Utility Hull Finish

Discussion in 'Boat Design' started by DouglasEagleson, Feb 22, 2016.

  1. DouglasEagleson
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    DouglasEagleson Junior Member

    In the old days the yacht club wood hulls were perfect mirror varnish surfaces always. And the reality of moored hulls was painted surfaces of non-perfection.

    With gel coat fiberglass finish now every body begins with perfect mirror hulls. I was adding up the cost of gel perfection and it thee dominant cost of hull making labor.

    I would like to define the term "utility hull type". Use various non smooth fiberglass hulls direct from female mold. No gel coat. And then use hull surface treatment of desired selection.

    As an example I propose spun surface. Take a disk sander and make a surface treatment like a metal machinist would. The cost saving is dramatic. Mirror gel finish makes the average boat cost yacht club finish.

    So the term "utility hull" is to means heavy design with spun surface. A flat epoxy paint would ensure the design as sans intention to impress, just work. Work at boating. It is a hideous thing to train or fined a human hull sprayer. The whole cost structure revolves around mirror sprayers. With mirror molds.

    When you take the cost saving and make thicker hulls for displacement designs the benefit is obvious.

    The skin friction change is real but small. Wavy bottom paint appears the dominant surface distortion.

    Human sprayers do artwork.
  2. Mr Efficiency
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    Mr Efficiency Senior Member

    You don't like things sh*te and briny, Doug ? There is little doubt recreational boaters like to impress with slick looking boats, but commercial and fishing boats are frequently "rough as guts", and the expression "handsome is as handsome does" is the ruling principle with those people.
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    FAST FRED Senior Member

    A smooth finish is a no cost item from a smooth mold.

    Creating an unfinished crap surface mold would not save much over the 100+ hulls a mold can pop out.
  4. Mr Efficiency
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    Mr Efficiency Senior Member

    They would be unsaleable, but have the virtue of being non-slippery if the boat was overturned and you were clinging to it.
  5. PAR
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    PAR Yacht Designer/Builder

    Yeah, the key here is can you sell it, which compaired to the common gel coat finishes, which are usually quite smooth, but not especially fair, well not much of a business decision frankly. When you put a shiny, smooth finish, next to a less than finish, what do you think the percentage of prospective buyers will be?
  6. philSweet
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    philSweet Senior Member

    Your perception is from the perspective of the amateur. For the professional with skill, access and funding, it is not that much harder to get a good finish. The finish is usually chosen to be just hard enough for the amateur to duplicate that it forms a real barrier to entry, but not so good that it is a real headache to pull off. Then the marketing people make sure it becomes the standard of public acceptance.

    Believe me, its a long running joke that folks buy those lovingly perfected hulls and promptly go roll about 6 coats of goop on it with a 3/8 nap roller.
  7. DouglasEagleson
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    DouglasEagleson Junior Member

    Thanks for the perspectives. I will test it out to see what it looks like. A "spun" surface is the word I will use. It would just be a choice for the final finisher.

    I am planning planning for a dinghy kit. It is to be a 10 long one. I will supply a one layer of woven roving hull using polyester resin. The basic hull provides the ground works for a family project.

    They get to finish and add seats and flotation and deck as desired. Also a dagger board box if for sailing also.

    I am debating what accessories to sell. A daggerboard box? Foam? MAS composites? Mast? Sail? Rudder?

    One true law of mine is re-entry of the flooded boat. How is minimal flotation of the contemporary dinghy supposed to be reacted to? So my design will be a decked foot hole style boat. Just like sailboats. There is a true danger to going beyond swim to shore passages.

    The finish work is left to the builders. Maybe just add a cloth for the surface. Then sand. Making the cost left to the builders. I will demonstrate my concept.

    I will hopefully demonstrate how to get an autobody shop to finish sand and paint.

  8. gonzo
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    gonzo Senior Member

    That would be a really rough finish. An acceptable finish for a workboat would be #400 grit. That should be easy to accomplish with a DA. Fairing takes most of the labor involved in making a plug. The extra effort to sand the grind marks may be no more than a couple of hours. For a production boat that is negligible.
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