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We commissioned
this design from Dudley Dix in 2003.
CapeBoatWorks is the sole Australian Licenced
builder and Pre-Cut Boat supplier of the Cape Henry 21.
Cape Henry 21 – Characteristics
& designers notes provided by Dudley Dix.
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LOD 6.38m (20' 11")
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LWL 6.05m (19' 10")
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Beam moulded 2.42m (7' 11")
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Draft 0.495/1.34m (1' 7"/4' 5")
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Displ to DWL 1450kg (3195lb)
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Displ light 1160kg (2557lb)
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Ballast 520kg (1146lb)
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Waterplane area 7.56sq.m (81sq.ft)
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Immersion rate 77kg/cm (433lb/inch)
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Wetted surface 11.1sq.m (117sq.ft)
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Sail area (main + Genoa) 28.46sq.m (306sq.ft)
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Sail Area/Wetted Surface 2.56
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Sail Area/Displ 23.3
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Displ/length 184
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Prismatic coef .52
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Block coef .31
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Fineness coef .64
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Righting Moment @ 30 deg 523kgm (3780ft.lb)
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Righting Moment @ 60 deg 644kgm (4660ft.lb)
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Righting Moment @ 90 deg 303kgm (2192ft.lb)
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Mainsail 16.12sq.m (173sq.ft)
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Staysail 6.04sq.m (65sq.ft)
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Genoa 12.34sq.m (133sq.ft)
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Powering 6hp outboard
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The
lapstrake plywood Cape Henry 21 developed
naturally out of the Cape
Cutter 19, a GRP trailer sailer that
has become very popular in a short time and
has sold 70 boats in its first 2 years in the
UK market. The 19 proved to be a boat that is
full of character, able and seaworthy, with a
surprising turn of speed.
The appeal and success of that little boat
brought a steady stream of requests for
similar boats in larger sizes, to 30ft LOA and
beyond. The concept of the 19 will work in
slightly larger sizes but becomes less
practical as size increases. I chose to rework
the concept at 21ft to produce about 1/3 more
boat in terms of volume and displacement, with
resulting benefits in space, stability and
performance. Above this size, many prospective
owners expect standing headroom, which
requires considerable change in the concept.
The Cape Cutter 19 was named after the Cape of
Good Hope, where I have lived all my life at
the tip of Africa. The Cape Henry 21 is named
after the Southern promontory at the mouth of
Chesapeake Bay in USA, my home from January
2004.
The
hull is styled after the traditional sailing
craft of England, which have spawned many
modern interpretations of the basic concept.
It is lapstrake plywood in construction, with
carefully proportioned curves and strake
widths to produce a pretty hull. In lapstrake
hulls the chines are accentuated by the step
in the joint, so an unfair line looks very
ugly.
When I was designing the Cape Cutter 19 I
found that I could easily fair the chines in
my CAD programs but had problems visualizing
the proportions of the panels relative to the
overall profile and each other. I did not feel
confident of producing a hull that would look
good from all angles, so I returned to the old
steam powered drawing board to draw the basic
lines. After that I went back into the CAD
programs for minor tweaking of fairness and to
produce 3D rendered images so that I could
look at her from all angles. The result is a
boat that is attractive from wherever she is
seen.
The Cape Henry 21 is built over permanent
plywood bulkheads and has a plywood backbone
that runs from the stemhead through to the
start of the centreplate case. The backbone
and bulkheads interlock into each other
egg-crate fashion, making set-up an easy task.
This backbone provides longitudinal stiffness
to the forward part of the hull. The
centreplate case and a solid timber shallow
full keel, which runs through to the engine
well against the transom, provide stiffness to
the rest of the hull.
This hull is also stiffened structurally by
stringers at all chines. Although epoxy
filleted and glassed joints would have done
the job, it is more difficult to build that
way due to the panels flexing while shaping is
being done in preparation for the next panel
to be fitted. Professional builders have
probably got work-arounds for these situations
but my concern was to make the job as simple
as possible for inexperienced builders. I have
detailed stringers at all chines, which give a
firm base on which to work when shaping and
fitting panels. They also supply a fair line
for establishing correct shape and fit of the
panels.
Another concern was that a stringerless joint
has the strength to withstand the pressures
applied by the sea on the outside but not
potential loads applied from the inside. A
heavy person flopping down against the hull
when using the quarter berths as seats can
load the joint so that it cracks on the
outside, with potential leak and future
structural problems. A layer of glass on the
outside of the joint would strengthen it but
is not a simple task on a lapstrake detail. I
chose the stringer as the more user-friendly
option. Firm cushions fitted between the
stringers from galley to cockpit will allow
this area of the quarter berths to still be
comfortable as seats.
The
interior arrangement is a straight copy of the
19, with small galley, double forward berth
and quarter berths. The extra length gives
more foot-room to the forward berths and
enough length to the quarter berths to allow
Mom and Dad to sit comfortably after the kids
have turned in. A portable toilet lives under
the aft end of the forward berth and can be
screened with a privacy curtain.
The hull has good performance characteristics.
It is almost all waterline length, a sure way
of improving speed for a given weight under
most sailing conditions. It is fairly fine up
front at the first chine, with a hollow to the
curve of the waterline. This gives good
penetration to punch to windward through waves
and wind chop. Flare to the upper sections and
a broad forward deck give reserve buoyancy for
dryness and decent interior accommodation.
Aft she is quite beamy to make her forgiving
downwind. This also gives the ability to carry
the cockpit loads without excessive changes of
fore and aft trim.
This rig looks like conventional cutter but is
not intended to be sailed with both headsails
at the same time except when reaching. To work
well together with a staysail, the jib needs
to be a Yankee, ie a high-clewed high-aspect
working sail. Instead, this rig has a large
genoa on the end of the bowsprit for use as an
all-round headsail in light to moderate
conditions. It is set on a roller furler so
that it can be doused without crew having to
venture out onto the bowsprit.
The
sail that is tacked to the stemhead looks like
a staysail but is really a working jib for
heavier conditions. It brings the rig inboard
for safety when the weather gets rough. If
used as a staysail along with the genoa, it
will choke up the slot a bit unless the
heading allows sheets to be cracked off.
The bowsprit is hinged on the foredeck so that
it can be folded aft to lie along the deck
when not in use. This is most likely to be
done for access to tight moorings and for
trailing. The main forestay is the one to the
stemhead, so she can be sailed with the
bowsprit shipped.
The mast is hollow timber, fabricated by the
birdsmouth method. The mast is light enough to
be raised by two people without mechanical
aids. The boom is goose-necked to the
tabernacle rather than to the mast, allowing
the mast to be dropped without removing the
boom.
The mainsail is a high-peaked gaff, which
gives good efficiency without a topsail. The
low aspect nature of the sail plan allows her
to carry a lot of sail, more than is normal
for similar size boats with more modern rigs.
The result is surprising performance in light
to moderate conditions. There is also a
marconi rig option for those who prefer it to
the gaff rig.
Building
on the achievements of the Cape Cutter 19, the
Cape Henry 21 looks like also becoming a
popular little boat. Most builders will
probably build her from scratch but she is
available as a plywood kit from suppliers in
Australia, South Africa, United States and
Russia.
Most builders who take on this project will
learn some new skills along the way. That is
one of the reasons why we build our own boats
rather than buying. Any handyman of reasonable
ability should be able to produce a Cape Henry
21 of which he will be proud.
Visit
the Cape Henry 21 website; www.dixdesign.com/ch21.htm
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