Minimal proa
Simplified aka to ama coonection and removed as many straight lines as possible. The vaka does have a shear line but it seams to have got lost, I will look at this next.
I am also trying to improve the rendering quality, the cad has a fancy render mode but I can’t find the lighting controls.
TINK
A few more pictures, vaka and the ama don’t look in harmony with each other
TINK
Shear line updated, aka ama connection brought in line with vaka.
I am now finalising construction details and checking that it economically fits on sheets of ply, would be a shame to need an extra sheet foe the odd mm.
Hey Tink, I own and sail an IC myself, in fact it is an ex UK boat (GBR212). I agree that a proa could potentially offer the same sort of experience while being a little less demanding. My IC has similar performance to many off the beach catamarans, but is lighter and has less sail area. I like the idea that a small proa could be similarly light and easily handled on shore and into the water, without sacrificing performance.
Greetings, mr TINK
I like the simplifications you’ve made the last few posts. Some critique you are free to ignore 😊 :
Have you looked at the strength of the ama attachments? Would the ply bend under sideways loading? I’m also curious how the tubes connect to the supports. Lashing?
Would the main hull take a bit more sheer? Maybe also give the sheer the same sort of line as the hull has in plan view, if that makes sense. (Not sure about this, I’m sure you’ve played around with it a lot already.)
I’d love to build something like this if I had the time.
Greetings,
Thomas
Greetings Thomas,
All feed back great fully received.
I have taken my inspiration for the Ama from the P5 proa, this seams to have been used on quite a number of proas in the Baltic area according to my research. (http://www.multihull.de/proa/p5/p5gb.htm). There is an wae or transfers beam under each ama hope fully tie-ing the two up rights together. All the supports are 9mm ply.
For the lashings each aka would have a looped strop (purple) and I would then use an endless ratchet to tension these, (blue and black) just an idea at the moment, may use a more conventional lashing and a cleat.
If ever one thing gets more attention than anything else in boat design it must be the shear line. I have laid the panels out on ply and it will need 4 sheets with plenty of room, so I can easily adjust the shear line. I think i will draw it out full size. Despite being constructed simply and of flat panels I want to make it as good looking as possible.
I got the nod to build it yesterday off my wife, she said ’ with all this designing you going to want to build another boat aren’t you?’ I simply responded ‘yes’ to which I received a scowl, which is as good as a yes to me. I am getting a quote for CNCed panels with slot and tab to make self jigging. Based on my TP03 build I figure it would be easy to built in less than 100 hours. I am an early riser so at weekends usually in the garage by six. I have a portable door bell and when the family wake they ring it to call me in, I usually get a few hours the odd night during the week as well. Keeps the family sweat.
Thinking calling him WeeWaka, sounds better than minimal proa.
TINK
One of the major reasons to go to a solid foam surfboard style construction on the Bionic Broomstick was the difficulty in filleting the inside joins on a 8” (max) hull 20” deep. Any scheme to work in the ends took it out of the easy simple build category.
Minimal proa has a lot of appeal, BB was conceived primarily as a testbed for features on the proa I really want to build but it is looking better on it’s own merits.
But… there’s always the comparison to a little double blade solo canoe which is the gold standard in bang for the buck. I’m off for a week on the Buffalo National River in Arkansas to explore same.
cheers,
Skip
Dear Skip
Hope you have had a good trip.
I have almost completed the concept phase of my minimal proa (WeeWaka) and I saw a picture of Chris Luomanen’s Snelson’s canoe. It got me thinking no mater what I do a WeeWaka made of flat sheets of ply is never going to look as good as carved foam and glass hull. So I have done a few very rough calculations based on the following spec
LOA 3.7m x Beam 0.24m x Hull depth o.36m, 12.1’ x 9.5” x 14”
Total volume 250 lt 8 cu ft
Sheathing single layer 200g (6oz) glass with epoxy
Foam 32kg/ m cu 2lb cu ft
Shear web 3mm 1/8th inch
Plus local reinforcement
Very ball park weight 15kg (33lbs), how does that sound spec wise and weight estimate against Bionic Broomstick? Just feel I must explore all avenues before I make a final decision.
TINK
Hi Tink,
Had a great trip on the Buffalo, miles and miles (about 80) of pristine rock bluffs, clear water and early early spring foliage.
