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Geodesic Airolite Boat with a twist
I'm looking at building a Geodesic Airolite Boat, (see www.gaboats.com
by Platt Monfort) but I'm considering an interesting idea and I'm wondering what you all might think. Instead of using wood strips to form the geodesic structure I am thinking about using foam strips wrapped in Kevlar tape and epoxy. I have been reading about the construction of these boats and found that some people have trouble with bending the ribs to shape without breaking, (and this is with better quality wood that I am able to source). I'm thinking I can bend foam cores easily to shape and then once assembled in a frame start wrapping it all in Kevlar tape, forming a makeshift Kevlar tube frame. I'm still considering using wood for the stringers and gunwales as I can form those with little or no problem. Having the stringers and gunwales constructed out of wood would also make forming the foam ribs much easier as it would give me something solid to work the foam inside. -Does anyone foresee a problem with pursuing this type of construction? -How will Kevlar wrapped foam compare to the equivalent cross-sectional wood piece in strength? Thanks Jordan Richardson |
Geodesic Airolite Boat with a twist
"Snowman" wrote in message om... I'm looking at building a Geodesic Airolite Boat, (see www.gaboats.com by Platt Monfort) but I'm considering an interesting idea and I'm wondering what you all might think. Instead of using wood strips to form the geodesic structure I am thinking about using foam strips wrapped in Kevlar tape and epoxy. I have been reading about the construction of these boats and found that some people have trouble with bending the ribs to shape without breaking, (and this is with better quality wood that I am able to source). I'm thinking I can bend foam cores easily to shape and then once assembled in a frame start wrapping it all in Kevlar tape, forming a makeshift Kevlar tube frame. -Does anyone foresee a problem with pursuing this type of construction? -How will Kevlar wrapped foam compare to the equivalent cross-sectional wood piece in strength? Potential problems: The foam is not as stiff as the wood, so you may need to shorten the spacing between molds in order for them to lie fair. I think laying up glass tube is not as easy as it sounds, but a dedicated person can make it happen. I see it as being really hard to keep the foam tubes fair during the layup process. I think construction will go much faster with wood, as long as you can find decent stock. Find a wood that bends easily, without a lot of grain runout.. As far as strength goes, it can be as strong but I don't think it will be as stiff. Wood is an incredibly stiff material for its weight, so does a good job keeping the structure rigid. In essence, the GA boats rely on the skin to keep the water out, and the shape is held by the wood. If you don't have as stiff an internal structure, the boat might be a little more bendy than you like. This may or may not be a good thing - some eskimo kayaks were pretty flexible. Whether this bothers you or not may be a matter of taste. Matt |
Geodesic Airolite Boat with a twist
I'd recommend buying some Kevlar and trying your idea out, with the wood
versions next to it. Kevlar is tough enough to lay on a smooth flat surface. You may find that it's more hassle than it's worth unless you vacuum bag it. Try it first. Prove me wrong. Test the results mechanically ...clamp the samples to a table (your composite and the wood) and hang weights off the end to find out how much each deflects versus the other and where the breaking point occurs and how it breaks. Most of all, have fun. Brian -- http://www.advantagecomposites.com/tongass -- My 22' Tolman Skiff project http://www.advantagecomposites.com/catalog -- Discounted System Three Resins products .. "Snowman" wrote in message om... I'm looking at building a Geodesic Airolite Boat, (see www.gaboats.com by Platt Monfort) but I'm considering an interesting idea and I'm wondering what you all might think. Instead of using wood strips to form the geodesic structure I am thinking about using foam strips wrapped in Kevlar tape and epoxy. I have been reading about the construction of these boats and found that some people have trouble with bending the ribs to shape without breaking, (and this is with better quality wood that I am able to source). I'm thinking I can bend foam cores easily to shape and then once assembled in a frame start wrapping it all in Kevlar tape, forming a makeshift Kevlar tube frame. I'm still considering using wood for the stringers and gunwales as I can form those with little or no problem. Having the stringers and gunwales constructed out of wood would also make forming the foam ribs much easier as it would give me something solid to work the foam inside. -Does anyone foresee a problem with pursuing this type of construction? -How will Kevlar wrapped foam compare to the equivalent cross-sectional wood piece in strength? Thanks Jordan Richardson |
