Rig Options - Balestron

Whatever the rig's advantages for tacking craft, they pale in comparison to what it can do for proas; it makes shunting as simple and stress-free as tacking your Hunter 32 around the bay. This rig makes single-handing a big proa a reality, and opens the door for proas to become a serious alternative for the cruising sailor.

Easy Rigs

by Rob Denney

What is an EasyRig?

An EasyRig is a copy of the rigs used on model boats to reduce deck gear and sheeting loads, and to improve efficiency with eased sheets. It was first used on big boats by Marc Pajot on his 15m (60') tri Elf Acquitaine. It was commercialized by Carbospars who have since built over 100 rigs. [Ed Note: Carbospars went out of business several years ago] A few years ago, I asked CarboSpars (I had previously worked and sailed with the owners) for a license for Australia. They weren't interested, so I built a rig for a little 5m (16') cat which worked wonderfully. I then built and sold them for a while.

Easyrigs consist of an unstayed mast (generally, but not necessarily, carbon) carrying a main and jib. The main boom extends forward of the mast (the mast passes through the boom) to the tack of the jib. The main and jib are sized so that the force from the mainsail is slightly higher than that from the jib. That is, the combined center of effort is just behind the mast. The angle of incidence of both sails is controlled by a one or two part, lightly loaded sheet. When the sheet is eased, the main moves to leeward, and the jib luff to windward. The slot remains the same, the rig remains at it's most efficient. There is no need to adjust jib tracks, or sheets, main travelers, boom vangs or halyard tensions.

The advantages of an EasyRig for a proa?

Ease of use. Once hoisted, there is no trimming required, except for changes of wind direction. This is achieved by pulling in or easing a single, lightly loaded sheet. The center of effort is only slightly aft of the mast, so aligns closely with the centre of resistance. When shunting, there is no need to raise and lower sails, move the rig or the crew, or alter the location of the water foils. To the best of my knowledge, no other set up can make these claims. Easy Rigs have now been used on proas up to 12m (40') long (Harry), where crew weight movement (either deliberate or inadvertent) has little effect, unlike on beach proas, where balance deficiencies are easily overcome by crew movement. On Harry, I can shunt single-handed in 8 seconds, using almost no energy at all.

Being caught aback is a potential drama on most proas. With the EasyRig it is a nuisance, but no more. The backed rig weathercocks to face the breeze and the boat stops. Judicious use of the sheet and the rudders soon sees it back on course. As with shunting, passengers probably won't be aware that anything has happened. There is far less hassle than on a conventional marconi rig when caught aback.

Most sailing is done short handed. With only a lightly loaded sheet and a steering wheel or tiller, crew are redundant. This is probably the biggest drawback of the EasyRig, everyone except the helmsman is bored!

The sails are hoisted and lowered with the rig facing into the wind, regardless of where the boat is pointed. The hoister is only lifting the weight of the sail, not fighting the breeze and associated friction of the slides or luff rope. Apart from lazy jacks (removable) there is nothing to catch the sails on the way up, or down.

EasyRigs are reefed the same way as conventional marconi rigs. Either by slab reefing or roller furling. The difference is, that the EasyRig can be eased until it is pointing directly into the wind, thus reducing loads and effort required. Because the mast flexes at a predetermined wind strength, reefing is less necessary. With all sail lowered, there is considerably less drag from the mast than from a conventional rig with all it's wire and spreaders.

A well set up EasyRig will perform upwind almost as well as a constantly trimmed racing marconi rig, and at least as well as any other type of proa rig of similar area on any other point of sail. The ease of adjustment of the rig means that changes are made much easier and therefore more often than on a conventional rig.

Extras can be flown on an EasyRig, but because of the automatic poling out of the jib downwind, they are less necessary. If extras are required, they can either be tacked to the bow and sheeted to the stern of the lee hull, or tacked to an extension on the jib end of the boom, and sheeted to the mainsail end. In this case, the main sheet would need to be attached to the front of the boom. The sheet loads would increase sufficiently to require multipart tackles or winches.

