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Thread: Re-building my Ketch Tonga (1960)

  1. #351
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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    Wonderful Nick, here we come exactly to the point! My idea was to laminate carbon-fibers between the 2 last layers of plywood to replace the original galvi-sheet that went all around my stern, have the woven carbon-fibers opened up just right for the size of the bolts to go through, and have the head of the bolts sitting inside the last layer of plywood. I would filler around the boltheads to get a flat surface, and the fibreglass with Epoxy goes over it. Like this no water can come in by the bolts, and if there should be a problem with the bolts one day it's easy to sort out.
    fair winds, Dody
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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    thx for the info dody. worried about another cold winter for you. that is a nice latitude but nj gets snow and slush frisco doesn't, altho they get lots of fog. i am at 30.29 lat and rarely snows or freezes. summers can be brutal tho. which chain plate came loose on your trip to portugal? your chain plate you have shown is beautiful and stout looking!

    jim

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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    Quote Originally Posted by Dody View Post
    Wonderful Nick, here we come exactly to the point! My idea was to laminate carbon-fibers between the 2 last layers of plywood to replace the original galvi-sheet that went all around my stern, have the woven carbon-fibers opened up just right for the size of the bolts to go through, and have the head of the bolts sitting inside the last layer of plywood. I would filler around the boltheads to get a flat surface, and the fibreglass with Epoxy goes over it. Like this no water can come in by the bolts, and if there should be a problem with the bolts one day it's easy to sort out.
    Carbon fibre does not like bolts.
    Until engineers got their heads round the material masts failed where stuff was bolted on.

    Why not bring the rovings up above deck in loops over a sleeve to create the eyes that the stays shackle to. So the rovings go over the loop one side, under the counter over the poop the other and so on.
    Rather than carbon, you might look at the properties and workability of aramid fibres as well.
    It really is quite difficult to build an ugly wooden boat.

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  4. #354
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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    Quote Originally Posted by Peerie Maa View Post
    Carbon fibre does not like bolts.
    Until engineers got their heads round the material masts failed where stuff was bolted on.

    Why not bring the rovings up above deck in loops over a sleeve to create the eyes that the stays shackle to. So the rovings go over the loop one side, under the counter over the poop the other and so on.
    Rather than carbon, you might look at the properties and workability of aramid fibres as well.
    Ah, good point with carbon and bolts! Might not be such a good idea then with carbon. Aramid (is that the same as Kevlar?) ... Fibreglass ... there must be something on the market nowadays which could be better suitable! Guess I've got to do some serious research here!!!

    With the loops and sleeve-system I have to admit that it might look good but it's impossible to find out what's going on inside. Old-style chainplates I can inspect, instantly see if something needs to be done and sort it out. Thus I prefer having proper old-time chainplates, even if they are mounted inside and held with bolts as described. I still will never be able to notice, if the material - which ever it will be in the end - between the plywood fails. But if it fails, there is first of all still the visible chainplate to hold my sticks up, and there will be some kind of signs indicating something is not good. Hopefully!

    On the other hand, some ships have such tiny chainplates for their size which makes me wonder if this re-inforcing with fibres is necessary at all. Still, it makes me feel better, that's for sure!
    fair winds, Dody
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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    Quote Originally Posted by Dody View Post
    Ah, good point with carbon and bolts! Might not be such a good idea then with carbon. Aramid (is that the same as Kevlar?) ... Fibreglass ... there must be something on the market nowadays which could be better suitable! Guess I've got to do some serious research here!!!

    With the loops and sleeve-system I have to admit that it might look good but it's impossible to find out what's going on inside. Old-style chainplates I can inspect, instantly see if something needs to be done and sort it out. Thus I prefer having proper old-time chainplates, even if they are mounted inside and held with bolts as described. I still will never be able to notice, if the material - which ever it will be in the end - between the plywood fails. But if it fails, there is first of all still the visible chainplate to hold my sticks up, and there will be some kind of signs indicating something is not good. Hopefully!

