Re-building my Ketch Tonga (1960)

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • Dody
    Tonga!
    • Jun 2017
    • 979

    Re-building my Ketch Tonga (1960)

    Hi together,

    I've found some amzing projects and very interesting information in your Forum, and am now one of your newbies !

    Maybe I better introduce us first: we, that's Tonga my composite ketch launched 1960, Mr. Max the cat (arrived here in winter 2015 and couldn't be convinced that life on a boat will be difficult for him) and me (Dody, 1962, ex office-worker but didn't do much practial stuff with my hands, female). Tonga and me have been sailing together since 1996 when in 2010 I discovered her plywood-deck needs replacing. I started, but sailed away with a mate for 3 months, but it turned out in the end that we've actually been away for 23 months. When I came back in 2013 I had to take my whole interior out as rainwater had got in (only kept my bunk). All the interior was covered in fungus and spak, but the hull was not affected. So, I really started with my deck. From bow to cockpit the new deck is installed now. When I ripped off the aft-deck I found - as kind of expected - that the previous owner and builder of Tonga had altered the form of the stern. Originally she was positive stern, he added a negative stern to it. Water was sitting in between the two not doing any good. So, together with the local shipwright for wooden fishing-boats we re-built her stern. During this operation we found out that after 57 years the nails connecting the planks to the frames are giving up, meaning I've got to bang new nails in each connection. On top of the planks was one layer of plywood in 4 mm, 14 cm wide and nailed on in a 45-degree angle, on top of that fibreglass and filler. Fortunately for me now, this was done with Polyester. Fortunately in so far as it never managed to get a good bond with the plywood and is fairly easy to take off.

    I've already ordered the plywood for the hull, had it cut in 14 cm strips (am using 6 mm ply as I tested and found out it bends easy enough in the closest bends), and I will go for 3 layers, one crossing the previous one. The layers of ply will be bonded together with Epoxy, and on top of that 3 or so layers of fibreglass, probably the exterior one in Carbon or Kevlar for more protection against little icy bits etc. So far so good.

    I would like to know your opinion about what you think would be the best way to do the connection with the planks (they have been heavily treated against all kind of ugly stuff in the building-process of Tonga, they are not painted or varnished, but they received from me several layers of linseed-oil mixed with wood-preserver), and the first layer of plywood.

    The guys where I get the epoxy from try to convince me to epoxy and filler-glue this first layer on, with staples till the epoxy has cured.

    For some reason I don't trust this bond to hold forever, although it might be pretty stiff. I've made some tests with one of the old planks and the new ply. With the hammer I managed to break the plywood, but not the bond. Still, I've ordered a pneumatic nailgun and 20.000 nails, in inox because, strange enough the inox-screws that were used during the building-process in several places under and above water are still perfectly alright.

    What scares me is the question how the planks will love it long-term. They will have no possibility to breathe on the side where they are glued to the plywood, which they can on all other 3 sides.

    Please let me know your ideas and thoughts about it!

    Fair winds and sunny greetings from Portugal
    Dody

    Sorry, I resized the photos 6 times now, but he still wouldn't take it, must be doing something wrong!
    https://www.facebook.com/photo.php?f...type=3&theater
    Last edited by Dody; 06-27-2017, 05:48 AM.
    fair winds, Dody
    "They did not know it was impossible so they did it" - Mark Twain
    www.tongabonds.com
  • Peerie Maa
    Old Grey Inquisitive One
    • Oct 2008
    • 62422

    #2
    Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

    Hi, and welcome to the forum.
    The FAQ page has got instructions for posting your pictures on here.









    I think that gluing on with epoxy is the right way to go, otherwise you will have a suspect carvel boat sitting inside a weak cold moulded boat. You could ask the epocy manufacturer about removing some of the oil from the surface, and if it is necessary.
    The owners of the Falmouth Quay Punt Curlew laid a new diagonal skin over her, using techniques similar to your proposal. http://forum.woodenboat.com/showthre...ay-over-carvel
    It really is quite difficult to build an ugly wooden boat.

    The power of the web: Anyone can post anything on the web
    The weakness of the web: Anyone can post anything on the web.

