The Shipyard ( Dry Dock ): Builds & Questions > Yachts and Sail

Carina sailboat - my scratch build!

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Hellmut1956:
Dear friends


as promised or may better said as I have threatened to do, here the report of my eternal build from scratch of a sailboat with long keel based on the plan of the Voilier from a German source. The plan is the copy of a copy of a copy and as such distortions of it have made it necessary to do a lot of rework on the plan to be able to use it. I was quite disappointed when I got delivered the plan that did not consist of more than a DIN A0 sized paper.







This plan used to build the Carina is even in worse shape, as I did not care enough of it when I build the first hull using this plan the sail boat called the Sabrina. Then my son Andreas had to embarque into a school work in its 8th class and so he accepted my offer to build a hull based on this plan. For me the intention was to build a light version of the sail boat, as the first resulted too ambitious.





So the first step in this project for my son was to digitize the frames of the plan and the top and side views. For this he started with good old fashion technique using oil, to make the paper of the plan transparent and a needle and pass the shapes onto coordinate paper.





We used the Excel Chart feature, were the previously recorded digitized values were stored to fix the values that were evidently wrong. A nice side effect of this was, that errors while digitizing the data became evident and could be corrected.

Having done this we used the result to fix distorsions and to ensure the curves were smooth. Then we passes the frames into a CAD package you can get for free, called "Solid Edge 2G Drafting". Here an example:





You can see that we added "ears" to the frames. The reason for this is that we choose the the upside down method of building the hull and all frames had to be placed at such altitude above the base, that the design waterline had to on a horizontal plane parallel to the base.





We than printed the frame images and glued them onto a 4 mm thick wooden plate. I want to indicate, that heavy paper or even better, carton should be used, as normal 80 gr. paper tends to change its shape, when the glue is applied, as it gets wet. This wooden plate used is called "Siebdruckplatte" in German. This king of wooden plate is used to build concrete formwork. It has the advantage to have a surface that is very resistant to mechanical and chemical stress, here the advantage is that it is very brittle. You will see later why this is of huge benefit!





As you might see looking in detail into the foto, I used the zip-principle to glue the ridges onto the frames, 8 x 3 mm cross section.





To ensure the hull would not be distorted during the construction, we glued the ridges, one at each side, making sure the stress would stay symmetrical.





When I build my first hull I was worried about how easy or difficult the glueing of the ridges would be, specially at places like the one shown in the picture, were different shapes come together. But it proved to be no problem. The most difficult one was glueing the second ridge after the one following the deckline next to the stern mirror. The first ridge following the deckline had to be glued vertically, the second hat to follow the large change of the frame shape.





The reason I used pine wood for the ridges, was the grain of the wood. I want to highlight the old wisdom of anyone familiar with handcraft work, that any error that can be fixed early in the work process saves from having to spend 10x the effort to fix it later! So spending effort to get perfectly shaped frames is well spend to save work while grinding. my son had the great idea of taking some images from within the hull to make the construction visible. Next some pictures made from within the hull!





I love this picture as it shows the frames and the ridges glued to them. But also interesting has proven to be the fact that even the filigran shape of the frames was OK and it facilitates the pressing of the ridges onto the frames while glueing them.







Now a picture from the grinding phase of the construction of the hull.





While no doubt it is a tough job, it is also honouring it with the results! excuse me if you consider it not appropriate. But sliding the hand surface of such a wooden hull after some grinding gives a wonderful feeling, some consider as great as doing the same with a woman! Wood is a wonderful material to work with! To motivate myself grinding, I like to proceed, changing from grinding one side until it feels pretty good and than change sides. The result is, that the actual side being grinded at the end feels so much better, that you end up really wishing to improve the other side! Grinding of the hull took nearly 3 weeks!





When the grinding has reached a quality of the surface that seems fine, I like to apply G8 polyurethane varnish, with thinner, using 4 parts of thinner and one part of the varnish. One one side this varnish has the effect to protect the wood from humidity that might come in touch with it if the lamination gets damaged, but in this phase of grinding the hull it has the effect of improving the light reflection of the surface of the hull making irregularities visible.





