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

  1. #36
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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    Quote Originally Posted by MN Dave View Post
    I am back to urging caution based on insufficient information. This should be thought through carefully. My inexpert opinion is that there is so much structure supporting a very substantial fiberglass shell on this boat that you could live without much of one or the other. 3 layers (18mm total) of plywood is probably more than adequate even if it is not as strong as the original 10 mm of glass.

    I see a lot of thickness numbers here, some plans, some historical and some measured. There seems to be a discrepancy between the measured fiberglass thickness and the originally reported 2 layers of cloth.
    Dave, I absolutely agree with you. There are so many factors to take into account. As she's an old boat, no manufacturer will give you any definite answers if you ask them about their products. She is a amateur-built to own designs, so no shipyard will give you an answer. The only thing I can do is guesswork. For this guesswork I am looking for as many ideas, suggestions and exchanges I can get, because overlooking some important point can mean the failure of the whole project or my ship breaking up in mid-ocean.

    My original idea was to estimate the strength of what is there, find out what would be more or less equal with the materials I am going to use and add a little bit to it for safety.

    But it's not as simple as that. Obviously. So, the more information and ideas I can get the less I will overlook.

    The guy who built her added more fibreglass after she was launched. I am sure he did that for a reason. To know more about this I measured and weighted the pieces which can give me, us, another indication about the situation.
    Last edited by Dody; 06-28-2017 at 07:27 AM.

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

    Quote Originally Posted by Dody View Post
    ...
    The Fibreglass under the waterline was between 9 and 11 mm, above the waterline between 6 and 7 mm.
    ...

    Just for fun I've calculated the weight of 1 m2 of the fibreglass I took off and the result was 5 KG for 1 m2, this is without the 4 mm plywood.
    Asuming the calculated 5kg/sqm are from the topsides with a thickness of 6-7mm there must be a lot of filler and paint there. 600g/sqm CSM/rowing complex handlaid with polyester would give around 1.5mm thickness and a weight of around 2kg. 450g/sqm CSM would give around 1mm thickness with a weight of around 1.5kg. 600g/sqm fabric would give 0.6mm thickness and 1kg of weight.
    Depending on the used type of fibre I come to a result of at least 8kg/sqm for a thickness of 6mm. For 10mm that is at least 13kg/sqm.
    Considering the poor adhesion to the plywood I don't think that the fiberglass contributed much to the strenght of the boat.

    Dody if you look at the torn edge of the fiberglass it should be pretty evident what type of fiber whas used (woven or CSM) and sometimes even the layers are evident. Smack the edge with a hammer to shatter the resin if it's not clear.

  3. #38
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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    I just did some tests. It is a bit difficult to say as, the moment I bash it with the hammer, the edge kind of changes into a bunch of fibers of all different kind.

    To me, from inside to outside, it looks like:
    1. one layer of woven cloth (not the rough kind of woven but the finer woven stuff), which was directly on the plywood
    2. one layer of filler, varying, between 0.5 and 2 mm thick
    3. one layer of woven cloth like above
    4. several layers of CSM, thickness varying, between 2 - 3 mm above the waterline and about 7 mm unter the waterline
    5. one or 2 layers of cloth like above (this is kind of difficult to say, but I have the impression it is 2 layers)
    6. some more filler and the paint

  4. #39
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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    Weird setup. Points 1-3 were the original layup presented in the article. 4-5 aded at a later point but why is anyones guess. Could be there was print-through from the plywood strips (starved horse effect), or aded abrasion resistance was desired, or sheer paranoia, etc.

    Dody if you want you could buy Dave Gerr book Elements of boat strenght. The book is written for amateurs and has scantling rules so you could check out your boat. Or obtain some official scantling rule like GL or LR or RINA to check against that.

  5. #40
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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    Haaaahhhahaaaahhhh, what a coincidence!!!! I've just completed my order, got the confirmation, and 3 minutes later the info by email that you posted on this thread !!!

    Right. I've just ordered 3 books: "The Elements of Boat Strength: for Builders, Designers and Owners" by Dave Gerr, "The boat Data-Book" by Ian Nicholson and "Skene's Elements of Yacht Design: The original Edition of the Classic Book on Yacht Design" by Norman Locke Skene.

    I hope they don't take too long to arrive here, and I hope I will find some answers by reading them!