    Comment

    • wizbang 13
      Senior Member
      • Oct 2009
      • 24799

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

      I would not put "plywood" over the goofy planking,but rather mill actual lumber into thin strips, and continue to cold mold her.In other words, make your own plywood as you proceed.
      It is a screwy lookin construction, but as she is almost 60 years old....
      I recon you are looking at an easy 50 gallons of epoxy.

      welcome to the forum
      bruce

      Comment

      • Rumars
        Senior Member
        • Dec 2016
        • 1316

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

        It's a big job you have there. Cold molding over carvel or sheating is often done. Search the forum for it.

        From the look of the planking I suspect the boat was intended from the start to be sheated and constructed that way. Stop asking yourself how the planks will do. Up until now they also could not "breathe" on one side and the boat was fine until the deck let go. Just keep the deck leck free and it will be ok. Neglect the deck and you will have the same problems you have now. Glass the deck and please glass the hull deck joint aditionally.
        Plywood sheating is not ideal, wood veneer would be better, but ply also does the job.

        Do you know what wood was used initially for planking and structure? And what are you using now for the repairs?

        In order to assure a good bonding you have to have sound, clean and dry planking. So first thing to do is completley remove the existing sheating and plywood. The big rub/toerail also needs to go. Then you have to replace every single rotten piece of wood in the boat, and refasten where needed. Then you sand the whole hull agressively until you have clean wood. Tell the workers to stop using red lead between the planks and stop soaking the planking with anything. You will need to clean all the seams. Depending on how open they are you then either use epoxy putty to fill them, or spline with thin battens. Another sanding to get everything fair and after degreasing with acetone you are ready to glue the ply on. Since this is a big job done outside and all the ply has to be spiled I would first spile all the ply strips (hold them in place with some temporary screws or staples) number them (permanent marker please not pencil) and glue them on all at once. This would also give the hull more time to dry out in the sun. So you first clean the seams, then sand the hull, then spile all the strips, then remove strips, fill seams, glue the ply on.

        I would only use two layers of ply at 45°, the third is not necessary. The hull has carveel scantlings already and was fine with only one layer of 4mm ply so two layers of 6mm is more then it needs. After all this the glass on top is only for abrasion. How much glass you want to put on is up to you. One layer of 200g/sqm with some reinforcements along the stem and keelline would be enough but you can go as high as you like. For "icy bits" you also need reinforcement along the waterline. Just keep in mind that putting a lot of glass on the topsides is just dead weight and aded expense. Carbon is not necesarry it will do nothing for you. Kevlar has good abrasion resistance but is difficult to use. If you feel you need more protection just use more glass.

        Download the Gougeon Brothers on Boat Construction and read it.

        Ask around if there is someone who can sandblast with soda (sodium bicabonate) that would be the fastest way to clean the hull inside. But please only soda not sand or corund you only want to clean the wood of paint not destroy it. And don't do it if the operator has no experiece with blasting wood.

        Comment

        • Dody
          Tonga!
          • Jun 2017
          • 979

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

          Thank you alll, this is super-helpful just a quick reply as have to get on before it gets too hot: the wood originally used was oak for the frames and larch for the planking. The frames are ok, I can see all the planks in the hull from the inside and one or two need replacing in the process. I can't get larch, for the stern we used Gamballa, and for the parts where the Gamballa was too rigid the only wood we could get was scotch fir. As scotch fir is not very rot-resistant I treated them with red-led (there are no workers apart from Albertino the local shipwright with whom I am doing the planking, so the bang with the hammer for using this is for me). Is it really necessary to epoxy-putty or spline with thin battens? I was hoping to get away without doing this as she didn't have that before?
          I've read the Gougeon Brothers and also Buehler's Backyard Boatbuilding. Have ordered 2 more Boatbuilding-Books which should arrive today or on Monday, one by Howard Irwing Chapelle, the other by Robert M Steward and Carl Cramer as there is heaps of other questions I've got and havent found the right way yet.
          fair winds, Dody
          "They did not know it was impossible so they did it" - Mark Twain
          www.tongabonds.com

          Comment

          • Rumars
            Senior Member
            • Dec 2016
            • 1316

            #6
            Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

            If you don't close the planking seams the moment you begin stapling the ply on, all the thickend epoxy will go into the seams and you will be left with a starved joint at best. It will be like pressing dough trough a sieve.
            I don't know how the original ply layer was fastend, but I suspect nails or screws not adhesive. Epoxy is stronger than nails. Plastic staples can be left in place and sanded.

            Gamballa would be Iroko (Kambala)?