Back to,proas, I’ll weigh the Broomstick this evening and get back to you, it’s still assembled under the house while I slowly diddle out the ergonomics of sheet locations, tiller details and the like. I’ll weigh the whole thing this evening (less rig) and get back to you. Hope your shoulder is still improving.
Skip
I have taken my inspiration for the Ama from the P5 proa, this seams to have been used on quite a number of proas in the Baltic area according to my research. (http://www.multihull.de/proa/p5/p5gb.htm). There is an wae or transfers beam under each ama hope fully tie-ing the two up rights together. All the supports are 9mm ply.
Hi TINK,
I designed the P5 nearly 10 years ago. The main aspect of this solution was the use of a tension belt for fast assembling/disassembling, and the best force fransmission from the beam holder into the shell plate. Further this kind of beam holder can used to connect single plywood plates for hull side by overlapping with it. This principle I used for building the P8 too. It works very well.
Hi Tink,
Had a great trip on the Buffalo, miles and miles (about 80) of pristine rock bluffs, clear water and early early spring foliage.
Back to,proas, I’ll weigh the Broomstick this evening and get back to you, it’s still assembled under the house while I slowly diddle out the ergonomics of sheet locations, tiller details and the like. I’ll weigh the whole thing this evening (less rig) and get back to you. Hope your shoulder is still improving.
Skip
Sounds like a great trip.
Thanks for offer to weigh Broomstick will be very interested in what he comes out at.
At the hospital today, have the sling off, lots of physio required so a good few weeks before I get TP03 on the water
TINK
I have taken my inspiration for the Ama from the P5 proa, this seams to have been used on quite a number of proas in the Baltic area according to my research. (http://www.multihull.de/proa/p5/p5gb.htm). There is an wae or transfers beam under each ama hope fully tie-ing the two up rights together. All the supports are 9mm ply.
Hi TINK,
I designed the P5 nearly 10 years ago. The main aspect of this solution was the use of a tension belt for fast assembling/disassembling, and the best force fransmission from the beam holder into the shell plate. Further this kind of beam holder can used to connect single plywood plates for hull side by overlapping with it. This principle I used for building the P8 too. It works very well.
The mounts I can see in the picture look like what I am thinking of, do you know how thick the ply was and would you do it the same way again?
Thanks
Tink
The Bionic Broomstick currently weighs 82#
Supported at the center of the float and just behind the rudder pods at each end of the hull on one gallon paint cans a scale was inserted at each point with the following results. Float 20#; each end 31#.
Boat is fairly complete, no finish except for graphite/epoxy on hull bottom, need mast, sail, boom and tillers.
Basic build is 2#/cu ft foam, 9 oz fiberglass, 1x4 box beam w/ 5.2 mm ply webs, padded plastic fisherman’s chair and cored fiberglass sockets for the beam/hull/float connections.
Hope that helps
Skip
The Bionic Broomstick currently weighs 82#
Supported at the center of the float and just behind the rudder pods at each end of the hull on one gallon paint cans a scale was inserted at each point with the following results. Float 20#; each end 31#.
Boat is fairly complete, no finish except for graphite/epoxy on hull bottom, need mast, sail, boom and tillers.
Basic build is 2#/cu ft foam, 9 oz fiberglass, 1x4 box beam w/ 5.2 mm ply webs, padded plastic fisherman’s chair and cored fiberglass sockets for the beam/hull/float connections.
Hope that helps
Skip
Thanks Skip that is very interesting and useful.
Lots to think about, I think both ply and foam would come out about the same weight, the foam could look nicer but ply is in my comfort zone. I am contemplating a hybrid, ply underwater and structure, then add decks nicely carved in foam.
Unfortunately my shoulder getting better has it’s down sides, I have returned to work and have a mountain of catching up to do. Much less time working on proa designs but on the plus side my shoulder is on the mend and summer and sailing are on their way.
Thanks again
TINK
Partial sketch of hybrid and full foam below
TINK
The mounts I can see in the picture look like what I am thinking of, do you know how thick the ply was and would you do it the same way again?
Thanks
Tink
Yes I would. The picture shows the 5 m ama of the P8 made of 6 mm plywood. I doubled the mount over the shelfs edge, and strenghten it outside with 6mm too. At last the mount was 18 mm thick. There was never a problem with stability. On 8 m vaka the mounts gets a fourth layer outside up to 24 mm.