    When I bought her in 1996, I asked him this question. It is too long ago now, but I remember there was something like too much flexibility in the hull or the hull not stiff enough or so, which he didn't feel comfortable with.

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

    My new books still haven't arrived, but reading and most of the time understanding the "Boatbuilding Manual", and getting on with my deck still keeps me more than busy.

    I've got something I am wondering about for a long time already, and still haven't been able to find an answer. What kind of thing is this, and what was or is the purpose of it? There were maybe 15 or more of them on each side. Every one a bit different to the other. For being old chainplates some of them were in very strange places. Giving additional strength to beamshelf, deck and frame maybe? Very strange is, that they were cut off - or ended - just below the last two layers of my old plywood-deck. However, I replace them everywhere (and also where they were not installed) with plywood-knees, bolted, screwed and sikaglued to the frames using the same boltholes, removing and replacing the spacing-wood to the frame where necessary.





  7. #42
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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    That is some weird construction inside your boat, and those bits of angle iron are no less weird than the timber framing.
    They could have been badly designed chainplates from an earlier rig, but otherwise no idea.
    It really is quite difficult to build an ugly wooden boat.

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  8. #43
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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    "some weird" Nick?
    This is the goofiest built vessel I have ever seen,outside of boats like hawaiian and faith etc.
    bruce

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

    I bet those are the original stanchions of the boat. They leaked (of course) so they were cut of and aditional ply put over the deck.

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

    Or even a structure to support a big shade cover? Their positions would help to understand.

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

    Stanchions ... of course, now it makes sense!!!!

    Just found some old photos. Looks like they have been chainplates in some places, stanchions in others before they added the new toerail. At least, what I can see in the old photos, they are in be the same places where I found these things.


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

    Quote Originally Posted by Peerie Maa View Post
    That is some weird construction inside your boat, and those bits of angle iron are no less weird than the timber framing.
    They could have been badly designed chainplates from an earlier rig, but otherwise no idea.
    Now you make me curious! Try to think away the nasty wood attached to the frame that was used to double up for having a flat surface, try to ignore that it's not cleaned up yet in the picture. What is left then is a sawn frame, beamshelf, and the triangle they used when the frames were made to keep their shape. I might be wrong, but in my opinion they left the triangles in place to double up as a knee for more strength. Certainly, I am far from having the experience all you guys have managed to achieve over the years, so this is probably why I can't see something wrong with it. Could you explain to me what is wrong with doing it like this?

    Maybe some more pics from the building-process in 1958 - 1960 and also from now can help:







    and from about 1 1/2 years ago (all the electric cables are removed by now, the support for the mainmast has been changed, she's got a proper carlin etc.:

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


  14. #49
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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    This
    even with the angle bar and its packing is wierd work for a shipwright, and the triangular filler in top of the built up bracket

    are also odd.
    Most shipwrights would have sourced grown crooks, or had a smith fabricate iron hanging knees.

    To be frank, it looks as though she has been completely re-decked by a cowboy builder. Possibly twice.


    That keel structure is a bit eccentric too.
    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

    She does look a bit like an early iteration of the Flyin Hawaian.

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

    Quote Originally Posted by Peerie Maa View Post
    This
    even with the angle bar and its packing is wierd work for a shipwright, and the triangular filler in top of the built up bracket are also odd.
    Most shipwrights would have sourced grown crooks, or had a smith fabricate iron hanging knees.

    To be frank, it looks as though she has been completely re-decked by a cowboy builder. Possibly twice.
    That keel structure is a bit eccentric too.
    Yes, I understand.

    What would you suggest how I can do it better?

    Now please, hundreds of times I've seen people with this puzzled look in their faces "I don't understand you, there are so many beautiful and fast plastic-boats on the market, why don't you just scrap her and buy one of them?
    Or: you will never get the money back you invest in this boat (well, I have no intentions to sell her anyway)
    Or: just take her lines, draw a new plan, built a copy of her and scrap what you've got
    Or: you will die here with your ship, this takes so long she will never float again

    Well, I love this ship, we've done a lot of sailing together, she is my home and she's always cared for me and saved my life in many ways. And now it's time for me to do something for her, what's wrong with that?

    As I said in the beginning I'm not a boatbuilder.