In light, shifty air, it is not uncommon for the breeze to change direction by a large amount. With an EasyRig, the sail will work with the wind from either side. Tacking could not be any easier; there is nothing to do, except steer. This is not recommended in strong wind unless the boat has been designed for it.

EasyRig Costs

The initial cost of a carbon mast is high, although nowhere near as high as mast manufacturers would have us believe. The price of carbon is falling, the cost of setting up to build a mast is not high. A competent amateur could build his own mast for less than the cost of an alloy extrusion with all the required standing rigging. The mast on Harry (12m, 40' long, 90 mm 3.5" diameter) cost me $1,300, plus a mold, which I already had, but which could be built for about $1,000. Add to this $200 for a days hire of a compressor or a vacuum pump and contact heaters plus another $100 for high temperature vacuum bag and sealing tape and insulation, some old carpet for resin/air bleeding and off you go. Adding a track, hounds, mast head and bearing races use almost no material, but take a bit of labor.

(All prices are in Australian dollars. At the time of writing, this was worth a bit more than 50 US cents and 35 p sterling. That is halve the numbers for $US, divide by 3 to get pounds.)

On smaller boats, there is nothing to prevent an alloy or timber mast being used, with a shroud to the weather hull to keep the weight and windage down. My 5m (16') proa had a 50 mm (2") alloy mast with shrouds to the ends of each hull. Worked well, until you got caught aback, when, unless you were quick, the boom would be held by the shrouds in the fore and aft line of the boat, which would either depress the weather hull , or break the mast. Once the steering was sorted out, getting caught aback was a rare event, so we never bothered with this scenario. What eventually broke the mast was flying a hull in 20 knots, when the wind got under the sailcloth trampoline and turned what was usually a gentle capsize into a violent one, sufficiently so to shear the mast at deck level.

I have built high and low tech EasyRig booms. The weight saving is significant, but as it is low in the rig, it is not as critical as the mast. Harry's boom (ply, pine and glass) weighs 35 kgs (77 lb.) and cost a couple of hundred bucks. In carbon/foam it would be about half the weight. The boom has to be wide enough to fit around the mast, and deep enough to resist the jib luff and main leech loads. These are large, and any deflection in the boom immediately shows up as forestay sag. The other advantage of a deep boom is that it doubles as an anti-capsize device, similar to the pods on a lot of proas, but without their enormous drawbacks (weight in the worst possible place, huge drag when immersed, impossible to right the boat if it does capsize over the pod). The EasyRig boom and the sealed mast will stop the boat going past 90 degrees. The front end of the boom can then be lifted, the aft end submerges and the boat flips upright. I have not yet tried this on Harry, but it worked a treat on the 5m (16') prototype.

The main cost saving is the lack of gear associated with the rig. I built all the pulleys (glass sides and axles with plastic sheaves) on Harry, and use cheap cam or horn cleats as the loads are so low. There are no winches, tracks (except for the short jib track, easily made), jammers or large diameter expensive ropes. There is also no standing rigging, and almost no running rigging. Because of this, and the exceptional fatigue properties of carbon and wood, there is almost no maintenance required, nor anything to wear out. This does not apply to the sails, which will be the most expensive part of the rig, and probably the boat. However, with nothing to rub against and little or no flapping they will outlast those on a conventional rig.

A proa such as Harry is far lighter and easier driven than any other boat with comparable speed (7 knots with 5 horsepower outboard) or accommodation. This is partly due to the layout, but also to the fact that all the rigging loads are concentrated at one point. This point needs to be strong, but the rest of the boat only needs to resist water loads. The weight and cost savings from this are enormous. Consequently the rig can be much smaller. This is cheaper and imparts much lower loads to the rig and the boat.

