Clamps or Cramps as you can before
starting work on your wooden boat,
It is perfectly true that you can never have too many and preferably of
sizes and types when boat building.
For all those major
boat building jobs its best to have good quality tools as
poor cramps can cause a lot of frustration.
However, there is also a place for even
plastic spring variety.
The more woodworking and boat
building you do the more
uses you will find for these versatile tools.
As an extra hand for anyone
To hold a straight-edge
while marking or
To hold pieces for accurate
To hold braces as you
To secure work while you
plane or chisel.
And of course for holding
And don't forget about the
'Spanish windlass' or
'G' cramps are the maids of all work,
they are robust, available in a range of sizes, easy to use, cheap and
A useful variation is the
'Edge cramp' which
has an extra screw in the centre of the 'G', these are useful
holding lips and curved surfaces.
The standard throat clearance
is sufficient for most edge
However, deep throat or long
reach versions are
Sizes usually refer to the
maximum size of piece which
can be held between pads.
These are meant to be
tightened by hand using the tommy
bar, using any greater leverage may damage the cramp and the work
They do have a tendency to
lose their buttons, these can
be pressed back on and secured using a punch.
Always use wooden pads to
protect your work.
The pads can be stuck
temporarily to the cup with a bit
of Blu-Tack while positioning.
gluing panels, for bulkheads, transoms and the like there is little to
reach and grip provided by a sash cramp.
These are available in a range of sizes with
the sliding jaw providing
rapid adjustment from the maximum length right down to zero.
The screw adjusted jaw is
fixed to one end of steel bar
while the sliding jaw can be positioned to suit.
There are various ways in
which the sliding jaw is
From the traditional simple
through pin, to a variety of Fast action, and cam cramps.
Some have 'T' section bars for
Some of the smaller
bar types are categorised as
They have the advantage that
they can be placed close
together as there is no need to allow room to turn the tommy-bar.
Also available are the fast
action type where both jaws
are movable, by tightening the screw both jaws lock and jam on the
Cramp heads are also available
which can be fitted on to
a wooden baton.
These are similar to the bar
cramps in principal, but using steel piping in place of the flat bar.
end of pipe is threaded to take the adjustable jaw, while the movable
be fixed anywhere along the pipe with either a cam action leaver or
clutch which tightens as load is applied.
Rugged hard working they
normally have shallow throats,
however deeper jaws can now be bought.
For some of those unusual boat
building applications the
pipe can be bent to fit.
Where that extra bit of
pressure is required when edge
setting planks, the pipe can be bent to fit the curve of the
the cheap and cheerful spring loaded cramps, the ones that look like
are immensely useful when you want an extra hand just to hold something
place while figure out what to do next.
The plastic variety with their
contoured jaws, to avoid
marking your work piece, have a surprising amount of clamping power and
easy and quick to position.
Use one of these when you are
sawing a plywood panel to
clip the end of the cut together, it will stop the ends flapping.
These are specially designed to
hold mitered joints together at right angles.
These are basically the vice
grip/mole grip tool that is in every tool box.
However there are deep
varieties which can be used
by the wood boat builder.
They can be useful when
However you need to be careful
of their immense clamping
pressures when working with wood.
When building a lapstrake
construction, tight clamping of
the lap joints is essential.
Traditional style lapstrake
cramps can be bought from
specialist tool suppliers.
However, they are simple to
By making you own to order you
can make them in whatever
size you need.
All you need are some hardwood
off cuts, some threaded
studding, nuts, wing nuts and washers.
And a scrap of leather or
webbing for the
Or instead of the 'hinge' use a
second length of
These are handy as the jaws
can be closed in a variety of
hand screw types are
similar and just as easy to
John Sheen's DIY Lapstrake Cramps
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