    Her deck was soft in places, I needed to find out what is happening under the surface. By this time I was in Nazaré/Portugal. People are allowed to work and live on their own boats in the yard, first major problem sorted. The climate is very agreeable nearly all year around to work on your boat and, a friend of mine, who is a fisherman, offered me to use his workshop to store my gear and my material. Some time later a workshop became available and since then I've got my own fishermen's workshop, a few meters from my boat, something which is very rare. All this made me decide to stay here to sort it all out.

    After cutting a square in the top layer I found plywood in a desintegrating state. I cut another square somewhere else, the same picture was looking at me. Right, the whole stuff has to come off and needs to be replaced.

    What made me start was the fact that the guy who built her was not a shipwright by profession and still managed to build her. Why should I not be able to learn on the go and do it? So, I started. I already had quite lot of tools and machines, but the collection kept growing and still does!

    Everybody else would have ripped the whole deck off first and then done a complete fresh start. I was scared it might be too much for me like this. So I started instead at the bow, 3 deckbeams at a time, first layer on and then opening up between the next 2 or 3 deckbeams, sorting out whatever I found bad on the go.

    Fortunate for me: most of the time the local shipwright for wooden fishingboats was around and helped me out tremendously with hints and tricks and sometimes even gave me a hand. To get a better understanding of the construction I had my "bible": Buehler's Backyard Boatbuilding, but also some other books to learn how to work with wood.

    Right now I'm 3 1/2 years in my project (minus 3 months when I was knocked out with a bad back), and I'm still enjoying it. Concerning the deck and stuff that needs replacing I'm aft of the cockpit now.

    Sure, I could cut all these triangles out again if this is not proper boatbuilding and not needed. On the other hand they do use knees bolted to deckbeams and frames on workboats, so they shouldn't be doing any harm. Also, they will be behind cupboards at some time later, nobody will see them. And it's great insofar as in the future I can run my electric cables with proper cable channels passing through these holes instead of the deckbeams and the bilge as it was before !
    Last edited by Dody; 07-10-2017 at 07:36 PM.

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

    Quote Originally Posted by Phil Y View Post
    She does look a bit like an early iteration of the Flyin Hawaian.
    Unfortunately I don't know where the design came from. The only thing I do know is that the plans were for an 11 m boat and when the guy who built her started to design his interior found out that it doesn't fit into 11 m, so he changed the plans to 14.50 m. Will try to dig up some photos of her in a bit more presentable state.

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

    Quote Originally Posted by Dody View Post
    Unfortunately I don't know where the design came from. The only thing I do know is that the plans were for an 11 m boat and when the guy who built her started to design his interior found out that it doesn't fit into 11 m, so he changed the plans to 14.50 m. Will try to dig up some photos of her in a bit more presentable state.
    My comment was a bit tongue in cheek. Flyin Hawaiian was a very bad home built boat which had a thread here. Your boat on the other hand, has an elegant and seaworthy shape to her, and has obviously proven herself as a capable ocean voyager over the years. Her construction seems very unconventional. I think it took us all a while to work out whether her for and aft hull timbers should be called planks or stringers. As such much of the conventional wisdom, some of it very conventional indeed, will not be much help to you. I'd say if you see methods on her which have worked, and/or methods which work on the local boats, then go for it. It might not be conventional, might not be Yot Kwality, but if it works, it's good. I admire your enthusiasm and tenacity.

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



    Hm, can't find what I'm looking for, the ones I've got on FB she's always too far away so hard for you to see, and not enough data-volume on my phone left to upload others. Maybe these two can do for the moment for underwater?


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

    Quote Originally Posted by Phil Y View Post
    My comment was a bit tongue in cheek. Flyin Hawaiian was a very bad home built boat which had a thread here. Your boat on the other hand, has an elegant and seaworthy shape to her, and has obviously proven herself as a capable ocean voyager over the years. Her construction seems very unconventional. I think it took us all a while to work out whether her for and aft hull timbers should be called planks or stringers. As such much of the conventional wisdom, some of it very conventional indeed, will not be much help to you. I'd say if you see methods on her which have worked, and/or methods which work on the local boats, then go for it. It might not be conventional, might not be Yot Kwality, but if it works, it's good. I admire your enthusiasm and tenacity.
    No worries Phil , didn't know about the Flyin Hawaiian anyways, and I don't care about Yotty-Quality. It's got to work, be practical, tough and waterresistant. Wouldn't mind if it's a tiny bit cozy and comfortable, but this doesn't take too much extra effort.
    Last edited by Dody; 07-10-2017 at 08:48 PM.