Geodesic Airolite Boat with a twist
If you have not built one of these boats before I'd recommend watching the
video. I've not built one but have watched the video fo which the Ottawa library has a copy. TF Jones, who has built one, said he had to watch the video to see how it was done. It's normal to break a few ribs when stema bending them into a hull. The video shows how to do it. For foam ribs it might be better to form them over the outside of the hull and then press them into the interior and trim the ends. To do this the foam would have to be pretty thin. I think you'll end up adding weight to the boat. Other variations have been tried on these boats, eg using plastic stringers instead of wood and using polyester cord instead of kevlar (both are used in car tires, mostly polyester). I imagined fitting thin foam strips between the stringers to provide some backing to prefvent punctures, give the hull stiffness, and eliminate the condensation on the inside of the hull. -- ------------------------------------------------------------------------------ William R Watt National Capital FreeNet Ottawa's free community network homepage: www.ncf.ca/~ag384/top.htm warning: non-freenet email must have "notspam" in subject or it's returned |
Geodesic Airolite Boat with a twist
Kevlar floats on top of resin. So it has to be vacuum bagged. One issue
I could see is if you were trying wrap the strip completely in kevlar. Not sure how well it would bend around a 90 degree edge. And that's 90 degrees F or C. (a little early morning humor... ;p ) -- Matt Langenfeld JEM Watercraft http://jem.e-boat.net/ Brian D wrote: I'd recommend buying some Kevlar and trying your idea out, with the wood versions next to it. Kevlar is tough enough to lay on a smooth flat surface. You may find that it's more hassle than it's worth unless you vacuum bag it. Try it first. Prove me wrong. Test the results mechanically ...clamp the samples to a table (your composite and the wood) and hang weights off the end to find out how much each deflects versus the other and where the breaking point occurs and how it breaks. Most of all, have fun. Brian |
Geodesic Airolite Boat with a twist
On 30 Apr 2004 04:22:27 -0700, (Snowman)
vaguely proposed a theory .......and in reply I say!: remove ns from my header address to reply via email Maybe I was OOL with my comments. Are these "ribs" _just_ wood, or are they formers that are then glassed in? If they are just ribs then wood in the way to go...learn how to bend wood. If they are later glassed in, then the mech, properties of the ribs become far less important. Compressibility (pinching) becomes more important than stiffness. The best solution would be kerfed wood; easily bent, hard to compress/pinch. I _still_ don't see how these fit the "geodesic" mould. Remember that with lightweight craft, skin penetration can become a problem. from my kayaking experience, the boat will hole well before it folds. Kayaks are very strong, because their cigar shape makes then that way. Building a boat with a super-thin skin, stiffened by stringers, will aid this. I suppose kevlar etc will go a long way down that path. I would prefer to go on a high protein diet and add a couple of kilo to the boat! I'm looking at building a Geodesic Airolite Boat, (see www.gaboats.com by Platt Monfort) but I'm considering an interesting idea and I'm wondering what you all might think. Instead of using wood strips to form the geodesic structure I am thinking about using foam strips wrapped in Kevlar tape and epoxy. I have been reading about the construction of these boats and found that some people have trouble with bending the ribs to shape without breaking, (and this is with better quality wood that I am able to source). I'm thinking I can bend foam cores easily to shape and then once assembled in a frame start wrapping it all in Kevlar tape, forming a makeshift Kevlar tube frame. I'm still considering using wood for the stringers and gunwales as I can form those with little or no problem. Having the stringers and gunwales constructed out of wood would also make forming the foam ribs much easier as it would give me something solid to work the foam inside. -Does anyone foresee a problem with pursuing this type of construction? -How will Kevlar wrapped foam compare to the equivalent cross-sectional wood piece in strength? Thanks Jordan Richardson ************************************************** ** The Met Bureau is LOVE! |
Geodesic Airolite Boat with a twist
Old Nick says:
Are these "ribs" _just_ wood, or are they formers that are then glassed in? Nick, I would HEARTILY recommend you check out the geodesic boat site at www.gaboats.com before you get past your ankle there ;-) It certainly sounds as though you haven't "got" the concept. Not 'ffense, or anything, just an observation. Steve |
Geodesic Airolite Boat with a twist
My only concern would be keeping constant the frame material.
