Alan Lucas explains why he designed a boomless boat, and how to rig one.
When my wife and I designed and built our ‘ultimate’ boat in 1999, we had three positives: One, shallow draft: Two, a pilothouse instead of an open cockpit: Three, the possibility of gybing eliminated once and for all: The latter positive is reviewed here in the spirit of explanation rather than blanket recommendation.
The constant fear of gybing is part of a sailor’s life, its potential for catastrophic injury a constant companion when we are squared away and running swiftly before the wind. And even when a boom is restrained by a preventer, only fools believe it cannot fail and cause an unpredictable gybe. After a lifetime at sea, Patricia and I no longer wanted to risk sailing’s equivalent to being whacked on the head by a baseball bat: Thus our decision to banish booms from the rig altogether.
Our other decision, the pilothouse, provides a defensive bunker against errant booms but it does not negate the need to work the ship from the deck, which is a clash of ideals that still exposes us to the potential of a gybe: And so, ironically, by having a pilothouse we more than ever needed a boom-less rig.
And so, Soleares was rigged without booms, making sailing easier on all points except squared away, for which an entirely different rig was necessary. To this end, we added dihedral angled twin headsails (Diagram A), a friendly, docile rig I had used in the past on conventionally rigged yachts with great success. The resultant tedium of having to change rigs every time we square away or come to wind is inescapable, but tedium, we reckon, knocks the socks off debilitating cranial injuries.
If you are a racing buff, or a weekend sailor anxious to keep your life simple, none of the following will be of interest. If, however, you do a lot of coastal or offshore cruising and want the safest downwind rig ever devised, albeit, with a little inconvenience, then please read on.
Soleares is an unconventional ketch, her mizzen and mainsail being radical in their lack of booms. But having had a couple of ketches over the years, I knew that a mizzen sail is often furled downwind to reduce excessive windage aft and also because it can detrimentally interfere with the wind flow onto the mainsail. The real advantage of a mizzen sail is its steadying influence on the helm on most points of reaching, all of which is easily accomplished without a boom.
As for a conventional mainsail, when squared away its boom holds it out to the wind, making it an easily set and vital downwind force. To wantonly eliminate it was a tough decision to make but our commitment to adding a dedicated downwind rig made it practicable to fill its space with a mizzen staysail and main trysail, neither of which need booms and both are easy and quick to drop in a rising wind. Because a main trysail’s windage is up high in less troubled air it is more powerful than a mainsail for a given area and in light airs it can be replaced by a four-sided sail known as a ‘Fisherman’.
The main trysail is free setting, its single sheet passing through a block at the mizzen top and cleating off on deck below. We considered using a wishbone boom to keep it full when running downwind, but having a complex gooseneck out of reach aloft is a promise of unresolvable mechanical trouble so we accepted that it would collapse when squared away and, in any case, become redundant once twin headsails are set.
Initially, we tried free-setting the twin headsails but found them difficult to hoist and lower in strong winds so set up permanent twin forestays that run from the mast cap to each side of the trunk cabin a few feet forward of the mast step. On these two stays the twin headsails are hoisted as we turn downwind, their gull-wing form being set to a dihedral angle, meaning that the clews are forward of the stays and are held firmly in place by guyed poles goose-necked to the mast near its cross tree.
Onerous as it may seem, the changing from fore-and-aft rig to downwind rig is simple enough, as the following explains: Just like any conventional rig, all standing fore and aft sails function well in winds from forward of the beam to a point or two off the stern. Before they start collapsing when squaring away, all sails are progressively furled until just the main trysail is flying, under whose lee the first twin headsail is hoisted and the trysail is dropped. The vessel is then steered directly downwind and the second twin is hoisted, after which we revel in the safest and most benign running rig ever devised: namely, dihedral angled twin headsails.
Both headsails are permanently hanked onto their respective stays at the bases of which they are stowed in bags. When hoisted, their fore and aft guys are tied off to keep the poles firmly twenty degrees forward of their sails’ clews (a dihedral angle). Not only is this rig physically unable to gybe and hurt crewmembers in any way, it also produces a natural self-steering moment that powers up the windward twin and de-powers the leeward twin whenever the vessel tries to broach in either direction. The result is a straight-line course thanks to the natural self-steering dynamics at work (Diagrams B & C). These are so positive that the rig’s only danger is the way in which emergency collision avoidance becomes a tad more difficult owing to the twins’ resistance to
a course change.
Under dihedral twins, some vessels will steer themselves downwind with nothing more than the rudder locked amidships whilst others need the assistance of active aft guys taken through turning blocks to the tiller. And even on the liveliest of fin-keel hulls, steering is relieved to such an extent that an autopilot’s constant groaning changes to periodic whispering.
Alternative to the rig just described, twin headsails can also be set from the stem-head and poled out with their clews aft of the luffs like ordinary headsails (anhedral angle), but they depreciate in self-steering qualities (Diagram A). However, any twin headsail rig is much safer and easier on the helm than wing-and-wing mainsail and Genoa when running square, but the dihedral-angled system is top of the class in natural self-steering, making it the rig of choice for long-distance, trade wind sailing.
Alan Lucas is one of Australia's most respected sailing writers. He was the original editor of Cruising Helmsman magazine and his cruising guides to Australia’s east coast are carried on almost every yacht that ventures into these waters. He and wife Patricia are currently on board Soleares in Queensland, where they are updating the Coral Coast guide.