    On the other hand, some ships have such tiny chainplates for their size which makes me wonder if this re-inforcing with fibres is necessary at all. Still, it makes me feel better, that's for sure!
    Over engineer the strop. What is there to fail?
    You won't be inspecting the ply under the glass, nor will you be inspecting the glass either. You wont be taking the chain plated off to see if the bolts are fretting the hull that they bolt to.
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    The thread seems to have moved on a bit from planes,so I might be a bit late with this.The images are of my fairly old wooden rebate plane and shows the bevel down geometry and it also shows the skew of the plane iron,which used to be fairly common as it gave more of a slicing cut than the abruptness of a square edge coming into contact with the wood.







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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    Quote Originally Posted by MADOC1 View Post
    thx for the info dody. worried about another cold winter for you. that is a nice latitude but nj gets snow and slush frisco doesn't, altho they get lots of fog. i am at 30.29 lat and rarely snows or freezes. summers can be brutal tho. which chain plate came loose on your trip to portugal? your chain plate you have shown is beautiful and stout looking!

    jim
    I think then Frisco will be much closer to the climate here. Nice not having cold winters, but working outside when it is brutal hot as you describe must be a real challenge too.

    Thanks! It actually didn't come loose, it broke. The day before I left Spain in kind of a hurry. It was the chainplate for the backstay of the mainmast and upper shroud of the mizzen. Just in case you should be a bit bored right now and have nothing interesting to do I've been telling the story on this thread. Starts with post no. 161 on page 5. But, hang on, not that you might think I might think my story is interesting !!!
    fair winds, Dody
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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    Quote Originally Posted by John Meachen View Post
    The thread seems to have moved on a bit from planes,so I might be a bit late with this.The images are of my fairly old wooden rebate plane and shows the bevel down geometry and it also shows the skew of the plane iron,which used to be fairly common as it gave more of a slicing cut than the abruptness of a square edge coming into contact with the wood.






    That's a very interesting plane you've got there, thank you for posting the pictures John!
    fair winds, Dody
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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    Quote Originally Posted by Peerie Maa View Post
    Over engineer the strop. What is there to fail?
    You won't be inspecting the ply under the glass, nor will you be inspecting the glass either. You wont be taking the chain plated off to see if the bolts are fretting the hull that they bolt to.
    It's true, I won't take the chainplates off. But I will be pulling the bolts in 10 or 12-year intervals together with the replacement of the rigging-wire and bolts and splitpins. I've seen far too many mast-failures in my life to risk anything getting even near it. The trouble is that it's never just a clean thing and the stick has jumped over the side and is gone. It's always a big dangerous mess with lots of damage everywhere, hardly ever in nice weather and usually far away from land. And once you've jury-rigged something up and managed to arrive somewhere the next trouble starts to get hold of a replacement somehow because they are not laying around everywhere just waiting for you. Even though I had ordered brand new masts and booms, from start to delivery took 9 months.

    Nick, I don't know what is there to fail. It is a way of building that is done for a few years only. Time will show how reliable it really is. We've all seen inventions and products come and disappear for one reason or another.
    We all know that Epoxy disintegrates with UV exposure. With this system, the fibres have to be glued in place with Epoxy. Which needs to be painted regularly to be protected. There might be some bigger scratches that go unnoticed or for whichever reason you are away and can't take care of it.
    Yes, they say these fibres are super-strong. But how do they react to chafe? What if a sharp object falls down on it?

    I know what happens with steel and stainless if it is without paint, and I know what happens with stainless or steel concerning chafe or when a sharp object falls onto it. I can visualize and understand and know what to expect from both these materials. I know what a bolt does and what it doesn't and what I can expect it to do. With fibers I can't. This is why I prefer not to use this method for the chainplates.
    Last edited by Dody; 10-01-2017 at 04:19 PM.
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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    Quote Originally Posted by Dody View Post
    It's true, I won't take the chainplates off. But I will be pulling the bolts in 10 or 12-year intervals together with the replacement of the rigging-wire and bolts and splitpins. I've seen far too many mast-failures in my life to risk anything getting even near it. The trouble is that it's never a clean thing and the stick is gone. It's always a big dangerous mess with lots of damage everywhere, hardly ever in nice weather and usually far away from land. And once you've jury-rigged something up and managed to arrive somewhere the next trouble starts to get hold of a replacement somehow because they are not laying around everywhere just waiting for you. Even though I had ordered brand new masts and booms, from start to delivery took 9 months.

