Outrigger canoe Ama design considerations

Hi, I recently acquired a 20' x 19" surfski kayak with the intentions of converting it into an OC-1 style one-man outrigger canoe. I have some design and fabrication experience, but not on a project like this. The first picture is a photo of the surfski kayak and the other is the surfski with a comparable outrigger canoe overlaid to give you an idea what I hope to do.

I see two main issues: design of the ama (outrigger float) beams and fittings and second, the fabrication. The existing kayak is of unknown composite construction. At present I'm leaning towards "surfboard" construction (foam core and epoxy / fiberglass skin) for the ama/float and an aluminum box tube from the kayak to the ama. I haven't decided on how to connect the aluminum beams to the kayak or ama yet.

Anyone here take on a project similar to this and have some advice or suggestions?

 

I recommend you get Gary Dierking's book, How to Build an Outrigger Canoe.

worth every penny

@garydierking

 

A lot will depend on the desired venue. The original OC1's were open water craft with "banana" shaped amas which were well suited to large open swell water. My experience is with river racing craft and that elegant underhull rudder on your boat would be a serious concern on the Missouri River or the Texas Water Safari. That being said glass/epoxy over foam is an ideal medium for the float, just don't use the beaded crap. Aluminum tubing, 6061 t6 or similar maybe 1" minimum diameter, 0.058 wall or better would work ok for beams. No recommendations for connectors.

From long ago and now somewhat far away Duckworks - A Journey Off to One Side https://www.duckworksmagazine.com/12/designs/pproa/index.html the link has gotten a little iffy but you might find it interesting. Fallguy is right, get Gary's book.

 

Calling Skip Johnson a junior member is just plain wrong!

 

Just because I'm older than dirt

 

Not to mention this ain't your first rodeo !!

 

Thanks Skip. I hope to use this for open ocean downwind paddles where shallow water is only an issue when launching and landing. The article you linked to and your feedback is exactly the kind of info I hoped to get. Thanks again! Paul

 

Hi Paul. How are you coming on your ama design and build? I've a few questions and thoughts if you are still undecided.

 

I'm still collecting ideas and looking for possible suppliers for the materials I will need. I am undecided on whether to add one ama (such as you'd see on an OC-1 racing canoe) or two. I have an older Epic V10 Sport surfski that is extremely light (25 lbs) for a 20 foot boat so I am also considering different ways of attaching the beams to the hull.

 

So basically something like one of the attached photos:

 

So many variables. These latest pics make me think you are mainly looking for a little added stability when out in big water and not so much the OC-1 experience. Is that right?

 

I haven't decided yet although I am leaning towards making it similar to an OC-1 in the event I ever decide to sell it. But I have no plans on racing so I'm free to do whatever I want. My wife suggested that I make it an OC-1 with the ability to add a second ama later if I decide I want one, and that sort of makes sense. My biggest limitation is my access to suitable building materials. If it isn't at my local big box hardware store or easily ordered on-line, then I can't get it.

 

I wonder why modern OC-1 designs don't include a more modern shaped ama? Such as this very modern sailing trimaran.

 

Hi Paul. To answer your last post first. They are two way different watercraft, with different power sources, and different speed potentials. OC-1 racers can tell the slightest nuance of efficiency between different amas. The sophistication of OC-1 development is every bit that of multihull design. I have a carbon/kevlar surf ski same length and width as your V10 but much more tippy. It vees down and ends with a small radius at the bottom. I needed training wheels for it and have tried different setups. I have some ideas for you when I have more time.

 

I look forward to hearing your ideas.