Learn everything about boats


Boat construction

A wide variety of materials andfoam or similar material is applied
materials are used in boat building:after the outer layer of fiberglass is
Wood - The traditional boat buildinglaid to the mold, but before the inner
material that was and is still used forskin is laid. This is similar to the
hull and spar construction. It isnext type, composite, but isn't usually
buoyant, cheap, widely available andclassified as composite, since the core
easily worked. It is not particularlymaterial in this case doesn't provide
abrasion resistant and it canmuch additional strength. It does,
deteriorate if fresh water or marinehowever, increase stiffness, which means
organisims are allowed to penetrate thethat less resin and fiberglass cloth can
wood. Rot resistant woods such as cedarbe used in order to save weight. Most
and oak are generally selected forfiberglass boats are currently made in
wooden boat construction. Glue, screwsan open mold, with fiberglass and resin
and/or nails are used to join the woodenapplied by hand. Some are now
components. Some types of woodconstructed by vacuum infusion where the
construction include:fibers are laid out and resin is pulled
Carvel, in which a smooth hull is formedinto the mold by admospheric pressure.
by wooden planks attached to a frame.This can produce stronger parts with
The planks may be curved in crossmore glass and less resin, but takes
section like barrel staves. Carvelspecial materials and more technical
planks are generally caulked with oakumknowledge.
or cotton that is driven into the seamsComposite - While GRP, wood, and even
between the planks and covered with someconcrete hulls are technically made of
water proof substance. It takes its namecomposite materials, the term
from an archaic ship type and is"composite" is often used for plastics
believed to have originated in thereinforced with fibers other than (or in
Mediterranian.addition to) glass. Cold-molded refers
Another method of building wooden boatsto a type of building one-off hulls
is lapstrake, a technique originallyusing thin strips of wood applied to a
identified with the Vikings in whichseries of forms at 45-degree angles to
wooden planks are fixed to each otherthe centerline. This method is often
with a slight overlap that is beveledcalled double-diagonal because a minimum
for a tight fit. The planks may beof two layers is recommended, each
mechanically connected to each otheroccurring at opposing 45-degree angles.
with copper rivets, bent over iron"Cold-molding" is now a relatively
nails, screws or with adhesives. Often,archaic term because the contrasting
steam bent wooden frames are fitted"hot-molded" method of building boats,
inside the hull. This technique is knownwhich used ovens to heat and cure the
as clinker in Britain and also as clenchresin, has not been widely used since
built.WWII. Now almost all curing is done at
Another method uses sheets of plywoodroom temperature. Other composite types
panels fixed to a frame. Plywood may beinclude sheathed-strip, which uses
laminated into a round hull or used in(usually) a single layer of strips laid
single sheets. These hulls generallyup parallel to the sheer line. The
have one or more chines. A type of thecomposite materials in question are then
plywood panel boat building methond isapplied to the mold in the form of a
known as the stitch-and-glue method,thermosetting plastic (usually epoxy,
where pre-shaped panels of plywood arepolyester, or vinylester) and some kind
edge glued and reinforced withof fiber cloth (fiberglass, kevlar,
fibreglass without the use of a frame.dynel, carbon fiber, etc), hence the
Metal or plastic wires pull curved flatfinished hull is a "composite" of fiber
panels into three dimensional curvedand resin. These methods often give
shapes. These hullls generally have onestrength-to-weight ratios approaching
or more chines.that of aluminum, while requiring less
Steel (and before that iron) - Eitherspecialized tools and skills.
used in sheet for all-metal hulls or forSteel-reinforced cement (ferrocement) -
isolated structural members. It isStrong and long lasting. First developed
strong, but heavy. The material rustsin the mid 19th Century in France. Used
unless protected from water. Modernfor building warships during the war.
steel components are welded or boltedExtensively refined in New Zealand
together. Until the mid 1900s, steelshipyards in the 1950s and the material
sheets were riveted together.became popular among amateur builders of
Aluminium - either used in sheet forcruising sailboats in the 1970s and
all-metal hulls or for isolated1980s, because the material cost was
structural members. Many sailing sparscheap although the labour time element
are made of aluminium. The materialwas high. The weight of a finished
requires special manufacturingferro-cement boat is comparable to that
techniques, construction tools andof a traditionally built wooden boat. As
construction skills. While it is easy tosuch they are often built for slower,
cut, aluminium is difficult to weld, andmore comfortable sea passages. Hulls
also requires heat treatments such asbuilt properly of ferrocement are more
precipitation strengthening for mostlabor-intensive than steel or
applications. Corrosion is a concernfiberglass, so there are few examples of
with aluminium, particularly below thecommercial ship-yards using this
waterline.material. The inability to mass produce
Fiberglass (Glass-reinforced plastic orboats in ferro cement has led there to
GRP) - Typically used for productionbeing few examples around. Many
boats because of its ability to reuse aferrocement boats built in back yards
female mold as the foundation for thehave a rough, lumpy look, which has
shape of the boat. The resultinghelped to give the material a poor
structure is strong in tension but oftenreputation. The ferro-cement method is
needs to be either laid up with manyeasy to do, but it is also easy to do
heavy layers of resin-saturatedwrong. This has led to some disastorous
fiberglass or reinforced with wood or'home-built' boats. Properly designed,
foam in order to provide stiffness. GRPbuilt and plastered ferrocement boats
hulls are largely free of corrosionhave smooth hulls with fine lines, and
though not normally fireproof. These cantherefore are often mistaken for wooden
be solid fiberglass or of the sandwichor fiberglass boats.
(cored) type, in which a core of balsa,



1 A B 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80