    And Nick, I don't know what is there to fail. It is a way of building that is done for a few years only. Time will show how reliable it really is. We've all seen inventions and products come and disappear for one reason or another.
    We all know that Epoxy disintegrates with UV exposure. With this system, the fibres have to be glued in place with Epoxy. Which needs to be painted regularly to be protected. There might be some bigger scratches that go unnoticed or for whichever reason you are away and can't take care of it.
    Yes, they say these fibres are super-strong. But how do they react to chafe? What if a sharp object falls down on it?

    I know what happens with steel and stainless if it is without paint, and I know what happens with stainless or steel concerning chafe or when a sharp object falls onto it. I can visualize and understand and know what to expect from both these materials. With fibers I can't. This is why I prefer not to use this method for the chainplates.
    I'll not labour the point, so this will be the last on this topic.
    You are planning on using epoxy carbon fibre in the strop, and then bolting to the structure that contains it. A system for transferring load between dissimilar materials requiring careful design of the interfaces. This to ensure the even transfer of the loads so as not to create a hard spot of one highly loaded bolt next to one less highly loaded. Said loads being in shear and compression on surface of the holes in the hull composite.
    By using an epoxy lay up the loads go straight from rigging wire into the hull.
    Your only worry is protecting the lay up from chafe and UV light. An appropriate paint or thin metal cover will do that.
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    Quote Originally Posted by Peerie Maa View Post
    I'll not labour the point, so this will be the last on this topic.
    You are planning on using epoxy carbon fibre in the strop, and then bolting to the structure that contains it. A system for transferring load between dissimilar materials requiring careful design of the interfaces. This to ensure the even transfer of the loads so as not to create a hard spot of one highly loaded bolt next to one less highly loaded. Said loads being in shear and compression on surface of the holes in the hull composite.
    By using an epoxy lay up the loads go straight from rigging wire into the hull.
    Your only worry is protecting the lay up from chafe and UV light. An appropriate paint or thin metal cover will do that.
    Hmmmm ... loads for me to think about. You are a great help Nick, thank you so much for your thinking and letting me know!
    fair winds, Dody
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    Quote Originally Posted by DeniseO30 View Post
    I have the same problem, keeping the edge square on my Stanley #93

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    Denise, how are you doing your sharpening - by hand or with a honing-guide? I'm by far too inexperienced, that's why I'm using a honing-guide and with this it's really easy to get the edge square. The only thing you really have to be very particular about is making sure it's clamped perfectly straight in your guide. But whom am I telling that, you are the expert of course!!!

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    Ah, it just came to me that I forgot to tell you the weirdest thing about this "emergency"-chainplate, something that still puzzles and surprises me, especially that it survived Hurricane Bill on the windward side: what I was using to attach this chainplate to the hull were just simple woodscrews with a hexagonal head! Sure, they do have a shoulder, and they are working in sheer. But it's still a complete mystery for me that they proved actually to be up for the job. An outcome I didn't expect at all! But then, why shouldn't I be lucky once in a while? However, I'm not planning to repeat experiments like this!

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    Quote Originally Posted by Dody View Post
    Ah, it just came to me that I forgot to tell you the weirdest thing about this "emergency"-chainplate, something that still puzzles and surprises me, especially that it survived Hurricane Bill on the windward side: what I was using to attach this chainplate to the hull were just simple woodscrews with a hexagonal head! Sure, they do have a shoulder, and they are working in sheer. But it's still a complete mystery for me that they proved actually to be up for the job. An outcome I didn't expect at all! But then, why shouldn't I be lucky once in a while? However, I'm not planning to repeat experiments like this!

