The AIR 40 is unique in many ways. The prime requirements were for a low cost, easily handled boat that would sail well in light air, be safe and easy to sail in heavy air and be suitable for the client and his wife to live on for extended periods. Secondary requirements were an open saloon that could be closed up and the ability to fit in a mono slip, a container or onto a trailer. Plus a tender that was capable of long trips at high speed in adverse conditions.


Length Overall: 12m
Beam Overall: 6m
Length Windward Hull: 9m
Draft Boards up: 250mm
Draft Boards Down: 1.1m
Sail Area: 60 sq m
Weight of composites: 820 kgs
Weight ready to sail: 1,000 kgs
Payload: 1,000 kgs (This can be increased if the excess goes in the lee hull)
Bruce Number at full payload: 0.61

(inc masts, beams, rudders and booms.  Does not include wastage, paint, consumables or safety gear)
400 gsm double bias fibreglass: 406 sq m
600 double bias fibreglass 180 sq m
440 gsm unidirectional fibreglass: 38 sq m
300 gsm uni carbon: 251 sq m
6 mm H80 foam: 9 sq m
12 mm H80 foam: 58 sq m
15 mm H80 foam: 32 sq m
20 mm H80 foam: 82 sq m
25 mm H80 foam: 19 sq m
Epoxy or methacrylate glue: 25 kgs
Carbon tow: 1 kg
Infusion resin: 178 kgs

Length Overall: 40′
Beam Overall: 20′
Length Windward Hull: 30′
Draft Boards up: 10″
Draft Boards Down: 44″
Sail Area: 645 sq’
Weight of composites:1,800 lbs
Weight ready to sail: 2,200 lbs
Payload: 2,200 lbs (This can be increased if the excess goes in the lee hull)
Bruce Number at full payload: 1.5

(inc masts, beams, rudders and booms.  Does not include wastage, paint, consumables or safety gear)
12 ounce double bias fibreglass: 4,360 sq’
18 ounce double bias fibreglass 200 sq’
13 ounce unidirectional fibreglass: 410 sq’
9 ounce uni carbon: 2,700 sq’
1/4″ H80 foam: 97 sq’
1/2″  H80 foam: 630 sq’
5/8″ H80 foam: 350 sq’
3/4″ H80 foam: 880 sq’
1″ H80 foam: 205 sq’
Epoxy or methacrylate glue: 55 lbs
Carbon tow: 2.5 lbs
Infusion resin: 390 lbs


The low cost was easy. Intelligent Infusion and the simple layout will allow it to be built very quickly, with little waste. The basic structure weighing about the same as a racing cat helps as well. Even the hinged beams, which would normally be very complex and stressful to build are “just another infusion” which happens to include the accurately aligned hinges.



Easy handling is a Harryproa trademark. The novel seating allows for three people to sit side by side on sheltered, comfortable, padded seats with all round vision, out of the sun and the wind and centrally located to minimise the motion. These seats rotate to face the table when it is time to eat. When the boat is folded, they sit in a recess in the lee hull. Steering is by tiller and the two mainsheets are close at hand. Shunting is far less onerous than tacking or gybing, particularly in adverse conditions and reducing sail is a simple task performed without having to leave the area between the beams. If required. it can be done with both sails completely eased, so the boat is stationary. This is far less stressful than trying to take in a reef when the boat is sailing upwind or the crew is on the pitching, exposed foredeck with flogging sails out of hearing range of the helmsman.



Light air sailing is frequently a lost pleasure in modern cruising multis. The Air 40 has 60 sqm of sail in two easily handled mainsail only rigs. These are self vanging and self stacking (no lazy jacks to catch as the sail goes up) due to the wishbone boom. The lightly loaded sheet controls the angle of the sail, the combined outhaul/vang and the flexible, unstayed mast control the shape. As long as the boat is kept reasonably light, it will ghost along in very low winds. In strong air, the unstayed shunting rig comes into it’s own. No scary jibes while surfing down monstrous waves with the mainsail crashing into the shrouds, no starting the motor and backing the headsail to ensure the tack is completed. Simply release the sheets, rotate the rudders, sheet on and sail off in the other direction. Sailing becomes the enjoyable, low stress affair it should be.



The simple layout has double cabin for the owner and his wife and another double for guests or storage. A large toilet space was chosen over 2 cramped ones. The galley is in the saloon, close to the table which will seat 8. The saloon has a raised roof with roll down clears so it is comfortable in winter and summer. The roof can be lowered if required for security or reduced windage. To lee of the saloon is the full length ‘toybox’ where fenders, lines, anchors, fishing fear etc are stored.

A 40′ cruising multi that can be traillered and fit in a shipping container is a challenge. As is fitting into a mono berth in a marina. The solution was to fit folding beams. These fold in the horizontal plane so could be made very strong, without struts etc adding drag and complexity. The hulls are not affected, so staying in a marina, without the long walk from an end tie, becomes more enjoyable. And cheaper. The folding mechanism is stronger then the beams, but only requires pulling 2 pins and pushing/pulling the hulls together to fold or unfold the boat.

The tender is not the usual blow up, impossible to row, difficult to stow, 3 adults max load at 2 knots inflatable. It is 5m long, with a powerful outboard capable of long trips at high speed in adverse conditions. It also serves as the motive power for the mothership. The tender lives between the beams, which is a much better location than davits on the stern. It is held in place by pins across the bow and stern. The stern ones are removed to lower the outboard into the water. The tender becomes a “sled”, with the advantage that it contours to the waves, so the prop never leaves the water. When the boat is folded, the tender fits under the bridgedeck. When the tender is away, the space is covered with slats, which roll up when not required.