Remember, I cannot use filler, as i want to keep the grain of the pine wood visible. On the picture you see me working on removing the hull from the base. The frame had been fixed to the bars screwed onto the base, but the glue falling onto it while glueing the ridges onto the frame, made it necessary to use a tool to remove the frames. You can also see how the G8 has changed the color of the ridges, while this is also a prove that the wood is well protected against humidity, as the thinner helps the G8 varnish to penetrate deep into the wood.





Here a picture of the base showing the principle of how I fixed the frames onto it. The planarity of the base is key, as any distortion would pass onto the hull shape being build. So I use the thickest wooden plate available and do reinforce it applying stabilizing wooden frame at the length on both sides.





Here a view from the toüp of the whole hull, just after removing it from the base. You can see, that the frame are already implementing the curvature of the deck, a useless effort, as the frames broke easily due to the brittle nature of the wood used! The weight of this 165 cm long hull was just about 450 gr, including the frames!





Here you can see how the frames got spoiled over time. But this apparently weakness proved to be marvelous! As the frames were so brittle, removing them, just using a tong, grasping a piece of the frame and turning the tong. This way the frames could be removed leaving nearly no trace on the hull!





Isn't this a great result? Such a clean inner side of the hull, that just required a bit of grinding, would make it much easier to laminate the hull from within. But it also reduced the weight. of course I did also apply a few layers of G8 varnish to the inner side to make sure the wood was well protected against humidity! But there are 2 more things I would like to highlight in this picture. One being the fact that I did fill up the front most and the rear most compartment made by the frame with epoxy. And that I did insert at this phase only in the front an aluminium piece in it where the screwed hole was prepared to connect the fixing point of the mast. This way that pont was firmly integrated into the hull structure. later same was done at the rear.


The second point I want to highlight is the lead I am casting into the bottom of the keel. The technique used and that prevents the wooden ridges to suffer from that process is as follows. Fist i just cast a bit into the hull and let it cool. The amount of heat energy of just a bit lead is not enough to endanger the wood. Then, as i add more lead, the already present lead works a a heat sink, absorbing the lead of the later one applied, so that on every step more and more lead can be casted into the hull without damaging the wood.


Here a more detailed view of this.





remember, that on a sail boat with long keel every effort has to be done to have the center of gravity as deep in the hull as possible. Just let me tell you, that the final displacement of the hull allows for a total weight of the sail boat of 29 kgs!





Here you see me laminating the hull with glas fiber and epoxy from within. it is important to mention, that as wood works, to prevent this from making the ridges noticeable when touching the hull from outside, symmetrical lamination from the inner and the external side of the hull is mandatory. i have used 29 grs per square meter weight glas fiber for the lamination, but up to about 100 grs is OK, and you would not see or feel the lamination when touching the hull!





Here the compensation for all those efforts! i sometimes think it would make sense to leave the hull like this, as the color is to my personal oüpinion marvelous! I want to stop here the report to reflect the achievement reached at this point and continue the report as a reply to this contribution!

Martin (Admin):

    :-))

rmaddock:
Fantastic work Hellmut!

Great to see somebody trying to be even more hi-tech than me!  I thought I was being clever using 3 Picaxe controlled winches  :o

I'm also fascinated to see that you've poured the lead directly into the hull.  How easy is that?  I've always struggled making plaster casts first and then sand moulds.  When I put the lead in my current project, a GRP hulled sailing trawler, I thought about pouring it straight in.  I'd read that you could - especially if you put the hull in water as a heat sink.  But every body said NOOOO!!!!!!!  If you can pour molten lead into wood then GRP should be able to withstand the same.  Next time I'll be brave enough to try.

Keep posting.  I, for one, am eager to watch your build.  I'm not going to comment on your thread about your workshop as it makes be feel ill when I compare it with my cellar  <*<

Cheers!

Robert.