    Sent from my SM-G900FD using Tapatalk
    The reason that many Fasteners in sheer work better than a few is because there's safety in numbers and they distribute the load over a large surface area. another example would be the top of a Mainsail that is sandwiched in between usually two aluminum plates. Still another example would be bridge and girder rivet construction

    I use the water wheel to Hollow Grind my plane irons and chisels and then I hone them on a diamond honing plate sometimes on a wet stone. You inspired me to use even finer grit Stones which I do have and they make the difference! I have a roller guide as mentioned earlier I don't use it however you ever it only takes a few minutes hone on the diamond sharpeners

    Oh! Hex head wood screws I believe are generally called lag screws

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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    Quote Originally Posted by DeniseO30 View Post
    The reason that many Fasteners in sheer work better than a few is because there's safety in numbers and they distribute the load over a large surface area. another example would be the top of a Mainsail that is sandwiched in between usually two aluminum plates. Still another example would be bridge and girder rivet construction

    I use the water wheel to Hollow Grind my plane irons and chisels and then I hone them on a diamond honing plate sometimes on a wet stone. You inspired me to use even finer grit Stones which I do have and they make the difference! I have a roller guide as mentioned earlier I don't use it however you ever it only takes a few minutes hone on the diamond sharpeners

    Oh! Hex head wood screws I believe are generally called lag screws

    Sent from my LG-M430 using Tapatalk
    That's correct Denise, but they were no bolts with a nut on the other end, just screwed into the planks. OK, I got them just the right size so they wouldn't come out on the other side of the plank but get to the end of it. Which means the thin tip of the screw (lag screw, sorry, you're right of course!) at the outside end of the plank does nothing ....
    fair winds, Dody
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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    Quote Originally Posted by Dody View Post
    That's correct Denise, but they were no bolts with a nut on the other end, just screwed into the planks. OK, I got them just the right size so they wouldn't come out on the other side of the plank but get to the end of it. Which means the thin tip of the screw (lag screw, sorry, you're right of course!) at the outside end of the plank does nothing ....
    When bolting to wood, you are not squeezing the wood to create friction as with time the wood will crush and the friction disappears. Denise was referring to the thickness of the bolt and of the wood providing an area for the bolt to thrust against across the bolts length. The shear in the bolt is between the wood and metal, the work is done by the area in compression through the thickness of the wood where the bolt is in contact with it.
    Two skinny a bolt and it will act like a log splitter riving through the wood.
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    OK, did some more research. Carbon is a conductor and reacts with SS and all kind of metals, SS can actually destroy the carbon. Now this not what I want.

    Aramid to the contrary is non conductive. I found an article where there was stated "strong acids can cause substantial loss of strength" - which in theory should not be an issue where I intend to use it. It also said in this article that "the aromatic nature of para-aramid is responsible for oxidative reactions when exposed to UV-light, that leads to a change in colour and loss of some strength" which means it needs to be protected from UV - again no issue where and how I would like to use it. Now there is one thing they stated under thermal properties "Aramid fibres do not melt in the conventional sense but decompose simultaneously" - I assume this decomposition-process only happens in connection with heat!???

    The whole article can be found here http://www.aramid.eu/characteristics.html and I do have the impression that Aramid would be quite suitable.

    Now on to the next subject: how I can get the material to spread the loads evenly between the bolts ...
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    Quote Originally Posted by Dody View Post
    OK, did some more research. Carbon is a conductor and reacts with SS and all kind of metals, SS can actually destroy the carbon. Now this not what I want.

    Aramid to the contrary is non conductive. I found an article where there was stated "strong acids can cause substantial loss of strength" - which in theory should not be an issue where I intend to use it. It also said in this article that "the aromatic nature of para-aramid is responsible for oxidative reactions when exposed to UV-light, that leads to a change in colour and loss of some strength" which means it needs to be protected from UV - again no issue where and how I would like to use it. Now there is one thing they stated under thermal properties "Aramid fibres do not melt in the conventional sense but decompose simultaneously" - I assume this decomposition-process only happens in connection with heat!???

