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#1
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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 |
#3
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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 |
#4
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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 |
#5
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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 |
#6
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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 |
#7
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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! |
#8
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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 |
#9
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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... |
#10
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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! |
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