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Anyone familiar with the different types of carbon fiber tubing?

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  • gellfex
    replied
    Originally posted by BCRider View Post
    When you get it done perhaps post an update. It sounds like an interesting rig and it would be interesting to read your feelings about it.

    I've been looking at doing a lightweight nesting boat for rowing and sailing using one of the old windsurf rigs for the sailing part. The hull design I'm currently keen on is the Duck Punt design. The folks with them don't use a lee board at all. Just tip the leeward rail into the water for side resistance. If/when I do it I would use the okume plywood I bought for something like this about 25 years ago and which is well cured by now So stitch and tape with light epoxy glass overall over a hull made from the 5mm thick plywood for the most part.
    I've seen with this rig how important the leeboards are, without anything you're just not going to be able to point, even on a reach you'll be making huge leeway. I've seen dinghy rigs with windsurfer sails, but it's way too much sail area for a kayak. This rig has only 1.4 sq m and I still went over! To be fair, it does have a reefing feature that I might have been prudent to use in those conditions. But the airs that will get this thing moving but not scary are a narrow window from 10 to 20 mph.

    Below is the 3nd attempt at a sliding leeboard accessory to aid pointing. Seemed to work pretty well till I flipped. I think I may reduce the area like 20%. Each side is a layer of matt and a layer of cloth, didn't add much to the cross section. I'm planning on screeding some Bondo over the cloth to make the surface smooth. The plate is 1/8" Garolite. I thought the blade was carbon but it's glass impregnated nylon.

    Click image for larger version

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  • BCRider
    replied
    When you get it done perhaps post an update. It sounds like an interesting rig and it would be interesting to read your feelings about it.

    I've been looking at doing a lightweight nesting boat for rowing and sailing using one of the old windsurf rigs for the sailing part. The hull design I'm currently keen on is the Duck Punt design. The folks with them don't use a lee board at all. Just tip the leeward rail into the water for side resistance. If/when I do it I would use the okume plywood I bought for something like this about 25 years ago and which is well cured by now So stitch and tape with light epoxy glass overall over a hull made from the 5mm thick plywood for the most part.

    Leave a comment:


  • gellfex
    replied
    Originally posted by BCRider View Post

    My bad then. I thought it would have been the lower main mast. Yeah, I can see why you'd want a lighter up that high.

    Does the upper piece need any cross holes drilled into the mid area of the length? And if there is a hole is that where the original snapped?

    If a cross hole is needed then I'm thinking that would put a carbon tube out of the running. Too many critical fibers being cut. The whole reason carbon can work is because the fibers are continuous from end to end. Carbon parts on racing bicycles have been known to fail shortly after a small nick that cut into a short run of fibers was caused by a crash. Carbon fiber apparently paid a lot of extra attention during class when "stress risers" were being discussed and embraced the concept deeply ....

    If a middle fitting is needed then perhaps something that permits a change to an outer wrap around style of securing the head mast instead of a thru hole could be devised?

    As for going out in the cold for fishing? You're a braver man than I Gunga Din ! ! ! At that time of year and knowing how nasty it can be in the North East (8 years in southeast Ontario here) I salute you. But my own preference for fishing at that time of year in the local market thankyouverymuch....



    There is a small cross hole holding it to the sliding bracket, but it's pretty small perhaps a number four, and it exactly isn't where the break occurred.

    This time of year I'm not an idiot, I wait for a nice day! At least above 50, preferably sunny. Back when I paddled whitewater and was young and full of piss and vinegar, I'd be out there in the thirties. One time we had to get out and walk because the river was iced over.

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  • BCRider
    replied
    Originally posted by gellfex View Post

    The broken spar is the top mast not the main mast.

    And my kayaking season is not over yet! My last trip last year was very close to December, and I think I've paddled in December too. The problem is the blackfish season in New Jersey doesn't open until November 15th!
    My bad then. I thought it would have been the lower main mast. Yeah, I can see why you'd want a lighter up that high.

    Does the upper piece need any cross holes drilled into the mid area of the length? And if there is a hole is that where the original snapped?

    If a cross hole is needed then I'm thinking that would put a carbon tube out of the running. Too many critical fibers being cut. The whole reason carbon can work is because the fibers are continuous from end to end. Carbon parts on racing bicycles have been known to fail shortly after a small nick that cut into a short run of fibers was caused by a crash. Carbon fiber apparently paid a lot of extra attention during class when "stress risers" were being discussed and embraced the concept deeply ....

    If a middle fitting is needed then perhaps something that permits a change to an outer wrap around style of securing the head mast instead of a thru hole could be devised?

    As for going out in the cold for fishing? You're a braver man than I Gunga Din ! ! ! At that time of year and knowing how nasty it can be in the North East (8 years in southeast Ontario here) I salute you. But my own preference for fishing at that time of year in the local market thankyouverymuch....




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  • gellfex
    replied
    Originally posted by Noitoen View Post
    Didn't read all the posts. Could use the lower section of a fishing rod made from fiberglass or carbon fiber.
    We're well beyond that, these guys are dubious wether I'll be safe with a 19 mm outside 16 mm inside carbon tube, far heavier than any fishing rod.

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  • Noitoen
    replied
    Didn't read all the posts. Could use the lower section of a fishing rod made from fiberglass or carbon fiber.

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  • gellfex
    replied
    Originally posted by BCRider View Post

    And how heavy is the whole rig? And how heavy is the boat with rig? It's a lug or modified lug rig with the potential steel portion being the short main mast mounted off the deck rail. So it's in c
    lose to the center of mass. In a capsize would a pound to pound and a half in that close to the hull make a difference that could be noticed?
    The broken spar is the top mast not the main mast. Yeah my "100% failure" data set is one event, but breaking a mast on a capsize even 50% or 25% of the time is not acceptable.

