Specifications:

Loa 15m/50'
Beam 8m/27'
Racing weight (preliminary) 550 kgs/1,213 lbs
Sail area 33.6 sq m/403 sq'
Hull surface area 46 sqm/495 sq'
Draft 1.16m/3.8'
Air draft 11.9m/40'
Bruce number ready to race 1.84
Bruce number no crew or safety gear 2.4
Hull flying wind speed (theoretical, without allowing for mast flex)13 knots
Wetted surface:sail area at rest 3.6
Wetted surface:sail area hull flying 4.1
Materials cost to sailing stage $AUS/15,000/$US11,250*
Labour cost to sailing stage $Aus25,000/18,750*
Hours to sailing stage 385

*prices correct in Nov 2006

 

15m/50' long, 8m/27' wide with a preliminary race ready weight of 550 kgs/1,213 lbs, half of which is safety/navigation gear, food and skipper. It fits in a container, needs no winches and in theory is self righting. Solo harryproa is a radical boat, but most of the features have already been tried on a half size model which I have sailed for the last 12 months. see http://www.harryproa.com/Elementarry/SailingPhotos_4.htm

The solo boat is a response to the ever increasing complexity in yacht racing, which not only makes it ridiculously expensive, but far harder work than it needs to be. It reverses the normal spiral which leads to more weight and more sail area. By removing weight, the stresses go down, followed by the size of the components, followed by the sail area required which lowers the stress, and so forth. To make this a success requires some fairly imaginative innovations.

Some of the features are;

Sheltered crew. Most short handers get up every 20 minutes, put on their damp wet weather gear and go outside for a look around the horizon and to tweek the sails and the course. They then go back down below, remove the wet gear, get back into bed and try to get back to sleep before they are woken again. Alternatively, they doze, huddled into a corner of the cockpit, wet and uncomfortable, getting very poor quality rest and unable to see what is going on. On the solo harryproa, the skipper can sail the boat, keep a look out, navigate and cook from the comfort of his bunk. The bunk is between the beams, so the sailor lies athwartships. He can sit up and reach out through the overhanging companionway to reach the sail and steering controls, or roll over one way to cook, the other to navigate. The top of the cabin is a wrap around piece of polycarbonate, allowing 360 degree vision from the sitting position. The piece of bunk extending across the cabin is removable, allowing standing headroom. This is a one person boat for overnighting, although a tent could go on the trampoline for family camp cruises.

Main sail only rig provides a far less complex boat (no winches), which is much easier to sail and saves huge amounts of weight and money. It is only possible because the boat is so light. Because the sheet is lead directly from the boom to the windward hull, being caught aback is impossible. As with all harryproas gybing and tacking are easier and safer than with a conventional rig. This is a little slower, although for singlehanders there is probably not much in it.

Unstayed wing mast. The major cause of boats not finishing yacht races is gear breakage. Harryproa's mast eliminates over 50 individual items (stays, turnbuckles, clevis pins, mast and deck fittings, spreaders etc), all of which must be checked on a regular basis, and the failure of any one of which causes the rig to fall down. No stays also eliminates crash gybes and enables the entire rig to be completely depowered on any point of sail. Reefing is required less often as the rig flexes in strong gusts, and when it is necessary, the boat can be stopped, making it a far simpler and safer job for the single hander than fighting flogging, partly filled sails.

May self right after a capsize. Because the sealed mast is canted 7 degrees to leeward and is in the lee hull, the boat will only capsize to 83 degrees. When capsized, the boat swings around until the mast is pointing into the wind. The combination of the offset ww hull weight and the windage will right the boat, in which case we have the world's first self righting, unballasted multihull. If not, it is a pretty simple operation to add a little more windage or weight (water) without the skipper leaving the cabin in the windward hull.

Another advantage of the canted rig is that the boat will have positive stability until about 80 degrees of heel, depending on wind strength and trampoline drag. At this angle the heeling force from the sail is minimal, so capsize becomes much more difficult. The rudder is well clear of the water and there is nothing to stop the boat sliding sideways on it's flat topsides. It should be noted that this theory also applies to the smaller boat, which I capsize regularly! The difference is the relative weight of rigs and windward hulls, I think. The canted mast is also very helpful in twisting the heavily roached sail in light air.

The rig weighs 50 kgs and it's centre of gravity is 5m above the waterline.
The ww hull weighs 326 kgs and it's cog is 0.55m (the heavy gear sits on the floor) outboard of the righting axis.
The surface area of the ww hull and the top of the bunk which are exposed to the breeze when capsized is 3.55 sq m and it's centre is 7.4m above the water.

So, with no breeze we have 50kgs x 5m (250 kgm) holding it down and 326kgs x 0.55 (180 kgm) lifting it up. The difference is 70 kgm holding it down.

Assuming the surface of the ww hull has a drag coefficient of 1 (the hull will be less, the bunk top more), and that drag is calculated by multiplying surface area x coefficient x wind speed (meters per second, 1 m/sec is near enough 2 knots) squared x the density of air (1), then the 12 knot breeze which capsized the boat will exert 3.55 x 1 x 6 x 6 x 1 = 128 Newtons= 13 kgs. This is applied 7.4 m up adding another 96 kgm of lifting force. The boat should self right!

Adding to the down force will be water on the sail, although it should be possible to lift most of the sail out of the water using the main sheet. This will also have the desirable effect of keeping the mast head pointing upwind as the boat rights.