    The whole article can be found here http://www.aramid.eu/characteristics.html and I do have the impression that Aramid would be quite suitable.

    Now on to the next subject: how I can get the material to spread the loads evenly between the bolts ...
    Dody, if I'm interpreting correctly the original chainplates we're pretty nicely made, also adjustable, I think if you reproduce or enlarge the plate that bolts to the hull or frame you would be able to sleep at night.

    Just my opinion, do the through bolts, call it a day. If seeing them on the outside causes you to lose sleep then maybe bronze would be better than stainless?





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    Quote Originally Posted by DeniseO30 View Post
    Dody, if I'm interpreting correctly the original chainplates we're pretty nicely made, also adjustable, I think if you reproduce or enlarge the plate that bolts to the hull or frame you would be able to sleep at night.

    Just my opinion, do the through bolts, call it a day. If seeing them on the outside causes you to lose sleep then maybe bronze would be better than stainless?





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    Sorry Denise, sometimes I'm terrible with explaining things!
    The original chainplates were not adjustable. They were clever, but not nicely made. Maybe I manage to explain with a picture from what is left at the moment - will have to explain in 2 parts otherwise Tapatalk mixes it all up:


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    Quote Originally Posted by Dody View Post
    Sorry Denise, sometimes I'm terrible with explaining things!
    The original chainplates were not adjustable. They were clever, but not nicely made. Maybe I manage to explain with a picture from what is left at the moment - will have to explain in 2 parts otherwise Tapatalk mixes it all up:


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    What you see in the first picture is what is left of a galvi sheet. This was for the shroud of the mizzen and went all around the hull to the chainplate on the starboardside. A similar galvi-sheet, only about 75 cm wide, went in an angle of maybe 30° from up there all around the boat again to the starboardside. These were welded to what was originally sticking out. What broke was the weld.

    Rightly so, Nick and Rumars suggested to use a modern composite chainplate instead. For various reasons I don't want to have carbon-fibre chainplates on deck but stainless instead. On the other hand I am looking for a material I can replace the original galvi-sheet with, because this is a very clever and strong way of doing it.

    Shure, I could just copy the old system and install a new galvi-sheet. Right now I'm trying to find a way to use Aramid instead in combination with something similar to my "emergency" chainplate. Serving a double-purpose.

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    Last edited by Dody; 10-02-2017 at 10:26 AM.
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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    oh, my bad! This what I was looking at.

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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    It that were bronze $$$ (may as well be gold) she be good for 100 years! I recently read that bronze can be welded

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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    Quote Originally Posted by DeniseO30 View Post
    oh, my bad! This what I was looking at.

    Quote Originally Posted by DeniseO30 View Post
    It that were bronze $$$ (may as well be gold) she be good for 100 years! I recently read that bronze can be welded

    Lol***, I see, now I understand !!! Well, with these I'm not worried at all. I can keep using them or I do something else, but this I can decide about the moment things are going back in. The other ones, they are the bit I've got to decide about before I start laminating up the hull and that's why I'm trying to work out a clever system now.
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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    Quote Originally Posted by Dody View Post
    What you see in the first picture is what is left of a galvi sheet. This was for the shroud of the mizzen and went all around the hull to the chainplate on the starboardside. A similar galvi-sheet, only about 75 cm wide, went in an angle of maybe 30° from up there all around the boat again to the starboardside. These were welded to what was originally sticking out. What broke was the weld.

    Rightly so, Nick and Rumars suggested to use a modern composite chainplate instead. For various reasons I don't want to have carbon-fibre chainplates on deck but stainless instead. On the other hand I am looking for a material I can replace the original galvi-sheet with, because this is a very clever and strong way of doing it.

    Shure, I could just copy the old system and install a new galvi-sheet. Right now I'm trying to find a way to use Aramid instead in combination with something similar to my "emergency" chainplate. Serving a double-purpose.

