I write some brief notes about multihull rigs on the articles pages of my website. There I explain why the sensible choice for multihulls is the single mast bermudian rig, either masthead or fractional rig.

However many people want to experiment with alternative rigs so I thought these even briefer notes might help separate fact from romantic appeal.

Most alternative rigs are based on those used on various working boats in use round the world. However one must remember that, unlike recreational craft, which need to be good all-rounders, those boats didn't just sail, they fished, or traded. The actual voyage was just a means to an end.

The traditionally shaped gaff rig was often used by fishermen as it was easy to "scandalize" when dredging or trawling. It is still used today on the Falmouth working boats for that reason (they have to dredge for oysters under sail, engines are not allowed).

The Dutch trading boats used a short gaff and that is much more efficient, creating a simple "sawn off ellipse" shape. The resulting sail is very similar to the modern square top mainsails you seen on race boats and many multihulls.

The problem is that the gaff is much heavier than a batten. And the weight is in completely the wrong place so stability is reduced and pitching increases. The other problem is that to allow the gaff jaws to go up the mast it can only be stayed at the head, so it has to be a stiffer, heavier section with more air resistance.

The sail shape on a modern squaretop mainsail is designed in by the sailmaker, so there is nothing the sailor need do to control twist. On a gaff rig the vangs have to be adjusted, which requires skill and also more work for the crew.

The Bermudian rig came into being because the gaff rigs on racing yachts in the 1900-1920's became too big to be controllable with the materials available at that time. The triangular sail was much easier and had less loads. Even though people knew 100 years ago that it was in theory a less efficient shape the practicalities outweighed the theoretical disadvantages.

The Thames barge used a loose footed sprited mainsail. They used the sprit as a derrick when loading. The boomless mainsail could be brailed up when carrying lightweight but bulky cargo (usually hay for horses into London and horse manure back downriver to the Essex/Kentish farms). Few modern multihulls have to do that!

The Chinese junk rig was developed in part because they used split bamboo for sailcloth, which had little intrinsic strength.

Modern materials mean one can use different design techniques; it seems pointless to me to try to replicate something that was designed before better materials came along. After all, who now builds the interior walls of their house in wattle and daub, when sheetrock/plasterboard is better and easier, never mind cheaper? "Horseless carriages" didn't stay that way for long, they quickly became cars.

The lug sail and other "asymmetric" sails (so including the Crab claw and Arab dhow lateen rig) were rarely used in conditions where short tacking was a requirement. For example, the "Looe Luggers" were fishing boats developed near to my home port of Plymouth. Fishermen would sail out from Looe on a starboard reach to the fishing grounds off the Eddystone. There they'd lower sails. In the evening they would hoist sails again and reach back home on port tack.

A friend of mine rebuilt a Looe Lugger and initially rigged it with a lug sail. He only used it one season and then converted it to a gaff rig. Despite being very strong and fit he and his wife said it was just too much work to handle on a yacht.

The Pacific islanders fished in a similar manner. Out through the reef in the morning on one tack. Lower sails to fish and then back home in the evening. So a proa made sense for them. They didn't have to short tack up the Solent or try to sail down the ICW.

While I am talking about fishing boats, as a slight aside, fishing boats were often deliberately designed to roll, thus making it easier to haul pots on board in the days before powered winches, and the boat was "self jigging". So why do people think fishing boats must make good sailing boats?

Catamarans can have some unique rigs, the bimast one being obvious. But from what I have heard tacking them can be a problem. Certainly they are not very practical, on a reach one sail will be over the deck, making life on board difficult never mind obstructing the helmsman's vision, while the other rig is hanging over the side, completely inaccessible (even worse than on a monohull). Remember, one of the great safety advantages of a conventional rigged multihull is that the boom and sails are always inboard.

If a bimast rig, or a crab claw really was "better" (in every sense, ie handling, cost, efficiency) don't you think you'd see more of them around?? Unless you have money to burn, or are trying ideas on model yachts, it really is sensible to stick to conventional ideas.