Conference unifix::sailing

    Well, there are steel, aluminum and ferrocement.
    
    Balsa and foam cores provide a more puncture resistant, stiffer
    hull than the same weight fiberglass. They also do not sweat and
    are much quieter. Exotic materials (carbon fibers, Kevlar, etc.)
    used in place of glass fibers in the GRP (Glass Reinforced Polyester
    - or fiberglass) can also provide greater stiffness and durability,
    but, so far, have been much more difficult for the shipbuilder to 
    master. They dont help with the noise and sweat either.
    
    Walt

    some one said that the Balsa cores get water logged and become spongy
    after a while. At the boat show the sales person said that never
    happens.? 
    
    
    I've seen aluminum fishing boats but not sail boats. What is ferrocement?

    Balsa can get water soaked if the GRP was improperly laid up and
    osmosis (sp?) occurs (water seeping thru microscopic pores into and thru
    GRP). Blistering is usually a first sign of osmosis and probably
    a bigger problem.  The core can also get wet if deck and hull hardware
    is not properly bedded, resulting in delamination and core rot.
    This is most common with reinforced decks which are usually cored
    with balsa or plywood (and where most of the hardware is mounted).
    I dont think hull delamination is very common.
    
    Stars and Stripes is aluminum (and other light alloys), as are nearly 
    all 12's (except some old wood ones and Kiwi Magic of course). There 
    arent too many cruising hulls out of aluminum. I suspect all are
    custom built.
    
    Ferrocement is a pleasant term for mortarmix over chicken wire (actually
    it is a waterproof concrete troweled onto a steel wire form). These
    are usually homebuilt boats. Some are very nice. Many have cruised
    for years. Some look like a bad dream. I dont think anyone makes
    them commercially (as in a production boat).

    Walt

    There is also 'feralite'. This is a process like ferro-cement, but
    using a poleyester resin insted of concrete. A wire frame is set
    up, then poly thickened with some powder is trowled on. A 45' herreshoff
    designed Mobjack built by the inventor of this stuff was just launched.
    
    The inventor is a most interesting fellow- Platt Monfort. He also
    invented and sells kits for ultra-light boats, an 11 foot canoe
    weighs 10 pounds. These boats have a ligh wood frame reinforced
    with kevlar fiber and covered in aircraft heat shrik dacron.
    One of his boats is now hanging in a major craft
    show in New York and has had photos in several magazines, including
    Fine Woodworking.

    I also recall a hard core beer drinker who made his hull out of
    old budweiser cans.  A waterproof covering made from the plastic
    rings was placed on top of the cans. 
    
    You can believe it, I saw it on television.  :-)
    
    Rick

    This may not qualify as an alternate 'material', but it's certain an
    alternate METHOD - it's called "cold mold", and it is essentially a
    process by which the hull is actually a single molded sheet of plywood. 
    I know at least one outfit that builds these hulls commercially.  I
    believe they use a male mold, over which is stapled layers of 1/8" KILN
    dried cedar.  The kiln drying is significant, since the very low
    moisture content permits the wood to really soak up the resin that's
    used to bond the layers.  The resin they use (WEST system), is claimed
    to have a expansion and elasticity properties that are very close to
    those of wood, so that the materials don't work against each other.  In
    any case, layers of the epoxy-impregnated cedar strips are layed up in
    alternating directions.  The result is supposed to be very strong and
    light.  The only down side that I've heard is that it's very difficult
    to repair.

    Well, I like wood for several reasons, though I recognize there are
    severe drawbacks in terms of amounts of work and money.
    
     One reason I like wood, is because I can remove and replace any part
    of the boat. I, personally never permanently attach any two pieces
    together (i.e. I don't glue frames to planks, or nail the sole to the
    floors). The downside is that it takes lots of effort, and some skill
    to replace a plank, or frame. If you look at a wooden boat, you'll see
    that the structure is actually fairly simple to understand.
    
     Another drawback, in my own conscience, anyway, is the fact that I
    am using trees. Teak comes from rainforests.I assuage the bad conscience, 
    somewhat, by buying oak saplings and planting them someplace where I
    think  they will be safe from foresters.
    
     Gregg