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

    Shes a beauty for sure.

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

    After reading about Anchorfast/Gripfast nails in Monel or Silikon Bronze in the "Boatbuilding Manual", but also in "The Harbourmaster called me today" (love his shed, it's awesome!!!) the idea struck me that once I've got the plywood Epoxy-Filler-glued in place, I will never again be able to get to the nails holding the planks to the frames (or however we might call them). Using Monel or Silikon Bronze I would (hopefully) never ever have to touch them again.

    I looked a bit around, I could get Anchorfast nails in Silikon Bronze, the max standard size would be 4.0 mm x 75 mm = 8 Gauge x 3 ". Possibly they would be able to have different sizes made, but I haven't asked yet.

    First question:

    Would I have to pull all the old nails out if I wanted to use Anchorfast nails, or can they stay in? And if they have to be pulled out, is there a trick without destroying the wood around the head? The old ones were galvi, and I don't know if this will cause a reaction. As far as I can see at the moment there would be space enough to just add the Anchorfast nails.

    Second question:

    I am getting a bit mixed up which size I would have to use. The local shipwright would have used galvi-nails, 90 mm long and (including the galvi) 3.9 mm thick which somehow looked right. The table on page 128 in my book ends with a plank-thickness of 1" (my - whatever we call them - are 30 mm thick which would be something like 1" plus 4.6 mm). In this book the nails should be 2" x .238" - which is much thicker but shorter.

    Third question:

    am I overlooking something?

    Thanks, Dody
    Last edited by Dody; 07-11-2017 at 01:14 PM.

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

    Quote Originally Posted by Dody View Post

    Fortunate for me: most of the time the local shipwright for wooden fishingboats was around and helped me out tremendously with hints and tricks and sometimes even gave me a hand. To get a better understanding of the construction I had my "bible": Buehler's Backyard Boatbuilding, but also some other books to learn how to work with wood.


    Sure, I could cut all these triangles out again if this is not proper boatbuilding and not needed. On the other hand they do use knees bolted to deckbeams and frames on workboats, so they shouldn't be doing any harm. Also, they will be behind cupboards at some time later, nobody will see them. And it's great insofar as in the future I can run my electric cables with proper cable channels passing through these holes instead of the deckbeams and the bilge as it was before !
    You are fortunate to have found a shipwright, it is what the boat needs.

    Those triangular bracing are really cob, but she has held together with them so far and providing those dozens of nails are not rusting out, should continue to do so. You are obviously used to the space lost to them, so your solution of adding ply gussets is a good one.
    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 Dody View Post
    After reading about Anchorfast/Gripfast nails in Monel or Silikon Bronze in the "Boatbuilding Manual", but also in "The Harbourmaster called me today" (love his shed, it's awesome!!!) the idea struck me that once I've got the plywood Epoxy-Filler-glued in place, I will never again be able to get to the nails holding the planks to the frames (or however we might call them). Using Monel or Silikon Bronze I would (hopefully) never ever have to touch them again.

    I looked a bit around, I could get Anchorfast nails in Silikon Bronze, the max standard size would be 4.0 mm x 75 mm = 8 Gauge x 3 ". Possibly they would be able to have different sizes made, but I haven't asked yet.

    First question:

    Would I have to pull all the old nails out if I wanted to use Anchorfast nails, or can they stay in? The old ones were galvi, and I don't know if this will cause a reaction. As far as I can see at the moment there would be space enough to just add the Anchorfast nails.

    Second question:

    I am getting a bit mixed up which size I would have to use. The local shipwright would have used galvi-nails, 90 mm long and (including the galvi) 3.9 mm thick which somehow looked right. The table on page 128 in my book ends with a plank-thickness of 1" (my - whatever we call them - are 30 mm thick which would be something like 1" plus 4.6 mm). In this book the nails should be 2" x .238" - which is much thicker but shorter.

    Third question:

    am I overlooking something?

