frames of a wooden boat should be considered as part of her backbone.
When doing any restoration or repairs, checking
overhauling the backbone should have priority over any other joinery
Apart from determining the shape of the hull, the framing carries much
loading from the keel upwards through the planking as well as
especially amidships, over engines bays, centreboards, and maststeps.
A frame can be repaired by
fastening a sister along side the damage.
If the condition of the rest
of the boat is reasonable
sister framing can be a reasonable option.
However it is never more than
a holding strategy.
While it may be OK for lightly
stressed frames such as in
the ends those which carry high loads should be replaced
It is also difficult to tie
sisters to the floor timbers,
the deck and under stringers.
In a small, open boat it is
just as easy to replace, as
it is to sister.
In large boats, and cabin
cruisers replacement can be
more difficult especially where interior fittings and joinery work will
be removed for access.
However, replacing the damaged
ones with new, when
done properly, is, from the structural point of view, always the best
“To reach a port we must set sail – Sail, not tie at anchor Sail, not drift.” (Franklin D. Roosevelt)
Removing the old ribs from
an old boat without damaging the planking can be difficult if they are
the planking with layers of paint.
One method is to grind off the
heads of the fastenings on
the inside, then carefully pull the frame away form the planks.
Another method is to use a
skilsaw/circular saw to chop
them into short lengths, set the depth of cut so as not to damage the
and take care not to hit any fastenings.
Then carefully split the
lengths along the line of the
fastenings with a chisel.
Clean out caulking
particularly where there is any
deformation in plank curvature or where the seams are open so that the
frame will be able to draw the planks back into shape.
The strongest most stable frames are sawn from
suitably grown crooks.
Natural grown crook frames can
be found with a bit of
patience and searching in wood yards.
They can be made up from
pieces/futtocks with butt joints
or scarf joints.
However a butt jointed rib
will only be as strong as the
It is better if they are
double sawn, glued and fastened
with scarf joints
successfully been used in many boat building yards for many years.
It is an effective way to
produce curved timbers using a
minimum of lumber.
However for the amateur
builder or restorer it has quite
a few disadvantages.
Firstly the steaming
process is dangerous, that steam
The apparatus required, the
steam box, the seam
generator and all the piping is complicated.
The temperature is fairly
critical especially during
the last part of the process.
Over steaming will ruin the
structure of the wood.
Even normal steaming breaks
the wood down chemically.
The timber needs to be
green, the kiln dried lumber
normally found in wood yards these days is not suitable.
If you steam one rib at a
time you will have a long
wait between each, if you steam a batch then they will all have to be
place very quickly, before they cool or over steam if left in the
The wood could be just boiled rather
than steamed but
this again poses the problem of suitable apparatus.
I have heard of someone
using a hot air blower after
first oiling the wood, this might be useful for bending specific
You also need to bear in
mind that different woods vary
in their ease of bending when steamed.
Hardwoods such as elm, oak
and ash react well to steam
bending but many types of softwood are not suitable.
Here is an interesting
idea using a wallpaper
The time needed in the steamer
will depend on the
thickness of the wood, about an hour for every inch or 2.5 cm.
Don’t forget the loves that
wood is going to be
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.