Especially if you are laying this stuff up by hand. If you want to use Kevlar for a Kayak, use it for the skin, laid over fiberglass etc, not for the frame, only my opinion. Scotty from Sm... oh, I just can't do it, not for a nothing answer... |
Geodesic Airolite Boat with a twist
On 01 May 2004 21:26:39 GMT, ospam (Stephen Baker)
vaguely proposed a theory .......and in reply I say!: remove ns from my header address to reply via email Old Nick says: Are these "ribs" _just_ wood, or are they formers that are then glassed in? Nick, I would HEARTILY recommend you check out the geodesic boat site at www.gaboats.com before you get past your ankle there ;-) Sorry. Don't get ya. It certainly sounds as though you haven't "got" the concept. Not 'ffense, or anything, just an observation. Yeah I had looked but did not pick up on the diagonals. I also did not pick up that it's not glassed, but shrink-wrapped...hhhmmmm... ok. ************************************************** ** The Met Bureau is LOVE! |
Geodesic Airolite Boat with a twist
Old Nick says:
before you get past your ankle there ;-) Sorry. Don't get ya. Reference to how far your foot may have travelled into your mouth.... Nothing personal. ;-) Steve |
Geodesic Airolite Boat with a twist
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Geodesic Airolite Boat with a twist
Old Nick says:
hmmmm...I would be careful on the Web. "nothing personal" is easy for _you_ to decide when you say it, smiley or not. G I know.... Believe me, I know. ;-))) And thanks for correcting me. De nada. I once got to the "up to my knee" stage before realising what was going on. Not a pretty sight, or feeling. Steve "size 15" |
Geodesic Airolite Boat with a twist
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Geodesic Airolite Boat with a twist
Old Nick says:
Ah! Yes. My best one was here, where they started talking about using windmill on a boat to sail straight upwind. After I was allowed to make a complete idiot of myself for a while, I was informed to treat it as being like a boat tacking constantly. I slunk away. But I DID come back and admit my error! Heehee - I remember that one. A classic. ;-) Steve |
Geodesic Airolite Boat with a twist
On 30 Apr 2004 04:22:27 -0700, (Snowman)
vaguely proposed a theory .......and in reply I say!: remove ns from my header address to reply via email OK. I am now on track as to how these things are built. Sorry about my misguided attempts. My feelings: As has been saidKevlar would be a difficult material to use to make ribs as you suggest. Try epoxy/glass. I cannot see any troubles. Although the foam is softer than wood, the glass (kevlar) skin is what makes a foam/glass frame stiff, and stiff it would be. Make the "walls" heavier than the "roof (inner) and "floor" (outer) skins. make the floor heavoer than the roof. Having said that, if the bending is the problem, I still reckon that you could use kerfed wood, to make it easier to bend, over an armature. My trial methos would be kerf and bend with the kerfs inside the cirve, so that the outer side, at first was fair and not blocky. You would have to make enough kerfs, each kerf wide enough, to allow the bend. This would then be covered with the glass skin, as much as possible, and then turned and glassed on the remaining side once dry. Careful work and a fair bit of it. The advantage of using wood as a core over foam is that the skins can be thinner without fear of have easily-punctured walls. In the end you would have to try a few of these and test the strength/weight ratio of these vs straight (bent!G) wood. Strength in this case to my mind would include some sort of stanadard crushing test. I still wonder if all this weight saving is worth the trouble....I can see it being useful in extreme situations of portability, and careful usage. I'm looking at building a Geodesic Airolite Boat, (see www.gaboats.com by Platt Monfort) but I'm considering an interesting idea and I'm wondering what you all might think. Instead of using wood strips to form the geodesic structure I am thinking about using foam strips wrapped in Kevlar tape and epoxy. I have been reading about the construction of these boats and found that some people have trouble with bending the ribs to shape without breaking, (and this is with better quality wood that I am able to source). I'm thinking I can bend foam cores easily to shape and then once assembled in a frame start wrapping it all in Kevlar tape, forming a makeshift Kevlar tube frame. I'm still considering using wood for the stringers and gunwales as I can form those with little or no problem. Having the stringers and gunwales constructed out of wood would also make forming the foam ribs much easier as it would give me something solid to work the foam inside. -Does anyone foresee a problem with pursuing this type of construction? -How will Kevlar wrapped foam compare to the equivalent cross-sectional wood piece in strength? Thanks Jordan Richardson ************************************************** ** The Met Bureau is LOVE! |
Geodesic Airolite Boat with a twist
