Starting my Quattro 16 from Woods design

Discussion in 'Multihulls' started by pdw, Mar 19, 2009.

  1. pdw
    Joined: Jun 2008
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    Location: Mexico

    pdw Junior Member

    Dear all,
    I decide it, I start the construction of my Quattro 16. I will face some difficulties, the first one is that I´m not leaving in my own country (I'm in Mexico in a small island called "Ciudad del Carmen"), so I don´t have all the contacts, shops and so on to find all the supplies, and also friends with experience who can help me. Second, I will need to import a lots of things from USA, and that take long.
    After studying all the information provide by Woods, my first question is:
    :?: What is COLLODIAL SILICA? How do you use it? What is his purpose? I couldn't find in the plan where to use it, but it appear in the material list.
    I will, of course, give you the advance of the project via this Forum and post photos.
    Thanks in advance for any help provided.

  2. rayaldridge
    Joined: Jun 2006
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    rayaldridge Senior Member

    Colloidal silica is mixed with epoxy to thicken it for gluing or for forming fillets. I've successfully used 600 mesh silica from a pottery supply company-- much cheaper, and seems to work well enough.
  3. catsketcher
    Joined: Mar 2006
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    catsketcher Senior Member

    Cotton flock too


    You need two types of additive for your build. One will be high strength and medium density - silica - I use one called Cabosil. It is for turning clear epoxy into a glue. It is good for high strength fillets and gluing.

    The other additive is microballoons. This is low strength lightweight filler for fairing - smoothing out the hul or deck.


    Phil Thompson
  4. Manie B
    Joined: Sep 2006
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    Manie B Senior Member

    Hi guys,
    i do the same - nice to know that we even use the same terminology

    what i also do for strong fillets, is mix equal parts of cotton fibre for strenght and cabosil as a viscosity agent to thicken the paste
  5. rzj7l2
    Joined: May 2008
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    rzj7l2 Junior Member

    I also use glas fibres instead of cotton for (even stronger?) fillets. But no fun to sand down...
  6. Saylaman
    Joined: Dec 2007
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    Saylaman Junior Member

    Congratulations Patrick, I hope the build is very rewarding and the sailing even more rewarding. Please keep us posted as you progress.

  7. ThomD
    Joined: Mar 2009
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    ThomD Senior Member

    Most fillets don't need extra strength if they are on inside boxed corners. If one thinks there is a chance that the joint will flex a lot then I use cloth over the wet fillet.

    The various glass and cotton fibers give poor volume for a given amount of epoxy, same is true with the nice to use woodflour. That means more cost and weight in your boat.

    I use at least three components at various times:

    - A medium balloon like phenolic or Q-cell, mixed 3-4 parts Q to one part cab. I mix as much of this as I can into the epoxy without drying it out. Do overmix it at times so you really know how much you can add, because it is a lot. I use only as much cab in this mix as is required to keep the fillets from slumping, less cab means more yield and liighter weight. This can vary depending on what you are applying it to, and the weather.

    - I use cab alone for certain gluing jobs.

    - I use microlite for fairing. The only thing that compares to microlight in sanding ease and feathering out is talc which is too heavy. At least that I have tried.

  8. bruceb
    Joined: Nov 2008
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    bruceb Senior Member

    Patrick, Look on the site in florida, they have good info on the various fillers.
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