The Harryproa Concept

It has long been observed that the main requirements of any boat are space, speed and low cost, and that while any two of these are possible in a particular boat, all three are not. However, if you are prepared to sail a boat that looks different, and requires a slightly different tacking technique, it can be done.

Harrys are definitely different! They are also the least possible boat for a given length, which also makes them potentially the fastest and lowest cost.

A quote from one of the guys who skippers Blind Date, a 15m/50′ harryproa that takes blind people sailing:
‘Once you sail a good multihull, you never want to go back to a monohull. Once you sail a good proa, you find other multihulls somewhat limited.’ 

As soon as we pulled in the sail and the Blind Date accelerated, these sailors were convinced that they were on a good ship. They enjoyed the shelter and the view, a combination that no other boat offers like the Blind Date. They see the ‘logic’ and the simplicity.

We talked about the feeling of space and freedom that is in the Visionarry design. The spirit of the designer, I’d say.
Harrys consist of two unequal, double ended hulls joined by a pair of beams. The rig and rudders are in the longer, slimmer hull which is always to leeward. The shorter, fatter hull contains the accommodation, galley, cockpit and other home comforts and is always to windward.

To sail one, you need a rig and rudders that will go in either direction. Instead of tacking, you shunt. Release the sheet and when the boat stops, rotate the rig and rudders through 180 degrees. The stern becomes the bow and you sail off in the opposite direction. The crew does not have to move.

Proas and shunting are not new, Pacific islanders have been shunting their proas for thousands of years. What is new, is applying it to a western style boat, and placing the accommodation in the windward hull. When I started playing with proas in the 1990’s, this was considered impossible, as the experts were convinced it would have uncontrollable weather helm. My first harry was 12m/40′ and it sailed like a dream.

Features that make harryproas superior to cats and tris:


They are lighter: A cedar strip/fibreglass 15m cruising harry with 2 queen size bunks, 2 singles, galley, toilet shower, table for 6, sheltered cockpit and nav table weighs less than 3 tonnes. A similar cat weighs twice as much. The result is that a much smaller rig and motors are required, the materials cost is almost halved and everything becomes smaller, lighter and cheaper. The latest boats are built from infused foam/fibreglass. The skins are lighter, stiffer, and there is less of them as the hulls have flat bottoms so can be lower and don’t need fitted floors and the frames and stringers associated with them.

The hulls each have a specific task and are designed accordingly. The lee hull supports the rig and rudders and is long and sleek to provide speed and pitch resistance. The windward hull needs no structure to support rigs, daggerboards and rudders, so can be much smaller and lighter with a much wider choice of layouts.

The rig is unstayed and made from carbon fibre. This is about the same cost, weight and windage as a stayed alloy mast, but there are no chainplates, travellers, jib tracks, turning blocks, seagull strikers, spinnaker poles or all the beefing up and fasteners these things require. Instead, the area around the mast and between the beams takes all the rig, beam and leeway loads so is built very strong, and the rest of the boat, which has no rig loads, very light. By contrast a cat with forestay, sidestay and traveller loads has to be strong from fore beam to traveller, plus an immense main bulkhead to resist all the compression loads.

No daggerboards, keels or centreboards. Leeway is resisted by oversize rudders, usually mounted on the beams. This solves all the problems inherent in a bi directional boat and many of the problems of mono directional ones. The rudders kick up in a collision or grounding and can be raised for shallow water or downwind. There are no holes in the hull to grow weed, leak or be damaged in an impact. To quote Nol from Blind Date again “Upwind I usually sail with the rear rudder at less than a 5-10 degree angle. There is one point when you can feel the boat is hard as stone: no drift because of the rear rudder, hulls moving straight through the water. The front rudder is used only to make very small corrections. Sometimes minutes go by without any correction. It is like meditation.”

Very shallow draft. The 15m/50’ter mentioned above draws less than 300mm/12”. The rudders will steer the boat at slow speeds at this depth.

No extra sails. The only sails required are the two mainsails on a schooner rig or the main and jib on the ballestron rig. These provide enough sail area for light air and downwind, while the auotmatic depowering of the rig keeps the upwind loads managable.

Very little metal. What fittings there are, are made from composites, usually carbon tow. The same material is used to make very stiff, strong and light beams, rudders, masts and booms. Tow is a very cheap form of carbon, which helps keep the costs down.

The lee hull is only for storage, so needs no internal finishing. Bunks and cockpit seats are included in the windward hull building process. Therefore they do not need to be built, bonded and tabbed in place.


They are very safe and easy to sail. The crew sits in the sheltered cockpit on the windward hull, able to see most of the horizon, including the danger zone which is usually blanketed by deck sweeping genoas. They never have to venture outside the beams onto pitching, wet foredecks.
The full ends, no rocker, centralised weight and location of the crew makes for a much more comfortable ride. The skipper, crew and passengers are all able to sit together, with very little effort and no movement required for gybes or tacks.
Sails on an unstayed rig can be hoisted lowered and reefed on any point of sail in any wind strength. This is safer, and much easier than having to luff head to wind.
Shunting is not only easy, it is low stress and can be reversed at any stage. There is no chance of getting in irons, no flogging sheets or traveller cars to catch unwary fingers, no picking the right time or surfing uncontrollably down a wave.
In a person (or hat) overboard situation, the boat can be stopped in seconds and sailed back to them, then stopped again to get them onboard.
There are two types of capsize for cats and tris. Sideways, usually when an unexpected squall hits and no one is on the sheet and pitchpoling, when the boat surfs uncontrollably down a wave. On a harry, depowering in a squall is automatic as the mast bends, feathering the sail and lowering the centre of effort. This allows you to set enough sail for the lulls and let the rig depower in the gusts. Conventional rigs are set up the opposite way and/or require constant attention to the sheets. Downwind, the sails can be eased all the way forward to slow the boat in big waves.
More righting moment: Harrys typically have 60% of the total weight in the ww hull. Cats have 50%. So, a 3 tonne harry has the same righting moment as a 3.6 tonne cat or tri.


Harryproas are much less prone to pitching than cats as the rockerless hulls have very high prismatic coefficients (the ratio of volume in the ends to volume amidships) and all the weight is concentrated amidships, which is also the pitch axis and the location of the crew. The rig also has a lower centre of gravity than a stayed rig. Sailing upwind, the bows of the hulls tend to meet the waves at the same time. This results in a monohull like motion (without the heeling!) rather than the corkscrewing motion typical of a catamaran.


Because harrys don’t have to tack, the hulls can be optimised for speed and reduced pitching, rather than turning ability. This has resulted in rockerless hulls, which are also far easier to build.


Harry prototypes have been built from everything except steel and aluminium. The first non prototype harrys were built from cedar strip, a well proven method of building light, stiff strong boats with lots of curves. However, it is very time consuming, and requires huge amounts of fairing. The latest boats are built from infused foam, either from flat panels on a table, or in a simple mould. (See FAQS)The time savings over strip planking are from 50-75%. The costs are lower (less waste, able to use vinylester resin) and the boat is lighter for the same strength. But the biggest gain is the lack of mess and sticky, toxic materials. Infusion keeps the fun part of boatbuilding, while removing the drudgery.

The unstayed rigs could be used on catamarans to achieve the handling gains, but for reasons unknown, very few of them are. Equally, catamarans could be built from infused panels, but apart from KSS boats, none are. The advantages are not quite so clear cut in this case, as the cat hulls have rocker, so need to be cut and forced into shape, then glassed, filled and faired.