In theory drawing the bolts to check them sounds straight forward,
with most things with old boats it is not always so simple.
First thing, is to
determine the material and configuration of your keel.
The most common materials are
cast iron and lead, though
occasionally concrete and sometimes more expensive exotic materials are
Concrete ballast keels
although cheap and easy to cast,
can cause all sorts of problems later.
For a start because concrete
is so much lighter than lead
or iron, the ballast will have to be five to six times larger than a
The bolts are often cast into
the concrete making
And drilling for new ones is
fraught by the probability
that it has been filled with all sorts of scrap and reinforcing rods to
increase the weight and for stiffening.
The next ting to consider, is
the material the bolts are
made of and how they have been inserted.
Fortunately the most common
fastening method, the long,
vertical, through bolt from the bottom of the ballast to top of the
is also the simplest to deal with.
These will normally have a
large nut with a large plate
and washer on top of the wood inside and a countersunk bolt or forged
hidden behind a wood plug on the bottom.
They may also be bolted
through the wooden or metal
It is quite common to find
them in a row along the
centreline, it is however better if they are staggered.
But make sure whether or not
they are vertical, if the
ballast narrows towards the bottom they may be angled, this will affect
they are removed.
Bolts which have
galleried might cause problems when it comes to removal if they are
While galleried bolts will be
shorter, the problem is one
of space to work on the lower nut and the inability to drive the bolt
Bolts which have been cast
into the ballast, often found
in lead and concrete, cannot be removed, however they could be sistered
drilling new holes right through and fitting new long bolts.
That is another advantage to
the cast iron ballast, the
bolts won’t be cast in.
The number and size of bolts
holding the ballast will
depend on the it’s weight.
How the bolts are concentrated
however will depend on the
length of the mating surface.
The center of gravity of the
ballast needs to be balanced
longitudinally as well as laterally.
So, on a long keeled boat, for
instance the ballast and
therefore the bolts, can be spread along much of the length.
Where the forefoot is cut away
the ballast will have to
be concentrated nearer to the forward end of the keel, this will mean
bolts will need to be concentrated over a smaller area.
Rather than wait for the ballast to drop
off while you are
sailing, it is a good idea to make a few checks occasionally.
The most obvious and easily
spotted signs of trouble will
be leaks around the top of the bolts.
Whenever she is out of the
water examine the joint
between ballast and the keel for any signs of separation or
It is possible to get a rough
idea but it is only an
idea, of the state of the bolts by smacking them with a hammer, a sound
should ring whereas a corroded bolt will give a dull sound.
only way to
really know if a bolt is in good shape or not is to remove
Removing and examining one
bolt should give an idea of
condition of others, but it is no guarantee.
It’s possible that the huge
long bolt you have
removed is in perfect shape, but the one next to it has almost
The only way to
be certain is
to check and or replace them all.
Fortunately replacement does
not necessarily mean
removing the keel, unless the bolts are cast into the ballast.
Where bolts are cast in it is
possible, though very
expensive to have them X-rayed, except, of course for lead keels.
Unfortunately, the only other
way to check them is to
remove the keel.
If there are leaks around the
bolts but you are satisfied
with the condition of the bolts, this can be stopped as a temporary
packing below the nut and washer with caulking cotton and a sealant.
The first job is to get the nut off the top
of the keel bolt.
That is not always as easy as it sounds.
For a start the access may be restricted by the hull shape and
some may even
be hidden under the engine.
And they have been down there in the bilges for some time so,
probably corroded on.
If you have any
trouble at all with the nuts give
them a good soaking in penetrating oil.
Build a dam around the nut with modeling clay, you could even
use an old
bean tin with the top and bottom removed, fill it with the penetrating
leave it to soak for a few days, with an bit of luck some of it might
down the bolt. If that fails you could try using heat but be very
to start a fire.
As a last resort you may have to use a small cutter, a large
cold chisel and
a sledge hammer, to split the nut.
With the nuts off the fun really begins, rusted bolts in
hardwood can prove
very difficult to shift.
The usual process with through bolts is to hammer down on the
bolt with big
But first making sure that there is clearance under the keel
for the bolt to
drop, this may mean raising the boat up on its shores or digging a pit
Alternatively, if you haven’t got much clearance and are sure
needs replacing, you could drop it so far then chop it off then drop
Don’t forget to remove any bungs or filler covering the bottom
under the keel.
And it is best
to remove and replace one bolt at
a time, this will eliminate any risk of the ballast moving.
If you are just checking the state of the bolt and hope to
retain it, try to
avoid damaging the threads or creating a flange on the end as you
Filing a bevel around the top of the bolt before you begin
bolt is badly corroded in the middle or at the joint between the
wood keel or the dead-wood there is a possibility that hammering might
Or it could split allowing the top half to slide alongside the
Either way, this will not only cause a jam but will also
enlarge the hole,
it could even split the wood.
So, when you
begin hammering and the top begins
to move down check underneath to make sure that the whole bolt is
If it has broken in the middle then at least one of the ends
will have to be
Unfortunately it is difficult to apply pressure when trying
corroded bolts you could try a wrecking bar or block and
When the head of the bolt disappears below the surface, use a
drift to push right out.
The drift needs to he hardened steel so it is unlikely to bend
and a size
smaller then the bolt so it won’t jam in the hole.
An alternative to hammering the bolt down is to push it
upwards but this is
only possible if there is a bolt on the bottom which you can remove, it
not work if the bottom of the bolt is forged into a flange.
I am perfectly aware that the majority of Wooden Boat aficionados are sensible folk. However, I need to point out that I am an amateur wooden boat enthusiast simply writing in order to try to help other amateur wooden boat enthusiasts. And while I take every care to ensure that the information in DIY Wood Boat.com is correct, anyone acting on the information on this website does so at their own risk.