            Comment

            • MN Dave
              Banned
              • Jul 2011
              • 3120

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

              I would like to know your opinion about what you think would be the best way to do the connection with the planks (they have been heavily treated against all kind of ugly stuff in the building-process of Tonga, they are not painted or varnished, but they received from me several layers of linseed-oil mixed with wood-preserver), and the first layer of plywood.

              The guys where I get the epoxy from try to convince me to epoxy and filler-glue this first layer on, with staples till the epoxy has cured.

              For some reason I don't trust this bond to hold forever, although it might be pretty stiff.For some reason I don't trust this bond to hold forever, although it might be pretty stiff. I've made some tests with one of the old planks and the new ply. With the hammer I managed to break the plywood, but not the bond.
              Have you tried this test on a board treated with the linseed oil and preservative the same way you treated the new planks?

              There was a thread here in the last year about a boat builder who deliberately planks his boats like carvel but with gaps a few mm wide and then caulks them with thickened epoxy. Even if the bond between the treated wood and plywood sheathing is weak, the thickened epoxy forced into the gaps and the staples will provide considerable shear strength. I don't see a problem with starved glue joints, but swelling of the planks with a rigid material between them can generate a lot of pressure. I think that you will need to coat the inside of the planks to keep them as dry as possible. I don't know the solution, but I see a potential problem. An alternative would be to add a layer of cloth between the planks and the sheathing to prevent the epoxy from filling the gaps. Hopefully someone with more insight in this area will correct me or provide better information.

              Red lead comment: The red lead is not a good preservative. Red lead does keep the paint more flexible and reduces cracking of the paint, so it is still a good protective coating. Personally, I don't like creating so much hazardous waste, but until the boat is scrapped, the paint works well enough.

              Edit : Related thread http://forum.woodenboat.com/showthre...ay-over-carvel
              Last edited by MN Dave; 06-23-2017, 10:52 AM.

              Comment

              • Phil Y
                Banned
                • Apr 2010
                • 21066

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

                That's a big project, good luck with it. Seems to me that doing it the same way it was done before is a pretty reasonable approach. I'd worry that linseed oil on the planks might compromise the bond with epoxy though. As someone commented above, you will want to get the planking as clean and dry as possible, and rough them up plenty too.

                Comment

                • Dody
                  Tonga!
                  • Jun 2017
                  • 979

                  #9
                  Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

                  Thanks Nick for posting the photo, and thanks to you all of course and thanks for the links!

                  Where do I start? Best with the wood. In the shop it was marked "Kambala Escura", on the bill it says "Zazange" which is 2 different names for the same thing. I tried to find out something on internet. The english name is "West African Albizia" which hardly gave me any information, the French name is "Iatandza" and there some info popped up. It comes from Africa, seems pretty similar to Iroko from the looks, smell, and qualities but is a bit less difficult to work with - although tools do get blunt faster than with other woods.

                  Linseed oil. I only know about it since I'm in Portugal (although it is used on ships for hundreds of years). Every 3 - 4 years most of the local fishermen strip their paint completely off the boats, apply one coat of linseed-oil, let it soak in for a few days and then start with a fresh paint job. So far I found out it's anticorrosive, strenghtens the wood and makes it more water-resistant. It doesn't affect the breathability and is part of the better range of oil-based paints. I applied it together with wood-preserver on the inside of the hull the moment I had my interior out. Mainly because I was too scared fungus or anything else might have had ideas to find a new home in my planks, but also to give them a bit of a treat after 50 something years and increase their resistance against water.
                  My whole boat got 3 coats of linseed-oil 50:50 with wood-preserver from the inside in 2014, the aftcabin an additional coat in January 2017.

                  The plank I used for the test was one we had to shorten to install the new planks while re-building the stern. Which means it was old, came from the aftcabin, and her last linseed-oil was applied in January 2017. To make the test more interesting and find out how it affects the bonding I used the treated side (inside of the plank) for glueing the plywood on. Thickness of the plank 30 mm, thickness of the ply 6 mm.