    Thanks, Dody
    Pull a couple of the galvo nails to see if they have started to corrode, then seek advice on what you find. If the plank is dry and the galvo looks OK, you shold be OK with monel.
    The thick fat nails recommended by the books are I assume for conventional caulked carvel, where the nails do the work that in your boat is shared by the glued plywood skin, so a lighter nail may well work.

    Do not add the new nails between the old ones, that creates a line of perforations along the frame line, like the perforations between stamps. Drive the new nails for'd or aft of the old ones.
    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

    I think the frames were initially designed as web frames with that diagonal brace as a knee and the deck was to be flat. Then the curved deck beams were added with the triangular spacer and the original beams cut. The ply gussets you added will act as knees.

    You don't need no stinking nails to fasten the new ply. Use staples, after the epoxy cures it will be stronger then the wood. Removing the old nails is probably not really feasable. 40 000 clenched nails driven in larch 60 years ago would be a tall order. I would inspect the stringer to frame nails, oak likes to eat galvanized nails, and refasten there.

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

    Quote Originally Posted by Rumars View Post
    You don't need no stinking nails to fasten the new ply. Use staples, after the epoxy cures it will be stronger then the wood. Removing the old nails is probably not really feasable. 40 000 clenched nails driven in larch 60 years ago would be a tall order. I would inspect the stringer to frame nails, oak likes to eat galvanized nails, and refasten there.
    Rumars, I guess I didn't manage to express myself very well. My question was about the nails for the connection between frames and stringer or plank or however we are gonna call it. Exactly these old nails are the reason why I'll be pulling the whole fibreglass off the boat and with it the 4 mm ply because in places they were giving up on me and I have to bang new nails into the frame-plank-connection. This connection I would like to do with Monel (if I should manage to get it) or Silicon-Bronze. And this connection is, what I was asking about.

    On the other hand, the nails you are talking of now, the ones holding the ply in place, they pull out easily. Well, sometimes the whole nail, sometimes whatever comes out, because in many places they are fairly gone. In the aftcabin, where I started, whatever didn't come out with taking the ply off, I could easily pull out with pliers from the inside. Which I've already done in the whole aftcabin. Yes, sure, it's additional work and takes time. But why have some rusty stuff staying in the wood when it's only a tiny extra effort to get rid of it?
    Attaching the ply to the stringers (or planks, or however we like to call it) I will do with my new nailgun and the inox-nails. From the effort or time it doesn't make any difference if I use the pneumatic stapler or the pneumatic nailgun. But: there are some bends where I will just manage to get the plywood around as it should be. The staples haven't got enough strength to pull the ply close enough, the nails do.

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

    Sorry I misunderstod. Conventional wisdom is that screws are better than nails for plank to frame connections, but nails are certainly ok. How is the connection nailed now? One or two nails? If two how are they arranged? How thick are the frames? The article said 40mm but is that true? The frames look really deep so a longer nail is ok. Maybe a photo would be good so we can better understand.

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

    Quote Originally Posted by Peerie Maa View Post
    You are fortunate to have found a shipwright, it is what the boat needs.

    Those triangular bracing are really cob, but she has held together with them so far and providing those dozens of nails are not rusting out, should continue to do so. You are obviously used to the space lost to them, so your solution of adding ply gussets is a good one.
    You'll probably laugh when I say that I even gain a little bit of space with the plywood gussets . Sure, still far away from doing something about the interior, but to keep things moving from one cupboard to the next, plywood was added on both sides of wood. Probably it doesn't turn out very practical in the end, but at the moment I'm still hoping to find a way to give them a double-function in using them as a separator between cupboards as well.

    I am very happy too about the shipwright beeing here. Sure, his standards were always focused on fishing-boats and workboats, only the last 3 or 4 years he started helping out occasionally on wooden sailing boats on passage who were having a problem and I asked if he could help them. On the fishing-boats he's doing really amazing things, and often I have to stop watching what and how he is doing, it is really impressive to watch. He's using some old handtools, like a how for example, but also works with the chainsaw and lots of other stuff. Most of the time on his own, sometimes his 75 year old dad has to lend a hand and since this spring he's got an apprentice as the workload is just gettting too much. The amazing thing is that here in Portugal the paperwork and costs involved to register a brand new boat and get the licenses is so hideously expensive that it is much cheaper to re-build, even if everything has to be replaced, and this even for 25 m boats!
    Last edited by Dody; 07-12-2017 at 08:34 AM.

