The basic concept of this boat was conceived to some extent in my mind when I saw the competition announced in the July issue of Yachting Monthly. But there was no time to put the design on paper - not until November 27! The closing date for the competition was 1 December. So for three days I worked night and day.

However, the term Night- and Daysailer does not refer to the time of the day when she was drawn, but to the way she is intended to be used.

A boat of this size is large enough to provide anything - speed, comfort, practicality, style, seaworthiness, security, and ease of handling. But she is not big enough to offer unlimited amounts of all these virtues.

The usual solution to this would be to make either a chubby little cruiser, just like a big cruising yacht, only smaller, or a pure racer or daysailer. A proper cruiser of this size means beam, high freeboard or coachroof, rounded hull-shape, weight, windage, limited sailing stability and a small sailplan. These boats are usually not very inspiring to sail, going to windward slowly, pitching at each wave. The racer is usually a futuristic creation, very GRP, with limited appeal apart from the sailing itself.

I have chosen to mate a classic small cruising weekender with a state-of-the-art racing keelboat that will offer unlimited fun. This boat should inspire both confidence and excitement, and she should be a pride to own.

Appearance

Constance* is a thoroughly modern boat. As I will explain, in some respects she is very much ahead of her time, aiming bravely into the new millennium. However, in her design, she is a tribute to some of the wonderful workboats and business-like cruisers of the soon past century.

The appearance is not for sentimental reasons. Traditional shapes have evolved slowly and are often the most functional. Constance has standing headroom (some!) where it is needed and good deck space elsewhere. The freeboard is highest where it helps to keep the boat dry, the waterline is long for the size of boat. This gives good speed potential, and the fact that the bow and stern are not burdened with the weight of overhangs is one of the keys to an easy motion.

Even the bowsprit is a traditional attribute. Only, in this case I stole the idea from contemporary racing boats. But unlike them, Constance’s bowsprit is run through the bulwark, as in the old days. This offers a few advantages, as I will describe later.

Making it all work

I have deliberately tried to stay away from the most spectacular concepts and brave ideas. The innovations in Constance may not be immediately apparent - they are there, sure enough, but the most important aspect of any design is to create a boat where all parts go together in a harmonious unity.

A few words about the drawings: Without the different plan views, sections and elevations it is very difficult to assess how a new design will work. How does the interior match the deck layout, is the boat buildable at its intended weight? This is especially important in small boat design because all measurements are so much tighter. So despite an almost desperate lack of time, I decided to make more or less complete sketches.

For series production, the hull should be hand-laminated using multi-axial stitched rovings on a closed-cell PVC foam core. Aluminium spars. (If cost is not strictly limited, a further improvement would be gained by building the hull according to a resin infusion process like SCRIMP, and by using carbon fibre spars.)

Hull shape

Science tells us that a boat’s underbody should be balanced forward and aft with its centre of buoyancy (L.C.B.) a slight percentage aft of the middle. The scientific results are derived from tank tests in calm water. But sailboats sail in the sea. When a sailboat sails against the wind it hits the waves moving in the opposite direction. The boat has an energy; the waves have energy, too, and the impact will slow the boat and start it pitching. Unless it has a very sharp bow.

You will see from the plan view that Constance has a relatively full, rounded bow shape. This is at deck level. Under water, she has a sharper bow than almost any boat of similar proportions. Her waterline entry angle is a mere 17 degrees. This means she has a buoyant and dry bow, yet will slice through the waves with ease in almost any condition.

Another effect of this hull shape is that since the L.C.B. is pushed a little further aft, the keel can go a little aft as well. This improves steering. And since a boat of this kind has rather full sections aft above the waterline (and rightly so because she needs a broad, flat stern for offwind speed) she does not alter her trim as much when heeled.

This is an aspect of hull shape which yacht designers are not generally aware of. The Delft tank test results are cited in the text books and have not usually been questioned.

Keel

The problem with an ordinary keel is it does not start to resist leeway until it has leeway. You may point 40 degrees towards the wind and end up at 43.

With the keel shape invented by the designer, as it was also used by the winning boats in the America’s Cup in 1992, this problem no longer has to exist. Gone is leeway, and at the same time, the keel produces less resistance.

The problem with this keel is that it involves one complication (a moving flap); this costs money and Constance is not an America’s Cup boat. So despite the tremendous advantages it offers, the new keel may have to remain an option.

Keel suspension

The keel is mounted in a carefully cast inner moulding inside an ordinary keel case which is fixed at its forward end to the main bulkhead. This arrangement, if engineered and built with care, gives excellent structural strength to the part of the boat which carries the greatest stress loads. The keel can be lifted for trailering, or for motoring into shallow anchorages.

