Building RYD-16.9 Rocky - Hull 21

Discussion in 'Boatbuilding' started by John Theunissen, Aug 5, 2017.

  1. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Many design simple combings and other things with easy to make bits, but I've always done rounded combings and stuff, simply because once you learn how to bend stuff, there's no need to live with boring. I've bent a lot of stuff over the years and developed plenty of techniques and preferences too. Sometimes you break something, but it happens to the best of us. It's the heat that really does the deed. Moisture just keeps the cellular structure from collapsing during the bend. My two go to tools are a standard heat gun and the steamer any more. I do have two different length traditional steamers, fed by a metal 5 gallon gas can over a campfire kettle cooker, but they don't get used very often any more.

    On your forward sections, steam the concave side first and if it's still fighting you, steam the other side too. I'll bet just steaming the concave side will be enough.
     
  2. John Theunissen
    Joined: Aug 2017
    Posts: 19
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    Location: Melbourne, Australia

    John Theunissen Junior Member

    Greetings,
    Slow progress due to other commitments. Last weekend my cousin and I had a go at applying a sanding sealer coat on the hull using 6” plastic straight line scrapers. We mixed in some fumed silica and that worked quite well. Took us a fair bit longer than expected so only progressed about 2/3 along the length of the hull. It’s one of those times where you wish you had acquired some plastering skills (as you can see from the imperfections (my side) after sanding back the high points on the first image). I had another go at filling in the “troughs” today and it looks much better (second image) but I guess the result will only be evident when I sand it back with the long board. Next time I’ll perhaps try the recommended technique of using a notched trowel for the first layer.

    Paul, I’ve acquired a steamer as you suggested but haven’t tried it out yet - perhaps next weekend, but it’s becoming really busy at this time of the year. It’s all about priorities, and the boatbuilding tends to take a backseat when there other things that need doing.

    Regards, John T.
     

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  3. PAR
    Joined: Nov 2003
    Posts: 18,645
    Likes: 381, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    What are you using as a "sanding sealer"? What I use is a neat coating of epoxy, to lock down what's there and seal the surface. This assumes she's reasonably fair first (you've already focused on seams and lap joints, etc.). If not, I long board the whole hull to identify obvious highs and lows. I knock down the highs and fill the lows (fairing compound like QuikFair) then long board again to see how good things got filled. Once the surface is close, then a building/blocking primer is applied, unless areas around high spots wore through the sealing coat (straight epoxy). If this is the case I'll touch-up those areas, or consider another whole boat sealing coat.

    With this prep done, the whole hull is "dusted" with primer and "blocked" with a long board and moderate paper, again to further identify highs and lows, which should be pretty sallow at this point. Usually, it just requires a few more rounds of filling with bulking primer, typically only in areas that need it. Once this is completed it should be pretty darn fair and I apply a final coat of primer as a continuous base for a top coat.

    FWIW, fairing and smoothing operations are not pleasant, no zen, just elbow pain and tedious motions, until it's right. Most eventually toss up their hands and say close enough, then wish they hadn't given up after the shiny stuff goes on. To be honest, it's tough for a novice to get a fair and smooth hull on their first few projects.

    I don't like the notched trowel method, because it's very difficult to sand down, inside the the notches, which has me wondering how good a bond you get, with unsanded fairing compound, which tends to be shiny when not sanded. Now this technique does help identify highs and lows well, but you apply a gallon of filler and sand off 80%, which is time and materials waste that I also don't like too. I haven't tested the notched bond thing yet, but it might be worth it, just to see where it'll fail and/or to change my "models" of the method.
     
  4. John Theunissen
    Joined: Aug 2017
    Posts: 19
    Likes: 1, Points: 3
    Location: Melbourne, Australia

    John Theunissen Junior Member

    Hi Paul,
    Thanks for your advice. I used the wrong terminology when I mentioned “sanding sealer” - what a am doing is applying the sanding compound to then fair the hull. I did use a longboard for most of the initial sanding (before applying the “fix-up” coat) but in the areas near the bow I used a smaller sanding block because of the curves. For the sanding compound I’m using the Botecote epoxy mixed with their sanding filler and some fumed silica.

    I tend to agree with you on the notched trowel approach so will not be using that. Regarding the perfectly faired finish, there’s no chance of me persevering to that extent, but I would like it to look reasonable.
     
  5. PAR
    Joined: Nov 2003
    Posts: 18,645
    Likes: 381, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    In stead of a block, use a smaller longboard, maybe one with a slightly more flexible board. 1/8" (3 mm) acrylic sheet or plywood makes a pretty flexible board, that you can attach some blocks to to hold the paper. Fairing is all about technique and if you do it enough, you'll get pretty good at it, depending how long your elbows hold up.
     

  6. John Theunissen
    Joined: Aug 2017
    Posts: 19
    Likes: 1, Points: 3
    Location: Melbourne, Australia

    John Theunissen Junior Member

    D2DE2E1A-681B-4ECF-A305-6F69A2B477E4.jpeg Fairing the hull is hard work! The sanding is going to take ages....time to inspan my sons during the holiday break if they are willing.
     
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