Boat Forum / Building / September 2005

My firt 8' dinghy job was formed over a saggy old wooden skiff. A
coat of wax paper, cloth, 2 or 3 layers of mat alternated with light
cloth, all done while green except for a break in the middle cured
overnight, rough sanded and washed with acetone in the morning,
followed by many coats of clear resin with like, 7 or 8 drops of
yellow pigment per mix. Just kept on mixing a coat's worth in a cup,
colour first, MEK next, paint it on, mix up, again, again,,, got the
speed mixed right to keep it all tacky, flowed on with an old brush
stiff and yucchy, squeegeelike, built up to about 1/16 thick self
levelled gelcoat, in an open garage in summer humidity. Filletted
inside corners with bog and a layer of cloth.  Strong as a cast iron
bathtub, stiff, with a little hogging between the centre and each
end, hardly noticable.  Planed at about 15 kt with me and a Suzuki
3.5 o/b on the flat.  I steered "with my chin", hung over the front,
leaning to steer. Great fun. Traded it away, wish I hadn't, now.

I don't think it matters much what weight cloth, it was all ad hoc,
I had some scrap and bought some at the local race track f/g works.
I watched them make apple barrels and learned to keep an airtight
ammo box acetone bath to clean tools, especially a washer roller I
made up from threaded rod and loose alternated 2 sizes washers with
locked nuts to squeeze out air between glass lams.

The boat was about 1/4" thick or less and included a luan floor to
hold down 1.5" styrofoam, 3 plywood seats sitting on wooden 2x2
clamps, screwed from the outside.  The gunnels were old plywood
strips, one in, one outside, screwed together and capped with a
layer of glass.  Shoulda been 2 or 3 layers. Coulda been nice
mahogany, routed to fit over the rough edge. It got tore up dragging
it over stones. I whittled knees for the top of the transom and flat
stem, leaving holes for rope, forming handles screwed from the
outside, and painted all inside with leftover beige latex. A plywood
motor mount doubler for the transom incorperated into the stern
thwart. Space under the seats for my "golf club" bilge pump clamped
onto stiff plasic pipe 4 feet long, using a bag phone battery and
flex hose discharge.  Putting the discharge under the water outside
the boat formed a syphon that meant the pump needed not work to
actually lift the water, it only worked to move the water sideways,
out of the boat. I used to go around the marina and pump out dingies
after a rain until the battery went flat, just for the hell of it.

They never found out it was me.

Couple of hundred bucks, then, altogether.

Fun.

If you cut holes big enough to pass curved through hull "nozzels"
with hosed clamped on and 5200 permanently glued to the inside, you
could route hoses to a "T" manifold assembly and valves, with pump
controller, or use the big nuts and clamp hoses on later if you have
ample room behind. Make sure hair, etc can't get sucked into a
recirculating drain and drown someone. Keep the pump intakes high on
the sides, and grated to protect your biggest pekker too, or use a
passive, nonsuction overflow collector, maybe perforated drain pipe,
possibly under a decorative, removeable side deck grating. Add a tub
/ shower surround kit, maybe some mirror tiles, and Bob is your
uncle. A timer on the pump would ensure eventual release of anyone
snared too far from the power switch. People have been drowned, dare
I say even worse, by recirculating spas.

I never heard of osmosis blister in fresh water, especially if the
tub is not always full.

Terry K

I don't think a university library will be much use .  The sorts of things
you need to know are exactly what Universities are NOT about.

I'd spend a bit more time on the web, looking at manufacturer's sites.  I'd
also do some careful cost estimates based on what you might end up paying
for appropriate materials.  Then double it for the inevitable learning curve
and wastage costs for the first time one- off, add another 100% for fixing
it sometime in the future ...   and compare this with what a commercial
product is worth.  You might decide it's not something you want to do.
Perhaps talk to a small commercial manufacturer, see if you can make a mould
and have them produce from it ...
David

Try to find "The Gougeon Brothers on Boatbuilding."  These are the guys that
developed and marketed West System epoxies and their newsletter has
described uses including lots of applications in swimming pools,
architectural stuff, etc.  As you might suspect, the book describes the many
boats they've built using all sorts of techniques.  Well written with lots
of pictures.  Their techniques work well with System Three products, but
don't tell them.  http://www.westsystem.com/

System Three gives away "The Epoxy Book" on their web site.
http://www.systemthree.com/index_2.asp
Free if you register and  download and print it yourself.  It covers much of
the same material in a lot fewer pages, but do read both.  (Skip the first
few paragraphs of The Epoxy Book if you really don't want to hear about the
chemistry.)

Roger   (I think S3 might have less blush than West, but then maybe I've
just been lucky.)
derbyrm@NOSPAMearthlinkNOSPAM.net
http://home.earthlink.net/~derbyrm