    And my kayaking season is not over yet! My last trip last year was very close to December, and I think I've paddled in December too. The problem is the blackfish season in New Jersey doesn't open until November 15th!


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  • mattthemuppet
    replied
    Originally posted by gellfex View Post

    That all sounds perfectly reasonable. But still, compared to the aluminum which failed at its first test, do you really think I can go wrong?
    I couldn't really say one way or another, it's all armchair engineering from this end The only way to know is to fit a CF pole and capsize your kayak, see if it holds and if the rest of the mast and mechanism also holds.

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  • BCRider
    replied
    Originally posted by gellfex View Post

    Well, considering the 6061 spar is 2/3 of a lb, a few lbs would be a lot! Actually, relative density is 2.8 to 8 g/cm3, so a SS spar would be 1.88 lb. No, not the end of the world, but not optimum. The tensile strength of the steel is not quite 2x that of AL, so losing wall thickness seems counterproductive, unless the way SS reacts to this sort of stress is different from AL. Would the extra lb up top be dramatic to the performance? I guess it's hard to see how directly, but the whole rig is so light it's still worrisome.
    And how heavy is the whole rig? And how heavy is the boat with rig? It's a lug or modified lug rig with the potential steel portion being the short main mast mounted off the deck rail. So it's in close to the center of mass. In a capsize would a pound to pound and a half in that close to the hull make a difference that could be noticed?

    Mind you.... I know all to well how "we" sailing types think when it comes to these things. I've been there with my boards and rigs chasing down just the right parts in the hope that it would improve performance or make me suddenly a gifted wind surfer that gybes on a dime. And noticing that you're in New Jersey I'm guessing that it'll be a while before you will be looking at sailing again. Lots of time to find a good replacement even if the guy off Ebay can't help in the end. So sure, if this present carbon tube source doesn't work out keep going.

    There's another option too. It may have been a freak situation that broke the original mast. A direct aluminium replacement might not ever have an issue again. Perhaps just a direct replacement?

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  • gellfex
    replied
    Originally posted by mattthemuppet View Post
    from what I know about carbon fiber the numbers above are meaningless. CFs properties is exactly what the designer wants them to be, based on layup, short vs. long weave, direction, percent resin, chopped fibers vs weaved mat, how the piece is cooked and on and on. All of which affect elasticity (and in which direction and under what conditions), density, strength, stiffness and so on. I'm not saying that a piece of off the shelf CF pipe won't work for you, but unless you have the specs modeled for that particular layup and mix, then there's no real way of knowing what you're getting. It's like saying you're going to build your house out of stone - ok, what stone? How? How thick? etc etc.
    That all sounds perfectly reasonable. But still, compared to the aluminum which failed at its first test, do you really think I can go wrong?

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  • mattthemuppet
    replied
    from what I know about carbon fiber the numbers above are meaningless. CFs properties is exactly what the designer wants them to be, based on layup, short vs. long weave, direction, percent resin, chopped fibers vs weaved mat, how the piece is cooked and on and on. All of which affect elasticity (and in which direction and under what conditions), density, strength, stiffness and so on. I'm not saying that a piece of off the shelf CF pipe won't work for you, but unless you have the specs modeled for that particular layup and mix, then there's no real way of knowing what you're getting. It's like saying you're going to build your house out of stone - ok, what stone? How? How thick? etc etc.

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  • gellfex
    replied
    Originally posted by garyhlucas View Post
    Being a sailor myself I’d go carbon fiber in a heartbeat. Even a few extra lbs at the top of a mast on an unballasted hull will likely have a big effect and losing weight up there is very desireable.
    I agree. I found this table of comparison, it makes a strong case for carbon.

    Carbon Fiber vs Aluminum Measured
    Measurement Carbon Fiber Aluminum
    Modulus of elasticity (E) GPa 70 68.9
    Tensile strength (σ) MPa 1035 450
    Density (ρ) g/cm3 1.6 2.7
    Specific stiffness (E/ρ) 43.8 25.6

    EDIT: crap! why won't they let me even hand format a table to be readable!

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  • garyhlucas
    replied
    Being a sailor myself I’d go carbon fiber in a heartbeat. Even a few extra lbs at the top of a mast on an unballasted hull will likely have a big effect and losing weight up there is very desireable.

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  • elf
    replied
    Originally posted by BCRider View Post

    I think you also missed the part where it's only 3/4" in diameter. A wood mast of that size simply wouldn't stand up and would be far more flexible in the wind.

    Gelfix, from the sounds of the communiques on the carbon option it sounds like stainless tubing will end up the winner. And that would not be the end of the world. Probably a couple of pounds heavier than the aluminium option? And maybe a bit under that?
    But it floats

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  • gellfex
    replied
    Originally posted by BCRider View Post

    I think you also missed the part where it's only 3/4" in diameter. A wood mast of that size simply wouldn't stand up and would be far more flexible in the wind.

    Gelfix, from the sounds of the communiques on the carbon option it sounds like stainless tubing will end up the winner. And that would not be the end of the world. Probably a couple of pounds heavier than the aluminium option? And maybe a bit under that?
    Well, considering the 6061 spar is 2/3 of a lb, a few lbs would be a lot! Actually, relative density is 2.8 to 8 g/cm3, so a SS spar would be 1.88 lb. No, not the end of the world, but not optimum. The tensile strength of the steel is not quite 2x that of AL, so losing wall thickness seems counterproductive, unless the way SS reacts to this sort of stress is different from AL. Would the extra lb up top be dramatic to the performance? I guess it's hard to see how directly, but the whole rig is so light it's still worrisome.

    Leave a comment:

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