Adding to the up force will be the windage of the beams and trampoline, plus possible help from waves lifting the mast and increasing the distance of the cog of the ww hull from the rotation axis. This is a big mass acting on a short distance, so any thing will be helpful. Reducing the up force will be the speed at which the boat is drifting. This will probably be 1-2 knots, but could be reduced by a sea anchor. The up force could be further increased by unrolling a sheet of cloth down the trampoline and there is 20 kgs of buoyancy at 2m distance (40 kgm) in the boom if it could be sheeted so it was submersed.

If we assume that the flexible rig means capsize does not happen until 20 knots windspeed, the up force increases from 96 kgm to 277 kgm. At this wind strength, the boat should self right even if the mast was vertical. The half size version has a hull lift wind speed of 12 knots and actually flies a hull in 20 knots, so this is probably a fair assumption. It does not self right as the pocket luff sails fill with water.

Single rudder, no keel or centreboard. Careful placement of the rudder, combined with the rockerless hull shape means that both leeway prevention and steering can be done with a single foil. This is mounted on the beam, with a traveller system so it can easily be moved to the other end. This is a huge weight and drag saving over the 6 water foils on a modern trimaran, plus the board is mounted in a box so it can be lifted for down wind work. Mostly though, it is a safety feature. In the event of hitting something (another common reason for curtailing a race), the board kicks up clear of the water. There are no sharp blades sticking through the bottom of the hull, and no boxes to leak.

Construction: As well as light weight, solo harryproa also has far less frontal area, (a major cause of drag) and side area, (a major cause of leeway) than any other shorthander and a higher power to weight ratio than most. Despite this, it is a low tech build. The hulls are built from low cost carbon and Polycore, a recyclable, tough, plastic honeycomb with a scrim bonded to the surface which ensures an excellent bond, without vacuum. Because the hull shapes are simple, the hulls are built from flat sheets with carbon on one side. These are rolled into cones, then squashed to the required shape and laminated on the other side . Not especially pretty, but minimalist, quick and cheap and with carefully located rebates, mean minimal fairing.

Timetable The boat will be launched next winter in Perth, Western Australia where it will have 6 months of debugging in one of the world's windiest cities. It will then be disassembled, placed in a container and shipped to San Francisco for the 2008 solo TransPac (San Francisco to Hawaii, June 2008). If the Transpac is a success, the boat will be sold and a new one, optimised for upwind sailing and the added safety gear required, will be built and shipped to the UK for the single handed transAtlantic (OSTAR) the following year. Containerisation is possible because the bows of the boat are not highly loaded (small volume , no forestay). Therefore, it is a simple job to cut 1.5m off each end, and glass them back on. Reassembling takes a couple of hours (mostly lacing on the tramp), plus a day for the epoxy, paint and antifoul to cure.

Because it is so light and simple, solo harryproa material costs are $AUS15,000/$US11,250* to sailing stage. Labour is another $AUS25,000/$US18,750* if built by Harryproa in Australia. Safety and navigation gear could add another $Aus11,000*, but by hiring the big ticket items such as liferaft, EPIRB and ssb radio it should only be half this. Shipping to any major port is about $5,000* for a container, but 5 boats could fit in a single container. *prices correct at Nov 2006

My boat has no electronics and minimal electrics. This is partly as I am not good with technology, but more importantly to save weight and cost and keep it simple. 2 x handheld gps, minimal chat on the ssb, LED nav and internal lights and the compulsory 120 amps of batteries will mean that a solar panel will provide all the power required. Therefore, there is no need for a generator and it's fuel, weight and problems. Despite decades of development, autopilots are still the least reliable bits of gear on sailboats, as well as consuming a lot of power. Harryproas are directionally very stable and have plenty of deck space, so a simple wind vane on a long (3m/10') arm should keep it on course. The long arm has the added advantage that, when sailing upwind, the weight of the arm will cause the boat to luff when the hull files.

With a single sail on a flexible mast you don't need to know in what wind strength different combinations of headsail and mainsail are most efficient. If the hull is flying too often, you need to reef. Hopefully a barometer and observations of the clouds will enable me to keep on the windy side of the North Pacific high pressure system, which is the dominant weather feature of the Transpac.

Transpac is an off the wind race. Mainsail only rigs are usually at a disadvantage in these conditions as they cannot hoist extras. I have had a lot of success with Outleader kites and will carry a 90 sqm one on 2mm spectra lines for the race.

The Transpac will be my first solo race, although I have plenty of offshore experience (6 Syd Hobarts, 10 years as professional skipper, 50,000 offshore miles), in multis and monos.

Transpac is not a high profile race, this year they only had 16 entries, mostly 9-12m displacement monos. 2008 is the 30th anniversary, should be a lot better. It is probably the most exciting, laid back yacht race available. Strong reaching conditions for a couple of days, then light air, then gradually increasing breeze from behind, culminating in big swell surfing along the north coast of Hawaii, it is run by a very friendly group of people who think proas are wonderful. OSTAR is the opposite. High profile, lots of boats, some professionals, bashing your brains out into cold storms the wrong way across the north Atlantic. Run by the Royal Western Yacht Club, who are still smarting over a bunch of experimental proas not finishing races 40 years ago, and not sure whether they want proas in their races.

Rob Denney