                  Test. I tried out 7 scenarios
                  1 - no sanding, no cleaning, held in place by a screw till the epoxy cured
                  2 - no cleaning but sanding, held in place by a screw till the epoxy cured
                  3 - sanding, cleaning, held with 2 staples
                  4 - sanding, cleaning, held with 2 nails
                  5 - sanding, cleaning, held with 2 screws
                  6 - sanding, cleaning, held in place by a screw till the epoxy cured
                  7 - sanding & cleaning as before, Epoxy on both faces but NO filler, held in place by a screw till the epoxy cured

                  After waiting for 7 days I tightened the plank in the bench, got my biggest hammer out (maybe 4 KG?) and started with all my available force on No. 7, the weakest of them all. A huge surprise for me happened: this weak bond without filler held, the ply broke! The next weakest should be the one where I didn't sand and didn't clean, No. 1. The same thing happened: the bond was perfectly alright but the ply broke. This makes me believe that big impacts don't affect the bond. Today I tried with flexing the ply to see what happens, but, as the ply only sticks out about 8 cm on each side I wasn't successful in breaking anything. I'll do some tests with a chisel tomorrow (just sharpened them all today) to see if and how I can destroy the bond. Will let you know what happens :-D!

                  Acetone. When reading the book of the Gougeon Brothers a huge surprise happened: nowhere in this book they mentioned Acetone. Whenever they were talking about cleaning, they were using Alcohol!!! Buying heaps of Vodka for the purpose was probably not what they had in mind I guess :-D. I asked around and what I found here is something called "blue alcohol", which is 90 % strong industrial alcohol with something else in it, and darkish blue so nobody drinks it by accident. I tried this stuff cleaning my epoxy-mess from the tools and it actually worked much better than Acetone. I also used this stuff for tests 2 to 7. Friends of mine then gave it a try with Epoxy-paint and 2-pack Polyurethane paint and were quite happy how much better it works. I've got no idea if it's less harmful than Acetone, but at least it doesn't dry the skin as bad as Acetone if you forgot the gloves for a moment.

                  Epoxy. I've tried a lot of stuff over the years. Although I'm always very particlular about getting the mixture right, the only one I never had a problem with was WEST SYSTEM. I absolutely hate doing things twice or clean up another nice mess. Imagine on a job like this being unlucky with a wrong batch of epoxy ... well, I'm not gonna try something else. I will end up with more than 200 KG of Epoxy-resin. Fortunately my supplier is giving me his yard-discount. I could save quite some more if I would next buy a 200 KG drum instead of sticking with the 30 KG containers, but I haven't figured out a cheap way of filling the resin into the 30 KG containers which I can easily carry around my workplace, the drum would stay in my workshop about 100 m away from my boat (was lucky to be able to rent one of the fishermen's workshops here in the port).

                  Planks and distance between planks. The planks have a thickness of 30 mm, the original 4 mm ply was nailed onto the planks without any glue or bedding-compound in between. Somewhere in the forecabin there is 2 planks where I've got a distance of 3 cm, with the rest of the hull it's between 0,5 and 2 cm. Albertino (the local shipwright) did a neat job with the planks at the stern, but the original planking is not that neat.

                  You are absolutely right, I should take the whole fibreglass off now to profit from the summerwinds drying it all out nicely. And yes, the toerail is coming off and the fibreglass of the hull and the deck will be joined together so no water can come in (there is another nice little mess waiting for me concerning keel and keelbolts ...). Trouble is, I've only got my 2 hands and last winter turned out pretty nasty sleeping in a boat where the complete stern was missing, the temperatures dropping below zero and the wind blowing fresh.
                  Right now I've still got plenty of work to do with the deck. The tiny little elevation on the aftdeck didn't have a carlin which I've started to make yesterday. When both of them and the knees are in I would like to close the transom first, so I can completely lay the rest of the deck from the cockpit to the transom (1st layer is 12 mm, screwed to the deckbeams with bedding compound, consecutive 3 layers 6 mm ply glued on with epoxy and epoxy-filler). I would then like to fibreglass the whole deck with filler or primer on top to protect everything from UV and water (right now the finished part has one coat of epoxy with peel-off cloth). When this is done I can remove my tent and get the toe-rail off (the hoops of the tent are fixed to the stanchions, which are screwed into the toe-rail). With the growing experience I'm getting much faster now, but still, somehow, everything seems to take ages and I can't have stress any more. I recon by the time I'm done with all this there will be just enough time to close the open stern-area with the first layer of ply so the wind and cold stay out and winter will be there (the rains start something around November normally). Winterjobs will be my new rudder, the whole construction aft where the rudderstock sits in etc.
                  Last edited by Dody; 06-24-2017, 02:10 PM.
                  fair winds, Dody
                  "They did not know it was impossible so they did it" - Mark Twain
                  www.tongabonds.com