Hellmut1956:
Well, allow me to repeat it. pouring molted lead into a wooden hull is no problem and the hull put into the water would be of no help anyhow, as the wood isolated the heat coming from the molted lead, as a consequence, not working as a heat sink! by proceeding as I described, pouring into the full first just a little bit of molted lead, this first lead inserted into the hull will work as heat sink for later added lead. Just keep in mind, it is a management of the heat energy that is in molted lead. You should never add more molted lead into a hull, as the already in the hull present lead can absorb as heat sink! It is in first degree, not so much an issue of the total quantity of lead within the hull, but of the lead surface onto which you pour additional lead. You want the molted lead to transfer its heat energy as fast as possible to cool down enough not to burn the wood!


As to the electronics! I started it simple. A friend of mine and I came together in my work shop, mounted a mega8 controller vom Atmel onto a board with through holes, an exercise of just on hour may be, connected a display and connected the slots of a receiver, the signal carrying line, to one of the pins of the controller. The ground and positive pole were used to supply the controller circuit with power, just 5 VDC. Than we used the BASCOM compiler, you get it here for free. After just 20 minutes we were able to display the length of the signal being offered to control i.e. a servo. Its called PWM as you well know, that repeats about every 20 ms. Just 10 minutes later we displayed the signal length of all 8 channels. having decoded this way the signals the control stick and switches settings from the transmitter were available to the software and could be used in any way. I can publish a tutorial about this, if there is an interest for this!


Now, a couple of years down the road, I do plan to use a board from NXP called LPCxpresso, here is one source that indicates the cost of this board is just 20.- Euros! This is so inexpensive that I plan to use many of those within my model, as this one comes with a sophisticated quadrature decoder as a built in peripheral, that I cannot just control an home made board with a brand new module from Trinamic, but i also can decode the position data from an magnetic angular encoder, that gives me more than 12 bits of angular position resolution. The wonderful issues with this board is that it comes with an JTAG IF on an extension of this very board, so that a debugger of the also free IDE can debug in real time in the target hardware. But also the IDE from Code Red, recently acquired by NXP, does know the lpcxpresso boards and builds the whole environment, so you do not need to setup the tool chain or the make process.


Additionally the ARM core of this controller, an ARM Codex M3, has, like all ARM Codex products in the market, the same application programming interface, short API, to use the peripheral modules on chip! So you do not need to worry to write the drivers for those peripherals. On top you get code samples for the use of all peripherals, which being reused just need to have the parameters adapted to your needs! So for somebody to start to dwell into the wealth of using own micro electronics circuits, starting i.e. with an Atmel mega 8 to open the boxes perceived as black boxes and the tutorial I mentioned, can start to combine those like lego stones to build its own function!


A later step is i.e. using the Arduino boards with the wealth of so called "shields, expansion boards to add functionality, i.e. 2.4 Ghz communication via XBee Pro, or al a later stage data communication via cellular phone data communication. I am waiting for a good 3D camera of the size of a USB stick, I am sure this will come by the time I need it, to be able to operate my sail boat by "First Person View", short FPV frm looking out of the head of the skipper on board!


Combined with this is the idea of building my own control remote around an Android Tablet, which would still have the control sticks and a reduced set of switches and rotating controls, as we know them from todays transmitters but assigning the function to them dynamically through the Android App that would implement the GUI, Graphical User Interface and the interface to the external hardware via an USB I/F. Such a unit would allow to connect FPV goggles to it and as we all know from using Skype, display the content of the video coming from the boat via the cellular phone video stream! i believe 2.4 GHZ in the midterm will die again, as the performance and real time abilities of the data com via cellular phones improves. For us, the builders and skippers of model ships, real time is much less critical as it is to the flying part of model building!

john44:


  But every body said NOOOO!!!!!!!  If you can pour molten lead into wood then GRP should be able to withstand the same.  Next time I'll be brave enough to try.




Do not use water as a heat sink, if the molten lead melts through the grp hull
you will get burnt from its explosive reaction to the water.
that is why everybody said NOOOO!!!!!
so please don,t be brave enough to try it.

john

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