The EasyRig is also an excellent teacher about sail trim and aerodynamic centres. The Carbospars rigs are very tall, with little roach on the main. They have relatively small jibs, which implies the main is pretty inefficient. They have about a 3:1 ratio, main to jib. We tend to use much roachier mains (largest was a 1m (40") square top on Harry) which are much more efficient, resulting in a jib of half the size of the main (a 2:1 ratio) being required for balance. The large roach provides a very simple means of balancing the rig, by easing or tightening the leech of the main. Another option is to initially make the jib boom over length, and experiment with moving the jib to achieve balance. The extra bit on the end is also handy for flying extras from.

Rob Denney designs and builds proas at Harryproa.com

The Mi6 Proa Rig

by Malcolm Smith

The Mi6 Proa (pronounced 'em-eye-six'), resulted from a 1993 design competition sponsored by System Three Epoxy and Modern Boating magazine. The Mi6 design was the eventual winner out of 80 entries from Australia and abroad.

We opted for a balanced or 'swing' rig to reduce sheet loads. The rig plugs straight into the mast box of the main hull, in much the same way as a Laser rig does, to allow 360 degree rotation. The rig uses a wishbone boom to which is attached both the clew of the mainsail and the tack of the jib. The mainsail is similar in appearance to that of a sailboard except that it runs in a conventional mast track for ease of rigging and reefing.

The jib is an unusual delta-shaped 'lop sided hang glider wing'. There is no jib sheet and the slot is trimmed by adjusting the clew position with a simple control line. The sail plan is of modest area for ease of handling. The mainsail has a large roach to improve it's efficiency.

Pros

Very quick and easy to shunt. It is similar to the balestron rig except that:

• It is cheaper and simpler to build in that it can be built from low to medium tech materials.
• Forestay tension is not a problem because it has shrouds.
• It can be adapted to use a rotating wing mast if desired.

Cons

It is not possible to move the C of E forward or aft significantly. It is probably more expensive than a blue polytarp crab claw rig (although with a bit of imagination, anything is possible).

I feel it is important to get the idea across because this rig combines the best features of the stayed and the freestanding balestron rig as per your definition. The rig is essentially freestanding, in that it is stepped through the deck in bearings that allow it to rotate through 360 degrees. The stays however, allow any type of main mast to be used, and ensure good forestay tension.

There are three components to the mast: a 6' stub mast, a set of spreaders at the top of the stub mast, and a standard aluminium tube mast above that. The short stub mast, which is the bit that goes through the deck, is solidly and strongly constructed. The spreaders, which are also fairly solidly constructed, are attached to the top of the stub mast, 4' above the deck. Above this is the main mast which is a standard 60mm O.D. x 2mm wall tube, tapered at the top in the standard aluminium mast fashion. The two are connected with a hinge pin so that the mast can be easily raised, using one half of the boom as a crane. The stub mast can be left in position in the boat even when the boat is being towed on the trailer. The boom is (now) a two part diamond shaped wish bone. The fore and aft parts of the boom are connected, at the centre, to the ends of the spreaders.

The stays are connected only to the mast and not to the deck, and so do not affect the rotation of the mast. At the base of the mast, the stays are attached to a collar which is also the thrust bearing preventing the rig from falling through the deck.

The idea is that the solid stub mast/spreader/boom arrangement acts like a rotating deck on which can be stepped any type of main mast you like. No carbon fibre is required for this rig, and you could make it out of bamboo and polytarp if you really wanted too. Despite the solid construction of the stub mast, the overall weight is quite reasonable because the wishbone boom is very light. Also, the centre of gravity of the rig is low because all the weight is concentrated at the bottom.

More information on the Mi6 proa project may be found at: Cybernautics

Comments

• Great article on proa rigs.  The MI6 rig description is very interesting but the link is out of service.  Any idea where I can find out more details about this rig?

  Thanks!

  Posted by  on  12/20  at  12:03 PM

• Hi Tim, Mal’s new URL is: http://members.optusnet.com.au/mal.smith1/mi6.html I’ll update the link.

  Posted by Editor  on  12/20  at  12:38 PM