Wooden Boat Surveying
a wooden boat be aware that a
wooden hull is a complex structure.
Weakness in one area will have an effect on others.
When you are checking specific areas try to keep the overall picture in
Start by standing back, look at her from directly in front or astern,
she is symmetrical around the centreline.
Look from abeam to see that she doesn’t droop at the ends.
Every boat is different, so it’s impossible to give a definitive method
Let’s start by considering the materials.
Then have a look at some specific component parts.
Before a tree is cut down it naturally
conducts water soluble nutrients
up along the grain.
Normally the wood does not readily absorb moisture across the
Once chopped down and cut into planks it looses much of this
So it will only absorb moisture for a short distance along from the
in and then the moisture will advance further
causing more rot, ad-infinitum. rot
caused by fungicidal
micro-organisms which need moisture to survive.
where the timber has suffered from
splits in the fibers will make the wood more porous across the
As a result a plank can for no apparent reason rot from the
The wood of a boat is constantly being soaking in water, some areas
being alternately soaked and dried.
It is also being subjected to damage from micro-organisms, shipworms,
ants, termites as well as the normal stresses imposed on the
On top of that, all sorts of chemicals are allowed on to it, such as
spilled battery acid, diesel, detergents, and the like.
Yet despite all this there are still many old boats still afloat after
many, many years.
I wonder how many plastics boats will survive for as long.
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While most of a
wooden boat is made up of timber, it is all held together with
all subject to
Now, contrary to popular
belief galvanism is rarely,
really a problem with wooden boats.
The primary cause of most
corrosion to hull fasteners is
oxygen starvation, sometimes known as crevice corrosion.
This is caused by water being
trapped in a small,
confined space where there is little oxygen.
It occurs mostly, where metal
fasteners join two pieces
of wood together.
This wastage or necking as
it’s sometimes called,
usually begins at the center of the fastener at the interface between
pieces of wood.
This is where water will be
drawn into the seam by
Once the fastener has been
wetted a few times, it begins
Once the oxidization process
starts the capillary effect
attracts more moisture accelerating the effect.
At the same time because of
the lack of oxygen in the
cavity a chemical reaction turns the water acidic, which naturally
It is this acid corrosion
which shows up as pink and black on bronze fasteners and as a very
coating on iron and steel.
The only thorough way to check
fasteners for integrity
when surveying is to draw them out and inspect them.
Now this might be reasonably
simple to do with screws,
but where a boat has been nailed or riveted it becomes almost
without causing damage to the planks and frames.
The safest bet is to be
cautious, regardless of the age
of the boat or the fastening material.
However be doubly suspicious
of any form of steel
And when in doubt be prepared
to replace them.
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Wherever you start your
inspection the main areas to
check are the major structural members.
And you can tell almost as
much from surveying inside as
you can from the outside.
Check the keelson, the floors,
clamps stringers for any
signs of working, such as uneven scarph joints or any rubbing or
might indicate movement.
Use your screwdriver to probe
the keelson for any signs
Check visible bolts and bolt
heads for any signs of
corrosion or discoloration around the heads.
If the wood around the bolt
heads is soft this will
probably be a sign that water is getting at them causing serious
If your boat has an external
ballast keel and if there is
any doubt about the
they must be drawn and checked thoroughly. Keel
Check the transverse frames
and floors for signs of
rubbing or chaffing or softness.
Look at the mast base of a
keel stepped mast for movement
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are still surveying inside with that screwdriver in you hands, gently
especially where they are through bolted to the floors.
Any gap between planks and
frames or movement is a sign
of fastener problems.
Test the wood for softness in
the planks and frames near
their mating surfaces, especially near the keel and along the
ends split or the wood is
soft, they will need to be replaced or at the least
a special look at the frame in behind
for any cracks. bilge
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As well as
checking planks visibly, tap then with the handle of your screwdriver
wooden mallet, listen for any dull sounds.
Sound planks should ring, a
dull thud most likely means
rot or at best loose fasteners.
If you still haven’t bought
this boat be careful
not to cause any damage even if the plank is rotten, the owner may not
Look for discoloration around
the heads of any fasteners,
water stains and evidence of corrosion such as rust or green copper
On the inside, the
accumulations of dried salts will also
be evidence of weeping.
The two most common areas for
sprung planks to occur are
in the garboard and the forefoot areas.
Pay special attention to plank
ends, especially butt and
nib ends and the fasteners there.
‘Angle hair’ or shredded wood
caused by constant wetting with sea water and then drying. Salt
accumulating in the wood damage the wood cells.
However, if the damage is only
on the surface this can
easily be cleaned off.
Check seams for damaged
It is not uncommon for seams
to show signs of cracking
when a boat has dried out.
Providing the caulking
compound has not become hard and
brittle these should close up again when the boat is launched and the
Where the compound has become
brittle it will be worth
your while doing a complete
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are areas of high stress,
which are prone to leakage. Any leakage will endanger the fasteners.
Where the transom intersects
with the bottom and side
planking is another area where leakage and deterioration are likely to
Check for any open seams and
signs of rot on the
When surveying, pay particular
attention to any seams
that could allow rain water in, as fresh water can be disastrous for
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structural elements, they are not simply there to separate areas of
Any loose, rotting or other
wise damaged bulkheads must
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feel for soft or springy areas.
Pay particular attention when
surveying, to the areas
around fittings such as stanchions, any looseness will have allowed
Look inside for signs of leaks
on the deck head and under
the side decks.
Tapping with that screwdriver
or mallet will sow up any
bad spots, you will hear the difference.
A properly laid planked deck
relies on caulked seams, any
leaks here may result in water penetrating the substrate and the deck
for any signs of
weeping and rot. below
Where a deck has been covered,
be it painted cloth or
plywood panels, pay particular attention to the
Many so called teak deck are
veneered panels of plywood,
look out for delamination as well as seepage under the panels.
If she has a keel stepped
mast, examine where it goes
through the deck (the partners).
Check that the
sealing properly. mast boot
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and sea cocks, being metal are subject to the usual
and corrosion such as rust or green copper oxides, accumulations of
and the like.
If they have ceased up then
they need to be replaced or
The fasteners holding the sea
cocks and the sealant
between the metal and wood must be checked and preferably re-seated.
And while we are on the
subject of metal bits check the
pintles, gudgeons and other bits associated with the rudder.
Any worn bushings will feel
loose, there should be no
play at all in either a wheel or a tiller.
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