Introduction
This unconventional pocket cruiser is intended to meet the stated aims of the
Duckworks competition while making the best possible use of an adapted version of stitch
and glue construction using a system of tabs and slots conceived by the designer to ensure
a true and fair hull.
Particular consideration has also been given to the issues of seaworthiness - the fore and
aft 'turtlebacks' may remind some of the 'castles' seen in the highly respected Roamer
cruising dinghy, and have been used here for similar reasons. The result is a
particularly capable small yacht that will provide boating pleasure in security.
Two clear disadvantages of this approach are increased top hamper, and that the design
requires weight low down in the hull to provide sufficient righting moment in what would
otherwise be a top-heavy structure. Another problem is the difficulty of making provision
for auxiliary power in a craft like this; there is no room for an inboard engine, and
nowhere obvious to clamp an outboard, apart from the gunwale. However, I believe that this
can be answered by rowing the craft in a forward facing position, as in the case of Philip
Bolger's famous Dovekie camping cruiser.
It is interesting to note the similarities between this boat and those designed for
trans-oceanic rowing in recent years.
The hull
An unusual feature is that the hull is built in stages
from pre-cut parts designed to slot together. In the first stage of assembly, a
central 'keelson' is slotted to accept similarly slotted frames to form halving joints.
Tabs along the length of the bottom of the 'keelson' fit into slots in the bottom
of the hull to ensure accurate positioning; similarly, a slotted 'sheerstrake' holds the
frames in a vertical position. Once this structure has been horned and found to be
true, filled epoxy gussets produce a rigid 'eggbox' construction on which the rest of the
boat can be built with confidence. Further slots and tabs are used where possible to help
locate the remaining strakes.
As assembly proceeds, large areas of the original 'keelson' are removed as the increasing
rigidity of the structure renders it unnecessary.
The bottom of the hull is in half-inch ply; the rest is three-eighths.
A long opening in the top of the cabin roof will allow access to the foot of the mast and
bows fairlead for the purposes of reefing, furling sails, anchoring and fending off.
At just over 2 square feet in the water, the rudder is approximately in line with John
Teale's guidelines. (1) However, given the substantial
keel included in this design, it is not at all clear what the size of the daggerboard
should be; I have made a guess at just under six square feet. Nevertheless, this
boat's windward performance must be to some extent compromised by the high cabin roof, and
a longer board should be substituted if it is needed.
With a non-human displacement of 1400lbs, I calculate that ballast of 300lbs of water
stored in plastic jerrycans or the equivalent stowed under the bridgedeck should be enough
(in combination with the 128lbs weight of the half inch bottom and the 78lbs weight of the
keel) to make the boat substantially self-righting, based on the widely quoted supposition
that a boat will be self righting if 35 per cent of its weight is near or below the
waterline. (2)
The upper forward part of the forecastle, and the upper part of the stern castle are both
packed with expanded polystyrene for flotation purposes.
The rig
The rig is the gaff rigged cat-ketch arrangement, which
is widely considered to be the most appropriate for cruising. The mast can be
lowered easily to enable the boat to shoot bridges, and to help prevent capsize in bad
weather. For this purpose, the designer envisages that a tackle will enable the
forestay to be tightened from the cabin – a small footstep between the berths has
been included for this purpose.
The working sail area of 200sq. ft. is in close agreement with the figure given in John
Teale's guidelines for a vessel of 1800lbs. (1) However,
this design is not heavily weight dependent, and I believe it could be perform effectively
at displacements up to 2200lb
The rig is balanced for the cat-ketch arrangement; however, the designer feels that the
opportunity offered by the stay forestay is too good to miss, and so has drawn an optional
light weather staysail. This extra sail area may also provide a useful alternative sailplan.
Gavin Atkin, Tunbridge Wells, Kent 2000
References
1 How to Design a Boat. John Teale (auth). London: Adlard Coles, 1992
2 The Nature of Boats. Dave Gerr (auth). Camden, Maine: International Marine, 1995 |
