a slick way to fair a deck on a 65 foot ferro cement sailboat

Discussion in 'Materials' started by awab, Jan 13, 2013.

  1. awab
    Joined: Jan 2013
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    Location: North Carolina

    awab Junior Member

    dear reader

    first some pics


    This is a boat I am working on now for 2 month and just stripped with a torch the paint and non scitt from the deck. After some sanding I will have a good base of healthy ferro cement. Now I have to fair out the deck before painting.

    I just came along a good system so far I understand and would like to have your opinion on what kind of compound I should use. I am looking for a compound which sticks to cement and can be thick some millimeters to one centimeter.

    Here is the system I would use if nothing better comes up.

    A slick way to fair a large area and avoid a lot of tedious sanding is to use a serrated trowel like the metal one floor tilers use to spread mastic. Apply the fairing putty using this tool leaving a series of parallel ridges that stand proud of the surface. Allow the putty to cure, and then sand the area with a long board. Notice that all you are sanding is the tops of the ridges, about one fourth of the total surface area being faired. Sanding dust falls into the valleys. Once the ridge tops are fair, the area is cleaned of sanding dust and the valleys are filled with fairing compound using a broad knife with a straight edge. Only a light sanding is then required for final fairing following cure. Seal with epoxy before painting.

    thanks for your interest.
    1 person likes this.
  2. robwilk37
    Joined: Nov 2010
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    Location: san diego

    robwilk37 Senior Member

    ive done the notched trowel thing and it works well. i had to give up on mixing my own bog though...no matter how well i measured epoxy/balloons/cabosil the density of the cured resin was slightly different, enough to telegraph the first peaks through the primer. now when im filling more than just a skim, i use allfair or some other pre-mixed fairing compound and the notched trowel.
  3. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    This is an old trick and one used on badly unfair surfaces. It applies an ungodly amount of filler, which is heavy and costly. Essentially, you are applying a raised surface, which is then faired. Yes, the process works quickly (relatively), but it has it's disadvantages too.
  4. JSL
    Joined: Nov 2012
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    Location: Delta BC

    JSL Senior Member

    Make sure the cement is sealed first or the osmotic pressure will blow the fairing compound off. Membrane sealers (epoxy)may work but better to use a penetrating/expanding sealer (Xypex) first and then the membrane.

  5. awab
    Joined: Jan 2013
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    Location: North Carolina

    awab Junior Member

    after seeing that awl fair or other ready mix compounds are 100.- and more for a gallon,
    I see it would cost a fortune to make this work with this kind of materials and this method.
    I been thinking having a ferro cement boat there should be cheaper materials out there to make a fair surface happening. Have to find something what sticks to concrete and easy to sand. Otherwise I still can only sand with heavy paper and use the rough surface as non skit.
    There is one product from xypex "xypex restora-top 50 " I found witch could be interesting.
    Product Description
    Xypex Restora-Top products are designed specifically for the repair and rehabilitation of horizontal concrete surfaces such as warehouse floors, bridge decks, roads, curbs, and walkways where the repaired area must be returned to normal service within two hours of the completed repair. Restora-Top products consist of specially modified Portland cement, aggregates, admixtures and bonding agents combined in controlled proportions to provide excellent adhesion properties, rapid setting and strength gain, as well as superior durability and reduced shrinkage.

    Xypex Restora-Top 50 is used for the patching or resurfacing of dete- riorated concrete up to 1/2 in. (12 mm) thick. It is used on surfaces where light traffic conditions exist.

    Could not find a price jet but certainly much cheaper. Fairing out is more difficult but perhaps I can imprint a kind of non skit during the drying prozess.
    I been reading about the membrane sealer and it looks this product is needed for floors at ground level to protect water from coming up. This is not the case on a boat.

    thanks and hoping to get more ideas

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