To improve things a little further, as can be seen in the drawings, there is also an elastic bumper inside the keel case. With the right stiffness, this will allow the keel to move at impact. Even a slight movement will reduce the impact energy to a fraction, possibly eliminating the risk of damage entirely. To test, hold an eraser on top of a nail and hit it with a hammer. If you can make the nail move, I will eat my eraser.

Rig

The mast has a wide base for the shrouds. This allows for a thin and light section, and for single spreaders to be used. For a lofty sailplan like Constance’s , I do not think the rig could be made lighter, simpler or with less windage than this.

What sets it apart is the incorporation of a wishbone boom which, if it can be controlled in the right manner, is another of those rare ‘innovations’ that will not make the boat more complicated.

Ease the sheet, move the wishbone up the mast and you will have a deeper curvature and more downward pressure at the clew to control twist. Pull the sheet and pull the wishbone down a little, this will flatten the sail for upwind efficiency. Now the sheet pulls down to control twist. And the unusually long mainsheet traveller gives a huge range of adjustment for fine-tuning on the wind.

As a further bonus, the outline of the mainsail is improved, with a low throat and higher clew, and one gets rid of the boom. This is also a safety issue.

Constance should sail upwind at 6 knots and will surf at 10 or 12 knots when reaching in force 5.

Deck

As another safety matter, Constance has watertight compartments forward and aft. In order to avoid making holes into these compartments, the ‘bowsprit’ and the jib furling gear are mounted on deck. But these items need to be built-in to some degree, for protection.

The sunk foredeck provides a solution to this problem and, at the same time, makes it easier and safer to move on deck. Besides, it is easy to build, structurally sound and, since there is no bowsprit going through the bow, the interior will be dry.

Living onboard

The cockpit is more than 2 metres long and laid out for 1-4 people. The mainsheet is out of the way, controlled by the helmsman, which means the cockpit floor is unobstructed for sunbathing. There are two spacious lockers for cushions, perhaps a table, and other paraphernalia.

The interior forms a part of the structural integrity of the boat. I did not want to simply tuck in four berths inside a cramped interior but instead accomplish some more comfort, without adding kilos. There is a generous double forward with a deck hatch above to give light and ventilation. This compartment may be curtained off from the rest of the boat to give some privacy.

In such a small package boat, the large cockpit would normally restrict interior space. In Constance, it still does but not to the extent one might expect. There is sitting headroom under deck, extending all the way aft. This makes it possible to sit at least four people in reasonable comfort in the cabin. The visible part of the interior extends more than 4 metres (15ft) forward and aft and almost 2 metres (8ft) across.

Opening the cockpit hatches, a cabriolet-style canopy is revealed, extending across the transom; it folds out in seconds, the cockpit hatches are closed again and the cockpit becomes an integral part of the interior.

Engine and installations

An engine is needed to take you home when the wind dies.
Constance has a propulsion system which is completely silent, clean and odourless, and is at your service at the touch of the control lever. It reaches full thrust, 60 kgs, in less than two revolutions.

One of the beauties of this system is that it allows the incorporation of a full complement of things like electric lights, a music system, sailing instruments and even an 18 l (2cu.ft.) refrigerator, drawing less than 4 watts. The normal means of ‘refuelling’ is plugging in the cord. But for a longer cruise, Constance can even be equipped to be entirely independent of shore power and rely on solar cells.

The clue to the efficiency of this new system is in the speed control, the refrigeration technology and the optimising and integration of all the different components. It is not generally known, however, that the system has now been tried for several years and can be used for production boats.


Constance, specification:

Dimensions:

L.O.A. 7,29 m 23,9'
D.W.L. 6,60 m 21,7'
Beam, maximum 2,50 m 8,2'
Beam, waterline 1,96 m 6,4'
Draft 1,52 m 5,0'
Displacement, light 1270 kg 2800 lbs
Disp., equipped for cruising, ex people 1500 kg 3300 lbs
Ballast 550 kg 1210 lbs


Sail areas:

Sail area 100% 30,5 m 329 sq.ft.
Mainsail, true area 21,9 m 236 sq.ft.
Jib, true area 12,2 m 131 sq.ft.
Gennaker 60 m 650 sq.ft.


Ratios:

D/L 125
SA/D, upwind 26,0
SA/D, downwind 80
LYS 1,20
WL. entry 17°



* Why Constance? The competition was conceived with the new millennium in mind. You could say that this design spans the past, the present and the future. Therefore, it would be natural to focus on the passing of time and name the boat accordingly.

Yet, when being onboard some boats, I get the feeling that I could go on forever, that time becomes of no importance. –– Constance stands for the true values of life which don’t change much from time to another. Besides, she was Mozart’s wife