presents the least skin friction. If you're going to stay out of the surf then a round bottom is fine, if not, then you need something flatter, or you need a way to counter the tendency of round bottom craft to lose rudder authority and round up in surf.

This is a subject that been talked about and even experimented with several times. Most recently for me was yesterday when I stopped at Gorge Performance to shoot the breeze with Bob Reuter. Like any non-technical concept the way to see what would happen is to build one. If anyone were super-serious they'd model this first, but it's pretty easy to stick an ama on a surfski and stand up in it.

I'd do it with small floats and hydrofoils, but that's me. I think GreatDane did a similar experiment that he was enthusiastic about some time ago, but the enthusiasm apparently waned. Probably needs an RC rudder to turn the thing.

I'm also interested in sailing canoes. I recently read Gary Dierking's interesting book about building them. I may have to torture myself with woodwork in Maui this year, or maybe rivet one up out of aluminum.

[headmount]

How about a Gull Wing?

The web site says,  If you're talented enough not to lean too much to either side the tips might never touch the water unless seas are above 1ft. But in this pic the guy is in glass and still touching both sides.  Also added to the fact that in this neck of the woods we're not so  interested until we have 7 foot seas. 

Still it looks interesting.

[PonoBill]

You can also see in that picture something of the effect of the wave interference pattern. All multihull designs have an additional drag component caused by wave interference between the hulls. One more way that physics seems to keep the scales even. Wave-making resistance of any hull is proportional to the square of the beam. So two narrow hulls should give half or less the wave resistance. You also get a better length to draft and length to beam ratio, so the form drag and wave drag picture looks rosy. But when you add in the drag for wave interference the benefits are overcome and the catamaran has to look elsewhere for places where it can be a superior design. You simply don't see any huge catamaran freighters, and that's not because naval architects a blind to the potential. It's mostly structural considerations (restraining two hulls in a big sea ain't easy) but interference drag is part of the picture.

You can lessen interference drag by spacing the hulls far apart, which is one reason why most sailing cats are wide. Of course that also makes them harder to control and more susceptible to broaching, tripping, plunging, and catapaulting the innocent trapeze dude (me) all the way into a few inches of water. You can also pick one hull out of the water, as good OC paddlers and Americas cup boats try to do. Of course if one of those AC72s trips you put people into low earth orbit.

The reason why Mark Raaphorst's Standamaran is fast is that it has a very low prismatic coefficient. The reason it's not faster is the hulls are too close together. If you look down while paddling it there's a cat's cradle of interference patterns that change with speed.

None of this kind of stuff is new, in fact you have to read dusty old tomes written at the turn of the century, when every university with serious technical aspirations had at least one big test tank.

[capobeachboy]

This is dated but pretty cool stuff:

Men’s solo winner is Santo Albright at Missouri River 340 ... yes, the 340 stands for miles.

Santo Albright won the men’s solo division of the Missouri River 340 with a time of 44 hours and 56 minutes on his Huki S1-X Special with Gull Wing. This is Albright’s third time in the race. In 2008 he had a time of 61 hours. Santo won the race in 2009 on his Huki in 51 hours, and now in 2010 knocking off a little more than six hours from his previous win, he has won the Men’s Solo Division again on his Huki S1-X Special with Gull Wing. Santo explained that keeping a constant managable pace was crucial because racers often go at it too hard, wearing themselves down so they have to stop frequently for a break on land. Santo’s strategy was to only take a few short cat naps while drifting down the river race course, using his Huki Gull Wing stabilization system to keep him upright and steady.

[headmount]

Yeah I could see how it would be great for cat naps but if I'm sleeping I'd prefer my bed. 

When we go around here, we're usually into going as hard as possible and collapse at the finish.  During that time period, performance is pushed to the max because conditions offer it and competition is always there.  It's intense.

But for what that guy's record, it sounded perfect.  I've heard the Missouri is rather rough in places.  At roughly 7.5/MPH he was cooking.

[paddlebuilder]

Not saying this is a good idea by any means, but a friend has insisted that he wants something like what's pictured but with flat rocker and shorter ama's.....we have the main hull almost ready for stripping at this point.  Like I said, I would never create such a craft for myself but my bro is paying and really wants this.  The hull is 12" wide with a wider standing deck.  So really just tossing this out as another example of where creative energy takes creative people.  For me I'll stick with my various "woodie" sups.

[capobeachboy]

Yea I don't catnap too well standing up.  Works much better sitting down.