Chart Board
For
a some time I used one of these “Portable Chart
Masters”. Here is a picture of the Portable Chart Master held by a bungee
across the companionway of Appuskidu in 2003 whilst approaching the Solent at
Frankly
sale of these things should be prohibited as they are not designed for a salt water marine environment. It is only the fact that you
can get a year’s use out of them which prevents customers from simply returning
them as not fit for purpose. The chrome plated steel clips start rusting after
a very few outings and using plated mild steel on an item intended to be used
at sea is just ludicrous. It is not too long either before the flap on the
clear plastic chart envelope cracks and lets the water in and the envelope is
not replacable.
The
task of making a replacement for Appuskidu finally came to the top of the jobs
list so I shan’t now have to buy another rusting Chart Master - ever.
This is the
finished result after one season of use and so far it is faring rather well.
The basics are a 6mm marine ply back board with a clear plastic envelope from
an Imray chart pack (It will take an Admiralty chart
pack envelope too) so that the clear plastic is replaceable. The envelope is
held firm on two sides (dark wood in picture), clamped at the envelope’s open
end by a hinged wooden flap secured by turn buttons (right of picture) and
tucked loosely on the fourth (top) side so that the envelope is free to expand
when a hand is thrust in to tidy a chart.
The two
clamped sides have “hockey stick” section stripwood from
the DIY store positioned and bolted down over a glued down piece of plain stripwood that is a thin enough to allow the nose of the
hockey stick to bear down on the clear envelope and hold it firm.
On the loose
tuck side, a wider piece of stripwood is glued on top
of the narrow piece so that the envelope can tuck underneath.
On the flap
side the flap is constructed from the same wide stripwood
but with a seal glued to the bottom edge so that when the flap bears down it
will seal the open end of the envelope even if the envelope’s own flap is past
its best. A strip of wood is glued to the top of the flap to act both as a
handle and as a stiffener since the flap can only be secured at the ends. If
the flap were allowed to bow in the middle the seal would be ineffective.
The hinges are
inexpensive rustproof nylon ones with stainless hinge pins. They are secured by
aluminium rivets with the countersunk heads in the hinges and peened over stainless washers on the top side.
The flap is held
down by turn buttons that bear on little pads cut from stainless sheet and
glued to the wood. Bostic “Serious Glue” was used for
the stainless pads to wood and the rubber seal to wood. Water resistant PVA wood glue from the hardware store was used for all the wood to wood joins.
The back of
the board is as free of projections as I could make it. The rivets and the
countersunk heads of the side clamping bolts hardly protrude at all. However,
the nyloc nuts of the setscrews on which the turn
buttons pivot protrude a little until I can arrange to reverse the fixings.