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    Welding galvo is a no no, the zinc creates havoc. It would have been better to rivet it.
    As you are determined to keep the stainless chain plates I would use an appropriate grade of stainless steel sheet.
    If you want to laminate up aramid reinforced plastic designing the bolt holes could be tricky. The laminate could just tear along the perforations. I would look at laying the aramid up around dummy bolts of hard wood, perhaps in grooves routered into the hull plank to account for the bulking up of the rovings as they turn around the bolts. Then after clean up you can bore holes in the wood dowels into which the chain plate bolts may be fitted.
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    Quote Originally Posted by Peerie Maa View Post
    Welding galvo is a no no, the zinc creates havoc. It would have been better to rivet it.
    As you are determined to keep the stainless chain plates I would use an appropriate grade of stainless steel sheet.
    I agree, and this is the reason it failed. OK, some 54 (or maybe less) years later, but still. That's actually not a bad idea using stainless sheets as there wouldn't be any problem with the welds. The only thing problematic then is, that stainless doesn't like being sealed up, which in this case it would be.


    Quote Originally Posted by Peerie Maa View Post
    If you want to laminate up aramid reinforced plastic designing the bolt holes could be tricky. The laminate could just tear along the perforations. I would look at laying the aramid up around dummy bolts of hard wood, perhaps in grooves routered into the hull plank to account for the bulking up of the rovings as they turn around the bolts. Then after clean up you can bore holes in the wood dowels into which the chain plate bolts may be fitted.
    Good point! My thinking-process started with "just" a bunch of fibres as they do with the composite chainplates, sticking PVC-tubing the same size as the bolts in the boltholes as some simulation of the bolts and to have something to wrap the fibres around when going from one side to the other and back - till I came to the problem you mention, the bulking of the rovings. And also the question how many of these fibres would be necessary for each bolt.
    I stopped at that point and asked myself how this would be if I use woven Aramid? With all the woven fibres I've been working till now, it was possible to just carfully push the material aside to make a hole without damaging the material. Like this it wouldn't bulk and the Epoxy doesn't stick to the PVC-piping when laminating. Of course it wouldn't do to use one layer only, but at least 2 or more.
    Concerning the laminate tearing along the perforations, yes, very good point! Hm. It would be sandwiched between plywood epoxy-filler-glued, which might help a bit, but the danger is still there. Hm .... hm .... hmmmmm ... got to do heaps more thinking about this!!!
    fair winds, Dody
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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    ^ There are stainless steels compatible with being encapsulated in wood. After all your bolts will be buried.

    The transfer of the load from the bolts to the wood and rovings is like pushing a (very) blunt blade through the wood and layup, which is why I am pushing for winding the rovings around the bolts as if you were making a skein of wool. If you use a cloth, the cross ways rovings will be doing no work over most of the strop, and have to transfer the load sideways through the resin into the longitudinal fibres at the bolts.
    If you are making a lifting strop out of webbing, you do not poke a hole in the webbing, you bend it round and sew a loop.
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    Quote Originally Posted by Peerie Maa View Post
    ^ There are stainless steels compatible with being encapsulated in wood. After all your bolts will be buried.

    The transfer of the load from the bolts to the wood and rovings is like pushing a (very) blunt blade through the wood and layup, which is why I am pushing for winding the rovings around the bolts as if you were making a skein of wool. If you use a cloth, the cross ways rovings will be doing no work over most of the strop, and have to transfer the load sideways through the resin into the longitudinal fibres at the bolts.
    If you are making a lifting strop out of webbing, you do not poke a hole in the webbing, you bend it round and sew a loop.
    Thank you so much Nick, this makes a lot of sense!!!
    fair winds, Dody
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    Quote Originally Posted by Dody View Post
    Thank you so much Nick, this makes a lot of sense!!!
    Dody, if you do use a composite instead of metal why not at least use bronze bolts? Also realize, you're going to use epoxy whatever fabric you choose and it's going to be very well bonded to the wood on both sides. I don't see any need to get into the science and engineering of sheer strength of all this. I mean like you said the old ones lasted over 50 years and they only failed because of water intrusion apparently. Jus saying....