                  Comment

                  • Dody
                    Tonga!
                    • Jun 2017
                    • 979

                    #10
                    Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

                    Originally posted by MN Dave
                    There was a thread here in the last year about a boat builder who deliberately planks his boats like carvel but with gaps a few mm wide and then caulks them with thickened epoxy. Even if the bond between the treated wood and plywood sheathing is weak, the thickened epoxy forced into the gaps and the staples will provide considerable shear strength. I don't see a problem with starved glue joints, but swelling of the planks with a rigid material between them can generate a lot of pressure. I think that you will need to coat the inside of the planks to keep them as dry as possible. I don't know the solution, but I see a potential problem. An alternative would be to add a layer of cloth between the planks and the sheathing to prevent the epoxy from filling the gaps. Hopefully someone with more insight in this area will correct me or provide better information.

                    Red lead comment: The red lead is not a good preservative. Red lead does keep the paint more flexible and reduces cracking of the paint, so it is still a good protective coating. Personally, I don't like creating so much hazardous waste, but until the boat is scrapped, the paint works well enough.

                    Edit : Related thread http://forum.woodenboat.com/showthre...ay-over-carvel
                    In this Gougeon Brother's book I found one construction that had many stringers with a distance of maybe 30 cm between them going all along the hull (and no planking). The plywood would be glued on the stringers and when explaining how and what they said to just scrape off the excess filler from the inside. I haven't got a clue but was wondering if I maybe could apply this technique on my boat?

                    I agree with you, something needs to be done from the inside to prevent water soaking into the wood. Trouble is I also keep reading again and again that the wood needs to be able to breathe so water that does get in has a chance to get out again. Tonga used to be fairly dry, but there is no way to completely keep water out and be it only that you come inside with wet rainies, a hose or a fitting breaks, a hatch accidentally left open when a shower goes down and and and.

                    Red lead, I wish there was something less poisonous on the market but it hasn't happened yet.
                    Last edited by Dody; 06-24-2017, 02:17 PM.
                    fair winds, Dody
                    "They did not know it was impossible so they did it" - Mark Twain
                    www.tongabonds.com

                    Comment

                    • Rumars
                      Senior Member
                      • Dec 2016
                      • 1316

                      #11
                      Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

                      Never heard of that african wood, but if similar to Iroko it's ok. Pine for the planking is a classic, no problems there.

                      Using epoxy from a drum requires either the use of a pump or you put the barrel on the side and use a tap. There are manual and electric transfer pumps and also taps that screw on standard 200L steel drums. Available at any better industrial supply shop. Just ask the diesel guy in the harbour where he got his, he uses it to transfer motor oil from the drums to the canisters. You need two of them one for the resin and one for the hardener, and never mix them up.

                      Why are you using first a layer of 12mm ply and then 3 layers of 6mm for the deck? Just use two layers of 12mm and one of 6mm. I suppose 18mm plywood will not conform to the deck chamber? Doing more layers then strictly necessary is just a waste of epoxy and time. After glassing paint it well and use nonslip.

                      How big is the boat?

                      Looking at the pictures I'm guessing that if the planking is 30mm thick then most planks are 50-60mm wide. And reading about the gaps I am pretty certain your boat was designed and constructed this way from the begining. The builder saved time (and money) by combining several building methods known to him. Or someone got creative and fitted out a plug intended to create a fiberglass mold and knowing that used good materials for building it from the begining. However it was he used narrow planking without spiling like in strip planking, nailed plywood over it to create a seamless surface and glassed it to be watertight, You are now converting the boat to a more orthodox building style, namely strip planking followed by cold molding. You need to close or open the gaps to about 1-2mm then fill them with thickend epoxy. You can make your own mixture or use Resoltech 2040G it's your call. It's not hard to do, I'll link some videos. If the planks are indeed only 50mm wide you could maybe just glass over instead of cold molding with plywood.
                      The inside is a philosophical question. Some are of the opinion that once you use epoxy you should encapsulate, meaning you sand all of the paint away to bare wood and paint three coats of epoxy on followed by paint or varnish. Others say it's okay without encapsulation just paint it well inside. It's for you to study and decide.