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

    Quote Originally Posted by Peerie Maa View Post
    Pull a couple of the galvo nails to see if they have started to corrode, then seek advice on what you find. If the plank is dry and the galvo looks OK, you shold be OK with monel.
    The thick fat nails recommended by the books are I assume for conventional caulked carvel, where the nails do the work that in your boat is shared by the glued plywood skin, so a lighter nail may well work.

    Do not add the new nails between the old ones, that creates a line of perforations along the frame line, like the perforations between stamps. Drive the new nails for'd or aft of the old ones.
    I haven't sourced Monel yet, so far I've only found Silikon Bronze. We did pull some nails of maybe 70 mm length out of the planks that where removed from the stern, but taking these pictures I realized that one of my problems is that some nails were far too short!!! Both of these planks will be replaced, have a close look at the nails:




    And thanks for the hint with with the perforation, done that a bit wrong already:


  30. #65
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    Default Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    Quote Originally Posted by Dody View Post

    And thanks for the hint with with the perforation, done that a bit wrong already:

    Well your only option there is to nail alongside, not in between those nails. The other holes make it look as though she was built out of second hand lumber.
    Explains why she is strip planked and sheathed.
    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 Rumars View Post
    Sorry I misunderstod. Conventional wisdom is that screws are better than nails for plank to frame connections, but nails are certainly ok. How is the connection nailed now? One or two nails? If two how are they arranged? How thick are the frames? The article said 40mm but is that true? The frames look really deep so a longer nail is ok. Maybe a photo would be good so we can better understand.
    Have you ever heard of Anchorfast or Gripfast nails? I never heard of them before but found them explained in the "Boatbuilding Manual". They describe them as "threaded nails", the wood-fiber is supposed to resist withdrawal. In this book it is said "... It is claimed that it takes 65 percent more force to pull this threaded nail than an unclinched galvanized boat nail, 31 percent more than a clinched boat nail, and 3 percent more than a woodscrew ..." As said before, I'm not a boatbuilder, I have never heard of these nails before, and have no experience it they are good or not. Trusting what is said in the book they are now used by many professional shipyards. The thing sounds quite clever to me, and it does make sense. This is why I am thinking of using them. But, maybe someone here in the Forum has firsthand experience and can say something about it?

    Framethickness, I measured 10 of them and they were all nearly 40 mm. He slightly planed them, so they end up between 38.9 mm and 39.8 mm wide. Concerning the depth the major part is 150 mm, going down in the inner bit of the corner to 50 mm (but that's the tip only). Hm, don't know how to explain this. Here is some pics:



    inside this corner is, where it comes down to 50 mm.

    Sorry for the chaos:




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

    Quote Originally Posted by Peerie Maa View Post
    Well your only option there is to nail alongside, not in between those nails. The other holes make it look as though she was built out of second hand lumber.
    Explains why she is strip planked and sheathed.
    The little holes are the ones from the nails I pulled out which were holding the old 4 mm plywood in place.

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

    Quote Originally Posted by Peerie Maa View Post
    Well your only option there is to nail alongside, not in between those nails. The other holes make it look as though she was built out of second hand lumber.
    Explains why she is strip planked and sheathed.
    If it was new lumber or not I can't say. For me it looks more like new lumber in these pictures:

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

    Quote Originally Posted by Dody View Post
    The little holes are the ones from the nails I pulled out which were holding the old 4 mm plywood in place.
    Ahh, that explains that puzzle.
    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 Dody View Post

    Framethickness, I measured 10 of them and they were all nearly 40 mm. He slightly planed them, so they end up between 38.9 mm and 39.8 mm wide. Concerning the depth the major part is 150 mm, going down in the inner bit of the corner to 50 mm (but that's the tip only). Hm, don't know how to explain this.
    A quick lesson in boat terminology. Planking has thickness.
    Frames (including the backbone framing) have two scantlings. Sideing is the dimension between the flat surfaces. The dimensions between the curved surfaces is the moulding.
    So your frame futtocks are sided 40mm, and moulded anything between 150 mm down to 50mm.

    When deciding on the fastenings holding the plank to the frame, the plank thickness is the critical dimension driving the nail size.
    It really is quite difficult to build an ugly wooden boat.

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