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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    Thank you so much Denise! I am, to be honest, still hoping to work out a way to use fibers instead of metal. What Nick says makes perfectly sense to me, but I am still wondering if we might have overlooked something that would still make it possible. Using fibers would make everything much more easy. I wouldn't have to struggle for a solution how to properly attach the diagonal plywood-strips to the metal during the curing-time of the Epoxy, I wouldn't have to ask Leandro to weld the sheets in place risking my boat catching fire and and and. You know how it is, people can be very stubborn a times and I can't say I'm an exception. Sorry for that, but I'm not a computer yet.

    I've done something today I actually wanted to avoid, I contacted my so-to-speak "twin-brother" to hear his opinion. I wanted to leave him in peace as he just came out of a very tough surgery and, although still in recovery mode, is already back and off to get his business sorted. He's been working with all these fibers and any kind of resins one can think of (nearly) all his life, for many years he's been a professional boatbuilder (in carbon and whatever) and, since he came back to OZ in 2003 I think, he's into solutions for campervans - in fiberglass of course. No idea when he will have worked something out, but he was happy to dig into it when I asked him today. He might confirm what Nick made me aware of, he might come up with a completely different idea, or he might find a way to use fibers. Whatever the outcome I'll let you know.

    Now, Denise, there is something that's confusing me from what you were mentioning, the idea to use bronze bolts. I might be completely wrong, so, please, correct me!!! I always thought that it is best in applications where one has to deal with shear-forces to use identical metals for the fitting and the bolts, and somewhere in my life people made me even understand that the bolt has to be stronger than the fitting in case it's not possible to have them both from the same material. As far as I know bronze is quite a soft material, and stainless is pretty hard. Now here you are, being certainly the more experienced as you've had the fortune to be involved in all this for all your life, while I've spent the majority of my life working in an office with unfortunately hardly anything of practical stuff going on till I moved aboard. Please, could you explain to me what is your idea behind using bronze bolts?

    Thank you heaps in advance!!!
    Last edited by Dody; 10-03-2017 at 04:01 PM.
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    Quote Originally Posted by Dody View Post
    Thank you so much Denise! I am, to be honest, still hoping to work out a way to use fibers instead of metal. What Nick says makes perfectly sense to me, but I am still wondering if we might have overlooked something that would still make it possible. Using fibers would make everything much more easy. I wouldn't have to struggle for a solution how to properly attach the diagonal plywood-strips to the metal during the curing-time of the Epoxy, I wouldn't have to ask Leandro to weld the sheets in place risking my boat catching fire and and and. You know how it is, people can be very stubborn a times and I can't say I'm an exception. Sorry for that, but I'm not a computer yet.

    I've done something today I actually wanted to avoid, I contacted my so-to-speak "twin-brother" to hear his opinion. I wanted to leave him in peace as he just came out of a very tough surgery and, although still in recovery mode, is already back and off to get his business sorted. He's been working with all these fibers and any kind of resins one can think of (nearly) all his life, for many years he's been a professional boatbuilder (in carbon and whatever) and, since he came back to OZ in 2003 I think, he's into solutions for campervans - in fiberglass of course. No idea when he will have worked something out, but he was happy to dig into it when I asked him today. He might confirm what Nick made me aware of, he might come up with a completely different idea, or he might find a way to use fibers. Whatever the outcome I'll let you know.

    Now, Denise, there is something that's confusing me from what you were mentioning, the idea to use bronze bolts. I might be completely wrong, so, please, correct me!!! I always thought that it is best in applications where one has to deal with shear-forces to use identical metals for the fitting and the bolts, and somewhere in my life people made me even understand that the bolt has to be stronger than the fitting in case it's not possible to have them both from the same material. As far as I know bronze is quite a soft material, and stainless is pretty hard. Now here you are, being certainly the more experienced as you've had the fortune to be involved in all this for all your life, while I've spent the majority of my life working in an office with unfortunately hardly anything of practical stuff going on till I moved aboard. Please, could you explain to me what is your idea behind using bronze bolts?