                      The construction method from the Gougeons book is ply or coldmolding over stringers. It results in a stiff and light hull. Converting your boat to it would require recalculating the structure.

                      Comment

                      • Phil Y
                        Banned
                        • Apr 2010
                        • 21066

                        #12
                        Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

                        Interesting construction. I wonder if epoxy is a mistake then? Those planks are going to move with changes in moisture, and their movement is much more powerful than your hammer. If you do go epoxy, I agree with others, you need to spline those gaps between the planks down to nothing. Of course I've never done anything like this, I'm just an arm chair quarterback here.

                        Comment

                        • MN Dave
                          Banned
                          • Jul 2011
                          • 3120

                          #13
                          Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

                          I found the threads I was thinking of.
                          <font color="white">&amp;nbsp &amp;nbsp &amp;nbsp &amp;nbsp &amp;nbsp &amp;nbsp </font> <h3>And, you can click <a href="http://forum.woodenboat.com/forumdisplay.php?12-Archived-Reference-Threads">Archived Reference Threads</a></h3>

                          <font color="white">&amp;nbsp &amp;nbsp &amp;nbsp &amp;nbsp &amp;nbsp &amp;nbsp </font> <h3>And, you can click <a href="http://forum.woodenboat.com/forumdisplay.php?12-Archived-Reference-Threads">Archived Reference Threads</a></h3>

                          It looks like he glasses the interior to seal the water out of the wood, which could be very difficult in this case. You can PM Mark Bowdidge about sealing the interior since he obviously knows a lot more than I do about this.

                          I used Google to translate "Kambala Escura" from Portuguese to English and got dark kambala, which comes up more readily on google. It is same as Iroko.

                          Kambala – a wooden chamaeleon
                          "This exotic wood, which is known in the countries of its origin under such names as iroko, abang, odum, intule, rokko and moreira, comes from the hot African continent."

                          See also http://www.wood-database.com/iroko/
                          Last edited by MN Dave; 06-24-2017, 06:07 PM. Reason: corrected link

                          Comment

                          • Rumars
                            Senior Member
                            • Dec 2016
                            • 1316

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

                            In theory one could repair as initially done and save a boatload of epoxy. In practice when this boat was constructed ocoume ply was regarded as barely good enough for packing crates, and marine ply was made out of rot resistant species. So now it's either epoxy or a complete replank in a traditional manner. Galvanized fasteners into oak frames have a defined lifespan so this would have been a expected outcome and the original boatbuilder probably didn't expect the boat to last 57 years without a complete overhaul, so we can say this is one lucky boat.
                            Do we know were the boat was constructed?

                            The Kambala escura is Albizia ferruginea not related to Iroko wich is Milicia excelsa. Seems to be a good wood for boatbuilding.

                            Comment

                            • MN Dave
                              Banned
                              • Jul 2011
                              • 3120

                              #15
                              Re: Wood - Plywood - Epoxy bond, re-building my ketch Tonga

                              After rereading the OP
                              On top of the planks was one layer of plywood in 4 mm, 14 cm wide and nailed on in a 45-degree angle, on top of that fibreglass and filler.
                              One layer of plywood, held only with nails and it lasted 57 years? It may be best to allow the planking under the plywood sheathing to work as it shrinks and swells by not attempting to bond rigidly. Perhaps a softer material like Sikaflex or 3M 4000 or 3M 4200 is better than a stiffer material like epoxy.

                              More information of no practical value to the OP:
                              Common names are always problematic. Kambala can be either iroko or albizia, but I think that the name is more commonly applied to iroko. The wood of both albizia and iroko is similar. Even the end grain looks similar. Albizzia has a bright green fluorescence under UV light. Iroko tends to dull tools.





                              Woody Species Milicia regia
                              Common name(s): Most known as Iroko Angola: Moreira Benin: Lokotin Cameroon: Abang Dem. Republic of Congo: Kambala, Lusanga, Mokongo, Moloundou Equatorial Guinea: Abang Gabon: Abang, Mandji Ghana: Odoum Guinea: Simme Liberia: Semli Mozambique: Mufula, Tule Nigeria: Rokko Sierra Leone: Semli Belgium: Kambala

                              Plant Resources of Tropical Africa Can't copy from google books.
                              Last edited by MN Dave; 06-25-2017, 12:55 AM.

                              Comment

                              Working...