Cape Henry 21
This Cape Henry 21 was built by an amateur builder in Turkey.
The lapstrake plywood Cape Henry 21 developed naturally out of the Cape Cutter 19, a GRP trailer sailer that has become very popular and sold about 130 boats in the UK. The 19 proved to be a boat that is full of character, able and seaworthy, with a surprising turn of speed in light to moderate breezes.
The appeal and success of that little boat brought a steady stream of requests for similar boats in larger sizes over the next few years. The concept of the 19 works well in slightly larger sizes but appeals to fewer people as size increases. This is because of headroom expectations, related to the length of the boat. At around mid-20ft length owners are wanting more than sitting headroom and starting to look for standing headroom, even if in a limited way. Once over 32ft long, the concept comes back into its own because standing headroom comes naturally with that scaling-up process. The result is that I have now drawn boats in this series at 19ft, 21ft, 25ft and 32ft for clients and all are now available as stock designs for owner or professional building. The 19 and 21 are true trailer-sailers, the 25 can be classed as a maxi trailer-sailer and the 32 is just too big a boat to consider trailing other than on launch day.
The boat shown here is the Cape Henry 21, first of the series to be commissioned as bigger sisters to the Cape Cutter 19. The 10% increase in dimensions produces 1/3 more boat in terms of volume and displacement, with resulting benefits in space, stability and performance. Sail area increases 21% and stability increases by 46%, so the 21 has sail-carrying power to handle big winds. I designed the Cape Cutter 19 to handle the sometimes very boisterous Cape of Good Hope sailing conditions, a characteristic inherited by the bigger sisters.
The Cape Cutter 19 was named after the Cape of Good Hope, where I lived most of my life, at the southern tip of Africa. The Cape Henry 21 is named after the southern promontory at the mouth of Chesapeake Bay in USA, which has been my home since 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 visualising 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, an attribute passed on to the bigger boats as well.
Cape Henry 21 amateur project with the hull turned upright and ready for deck construction to start.
The Cape Henry 21 is built over permanent plywood bulkheads and a plywood backbone from 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. A bilge keel version is now also available, a benefit to those who need to leave their boats on tidal moorings.
The hull is 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 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.
Cape Henry 21 is being owner-built in Colombia. I met the owner at the Wooden Boat Show in Mystic Seaport, Connecticut recently. His boat is almost finished but he has to build a road to get his boat to the water.
This rig looks like conventional cutter but, in my original form, 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 Brits are traditionalists by nature, so it didn’t take long for the builders of the GRP Cape Cutter 19 to offer an optional Yankee, to make their boat a ‘proper cutter’. I followed that by also including a Yankee to expand the options in the sail plans of the bigger boats.
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.
Building on the achievements of the Cape Cutter 19, the Cape Henry 21 is also becoming a popular little boat. Most builders choose to build her from scratch, i.e. from plans only or plans and skin patterns. Aside from very detailed paper drawings, the stock plan package includes full-size Mylar patterns of all bulkheads, backbone and rudder, with patterns also being available for all of the hull, deck and cockpit skin panels, as an optional extra. Kits are also available from suppliers in various countries, cut by CNC router to a high degree of accuracy.
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. Almost all of those built to date have been amateur projects, producing some high-quality boats. Any handyman of reasonable ability should be able to produce a Cape Henry 21 of which he will be proud.
LOD 6.38m (20’ 11”)
LWL 6.05m (19’ 10”)
Beam 2.42m (7’ 11”)
Draft 0.495/1.34m (1’ 7”/4’ 5”) centreplate
Draft 0.7m (2’ 4”) bilge keels
Displ to DWL 1450kg (3195lb)
Displ Light 1160kg (2557lb)
Ballast 520kg (1146lb)
Waterplane area 7.56sqm (81sqft)
Immersion rate 77kg/cm (433lb/in)
Wetted surface 11.1sqm (117sqft)
Sail area (Main + Genoa) 28.46sqm (306sqft)
Sail area/Wetted surface 2.56
Sail area/Displ 23.3
Prismatic coef 0.52
Block coef 0.31
Fineness coef 0.64
Righting Moment 30° 523kgm (3780ft.lb)
Righting Moment 60° 644kgm (4460ft.lb)
Righting Moment 90° 303kgm (2192ft.lb)
Mainsail 16.12sqm (173sq.ft)
Staysail 6.04sqm (65sq.ft)
Genoa 12.34sqm 133sq.ft)
Powering 6hp max
Prop D Dix Dipl Yacht Arch (Westlawn) Dipl QS (UCT)
• South African born yacht designer Dudley Dix is a graduate of Westlawn School of Yacht Design. He has a wide range of designs, built by professional and amateur builders in 90 countries. The Dudley Dix Yacht Design office is in Virginia Beach, USA, with website at http://dixdesign.com