    Thank you heaps in advance!!!
    Oh ur welcome, I'm not pretending to all knowledgeable in this. I thought a long skinny "strap" of bronze would work but then I realized the inner hull planks have spacing so stainless may actually last longer then most of us! I kind of do like the old school, long strap to the hull and up through the rail with a slide over flange and sealer.

    http://www.briontoss.com/spartalk/printthread.php?t=2634




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    Last edited by DeniseO30; 10-03-2017 at 09:12 PM.
    Denise, Bristol PA, Oday30, Anchor Yacht Club, On tidal Delaware River. my current project; http://forum.woodenboat.com/showthre...0-Ducker-Resto

  31. #381
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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    We'll leave the chainplate-question for a moment to give my "twin-brother" some time and space to work out a soulution for me. He's started working on it as much as his very limited time permits and, like myself, he wants to get it right the first time. Will give you an update as soon as we've got some results.

    Meanwhile on Tonga ... still suffering heaps with my left shoulder so visited a Physiotherapist on Friday for the first of apparently many more sessions to come. Well, that's what you get if you leave it too late ...

    Still, I just couldn't see the nice weather go by unsused. Promising myself to go slow and gentle and just do a little, soon - of course - found me throwing all the good intentions overboard fighting to get nails out in the most awkward positions and things getting worse.

    But, got the batten on top of the beamshelf out





    still a bit more cleanup needed



    and started with the replacement. Still feel a bit sorry for all the wood going to waste in planing down from 40 mm to 21 mm, but I didn't have a thinner plank (by the way, carrying this one to have it cut into 3 by Albertino caused me all this misery with my shoulder).



    and ready for a test-fit and last tiny adjustments

    fair winds, Dody
    "They did not know it was impossible so they did it" - Mark Twain
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  32. #382
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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    I hope your shoulder heals soon Dody. Those strains can have a way of sticking around for a very long time, especially if we don't give them time to heal. I've had a sore elbow for over a year now that I suspect came from too much sanding. I keep meaning to have it checked out... Must remember to do that when I get back!
    - Chris

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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    Thank you Chris! Same with me, I was struggling a little bit with it for over a year, and then this plank came along. My own fault, left it too long. As it turns out, I've got to turn up for physiotherapy every day now. Of course, it's inconvenient but I can live with it. What I can't live with at the moment is that I'm not supposed to lift or touch anything but sit there with a hot water bottle on my shoulder the rest of the day and just wait, seeing the nice weather go by ...
    Well, they say something like "boatbuilding is a work of patience", guess I start to grasp what they mean by it . However, there's still heaps of research and reading to be done, maybe this is a good option to keep me busy right now.
    fair winds, Dody
    "They did not know it was impossible so they did it" - Mark Twain
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  34. #384
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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    sorry to hear about your shoulder. is it your dominate side? if not then i guess you could still work on sharpening. how long do you have to keep treating it? bummer.

    jim

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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    Thank you so much jim! Well, in my case I can use both sides nearly equal, hardly any difference even when writing. And, actually really happy that all the sharpening is done for the moment - if we don't mention the chisel I hit a nail with the other day with a little bit too much force lol*! Surprisingly enough, I can notice a really significant difference with how long they manage to hold their blade after my session with the japanese water stones. Sure, I was hoping there would be a difference. But this is a big one and I'm very very happy about it!

    Well, initially he was talking about 2 entire weeks without moving a finger. We'll see how it goes. I had Friday, Monday and today, each 2 hour-sessions, and already down from 8 to 1 Ibuprofene and capable to turn my head towards the left shoulder without crying out in agony. Would be nice if progress should keep on going like this ... fingers crossed !!!
    fair winds, Dody
    "They did not know it was impossible so they did it" - Mark Twain
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