1:25 wally tango build log (in progress)

This project aims to create a 1:25 Wally 100 Tango model: LOA=1219mm, beam=288mm

Covid crisis and minimal ressources: a 28″ screen, openSCAD, some paper, two block of styrofoam, 3mm plywood… and a lot of “week-end” time.

Choices made:

  • composite hull because we are in the 21th century … and to keep the weight low
  • fiberglass Vs carbon to be more easily repairable
  • one hull is needed, I go for the lost (not really) mold method – The plug is used to build the final part directly. It is lower cost, faster and avoid me to store the mold after… the time saved on sanding/finetuning the plug will be use on the final part
  • full scale sail plan
    2020, April 4-12: my openscad design: Hull / waterlines
    24-Deg angle: waterlines look correct. Single rudder ok, still immersed, everything seems ok.
    45-Deg angle: waterlines look. hum… I have a doubt about the single rudder here.
    We will see;-) I am planning to make it larger than a real scaled one.
    And heeled now, buttock lines.

    Run with openscad.

    The first parameter allows to choose the display mode.

    i.e: processing=4 is generating one bulkhead, identified by the other parameter BH_id (range 0 .. 11). The bulkheads are separated by n*XPS_thickness (n is defined in BH_xpsnb array). This is the mechanism which allowed me to copy the bulkheads and prepare the styrofoam sandwich.

    You can also generate the STL files, print them, lasercut them, ..

    2020, April 18-19: Covid-19 == no 3d printer here. Old school but efficient method.
    Calibrate the screen size and copy over each bulkhead with paper.
    Mirror the imprint on the plywood and cut with a manual scroll saw.
    2020, April 25-26:
    40mm styrofoam cuts to reach the 120mm spacing stated between bulkheads.
    3 blocks of styrofoam and one bulkhead glued together and fixed on the support.
    (The bow has a lower number of styrofoam layers (two and one on the last bulkhead)
    reduced result before heavy hand sanding
    After sanding

    2020, May 2-3:
    Nothing much to do, still waiting for the delivery of fiberglass cloth. packing tape and mold release wax applied.

    2020, May 6:
    Hull lost mold fiberglassing.

    • 2 layers of 160gr/m2 sergé fiberglass cloth
    • Slow epoxy resin
    • Epoxy black RAL 9005 pigments
    The second layer of fiberglass is set at a 45 degrees angle from the first.
    The color is useful during fiberglass impregnation, it helps to make it even. It creates also a base for the hull final color, perhaps allowing less paint job.

    2020, May 9:
    lot of sanding (reducing a bit the previous fiberglass layers), epoxy putty to level properly the surface, sanding, the structural finishing double 160gr/m2 fiberglass layers, ultra light sanding, epoxy putty and final sanding!

    2020, May 10:
    Here’s come my 1200mm wally tango hull ! 😎
    Resin/Pigment/Putty/fiberglass total cost: ~50 Euros.
    Weight of the untrimmed hull: 720gr.
    I still have to trim a big part to the deck limit. I will probably land around ~600/650gr which is not bad at all considering it is a 1200m stiff hull with at least 2 layers of 160gr fiberglass. It should be able to take some rough hits.

    Trimmed! 610gr

    Borders: Light bulkheads with 3mm plywood and border are shaped with 3mm balsa. It aims to provide a light structure easy to finetune. I will see if an added G4 primer will provide enough strength or I will simply fiberglass the wood…

    3mm Balsa custom insertion

    Trimming and sanding

    Second layer of 3mm balsa on top and bevel

    Rudder and fin

    The rudder is 4 layers of 160gr/m2 fiberglass encapsulated between plywood and shaped. The middle fiberglass is for stiffness and leading/trailing edge hardness. 19cm, 30gr

    The fin is from center: 4 layers of 160gr/m2 fiberglass, balsa 3mm, 2 layers of 160gr/m2 fiberglass covering and fixing the middle shaped carbon tube of 8mm. The middle fiberglass is a bit for stiffness and mainly for leading/trailing edge hardness. The carbon tube has two purposes: stiffness and holding top/down brass knurl nuts.
    40cm, 7.5mm thickness, 87gr, bending 17mm with 1600gr bulb.

    Keel box is built on the fin: unidirectional carbon 200gr and multiple layers of fiberglass.

    Keel box settled in the hull, rock solid and light weight: epoxy glue against the hull, high strength unidirectional carbon 200gr stratified web over the box head and bulkheads, one layer of fiberglass 160gr over the seal (box / hull). I used black pigment in my resin to ensure visual control of the epoxy resin covering, it looks a bit messy but still very useful.

    The front is prepared and reinforced to hold the jib stay and possibly a classic headsail like the real 1:1 tango… but I will probably finish with a classic RC jib boom.


5 thoughts on “1:25 wally tango build log (in progress)

  • Hi there, awesome model! Looking forward to seeing how this progresses.
    I am thinking of building a tango modell myself. But I am not a CAD expert.. would you provide the cad file for private use?

    Kind regards

    • Hi, the hull is still progressing, but really slowly. The gliders took my spare time during the summer.
      I updated this post with the OpenScad source – based on an enhanced version of my module of “3d carving” available on thingiverse.
      Let me know if you start its twin !

  • Hi, awesome. Thanks a lot! Unfortunately it doesn’t seem to be the correct file?! If you could check that would be great.

    I will let you know how the twin goes. Will try to modify the model so it works for 3d printing.
    Looking forward to seeing your progress.


    • Hi,
      It is the correct file. Unzip it.
      Take openSCAD (opensource: https://www.openscad.org/downloads.html).
      Open the file “wally-tango.scad” with openSCAD.
      It is a fully parametric design. You can edit the .scad file with your notepad or text editor.
      The documentation is inside.
      For example, change the value of variable ‘processing’ to ‘2’. You get the full rounded empty hull.
      At any time, you can generate the STL file for 3d printing with OpenSCAD (F6 for rendering and menu: File>Export>STL)

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