"Old Nick" wrote in message ... My feelings: As has been saidKevlar would be a difficult material to use to make ribs as you suggest. Try epoxy/glass. I cannot see any troubles. Although the foam is softer than wood, the glass (kevlar) skin is what makes a foam/glass frame stiff, and stiff it would be. Make the "walls" heavier than the "roof (inner) and "floor" (outer) skins. make the floor heavoer than the roof. I think this is where people often mistake stiffness versus strength. Plain vanilla fiberglass is about the same stiffness as wood. In other words, make a 1 inch by one inch by 12 inch stick of wood, clamp it onto your workbench, and put a five pound weight on the end. It bends about what, a half inch? Make a 1 inch by one inch by 12 inch stick of fiberglass, put the same five pound weight on the end, and it will bend about a half inch as well. Now the fiberglass will support more weight before it breaks, but it's also about three times heavier. Give me three times more wood to use, and if I can make the beam a one by three, then I can approach the load strength of the glass. Wood is good stuff for resisting bending. I call it a naturally occuring unidirectional carbon fiber reinforcement ;=) I could go further into the engineering analysis and try to come up with some numbers for equivalent stiffness of glass or kevlar cored stringers. They'll either need to be larger in section or solid glass. But in the end it sure seems like it's going to be a lot of extra labor to build it that way, when the time could be used to find some decent regional straight grained boatbuilding lumber. Just MHO. Assuming that decent boatbuilding wood really is too difficult to find, then I do like your idear of cutting kerfs on the wood stringers, framing and skinning the boat, then filling the kerfs with epoxy/wood dust and covering the kerfed face with glass. Matt |
Geodesic Airolite Boat with a twist
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Geodesic Airolite Boat with a twist
Old Nick says:
*******! Definitely, by nature. Not by birth - some of us have to WORK to achieve that status. ;-) |
Geodesic Airolite Boat with a twist
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Geodesic Airolite Boat with a twist
Snowman,
Having built 4 or 5 of Platt Monforts ultra light canoes, I have a few observations: The concept of Kevlar wrapped foam ribs would probably be do-able, but I guess I'm wondering what you hope to gain. Are you trying to make it stronger? lighter? I'm wondering, how much weight can you expect to save on a 14 pound boat? If the only reason is to avoid the heartbreak of broken ribs during construction, it hardly seems worth the bother. As for bending the ribs, I'll share my secret recipie. First, you must realize that every wood bending method will likely result in some breakage - the question is - can the number of ribs broken during the bending process be kept to an acceptable limit? I always make 3 or 4 extra ribs for a 12 ft canoe which requires 16 ribs, total. Sometimes I'll need one or two of my extras, but I've never needed more than that. Whatever wood you use, it will have to be selected for straight grain - very little or no run out. I have had very good success with SASSAFRASS (that's the secret ingredient). I know this is not a standard item at Home Depot, but there are two lumber dealers in my hometown of Springfield, Missouri where I can buy decent sassafrass boards. Find out where your local cabinet makers buy their lumber - sometimes it's sold as a substitute for ash (you can make a positive ID by the smell). If you live in the southeastern US, inquire at small local lumber mills. Sassafrass is lighter than most hard woods, though a tad heavier than the soft woods suggested by Montfort. It's an excellent wood for boats - weather resistent, glues and finishes well, easily worked with hand tools, and bends beautifully. At first I steamed my ribs in a PVC pipe rigged up to a metal gas can (NEW - NOT USED!) on a Colman stove, but I discovered this is unnecessary. Now I just run a few inches of hot water in the bath tub and submerge them for a few hours before bending. If it's a really tight bend, I might put a presoaked rib in my PVC pipe, now capped on one end, and pour a teakettle of boiling water over it for a few minutes just before bending. Good luck, GW (Snowman) wrote in message . com... I'm looking at building a Geodesic Airolite Boat, (see www.gaboats.com by Platt Monfort) but I'm considering an interesting idea and I'm wondering what you all might think. Instead of using wood strips to form the geodesic structure I am thinking about using foam strips wrapped in Kevlar tape and epoxy. I have been reading about the construction of these boats and found that some people have trouble with bending the ribs to shape without breaking, (and this is with better quality wood that I am able to source). I'm thinking I can bend foam cores easily to shape and then once assembled in a frame start wrapping it all in Kevlar tape, forming a makeshift Kevlar tube frame. I'm still considering using wood for the stringers and gunwales as I can form those with little or no problem. Having the stringers and gunwales constructed out of wood would also make forming the foam ribs much easier as it would give me something solid to work the foam inside. -Does anyone foresee a problem with pursuing this type of construction? -How will Kevlar wrapped foam compare to the equivalent cross-sectional wood piece in strength? Thanks Jordan Richardson |
Geodesic Airolite Boat with a twist
G D Wright ) writes:
... I have had very good success with SASSAFRASS TF Jones also writes about preferring sassaras for steam bending -- ------------------------------------------------------------------------------ William R Watt National Capital FreeNet Ottawa's free community network homepage: www.ncf.ca/~ag384/top.htm warning: non-freenet email must have "notspam" in subject or it's returned |
Geodesic Airolite Boat with a twist
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