How to handle a cat in heavy seas - Soundings Online

How to handle a cat in heavy seas

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Editor’s note: Following two fatal catamaran capsizes this winter, we asked multihull expert Gregor Tarjan to discuss heavy weather catamaran tactics.

Q&A

Editor’s note: Following two fatal catamaran capsizes this winter, we asked multihull expert Gregor Tarjan to discuss heavy weather catamaran tactics.

Is a sea anchor or a drogue better suited for use with a catamaran?

This will depend on the sea room. A drogue will simply slow you down, whereas a sea anchor will literally moor you in the middle of the ocean with minimal drift, yet leave you crippled against a rogue wave from a different direction. Again, it is control that one is looking for. Using a drogue, or any other means of slowing the boat to be in sync with the seas, will create much less stress on boat fittings than a sea anchor, since one would be running with the wind and seas — always a better tactic on a cat. A drogue also can be used if you lose steerage, and by adjusting the tie-down point on the stern by a bridle, the vessel can be jury rigged to get you home.

Is there a method of deploying a sea anchor from a catamaran that differs from a monohull?

In addition to keeping chafe to a minimum, the most important aspect in deploying a sea anchor is the ability to control the angle, or attitude, the vessel will have to the wind and prevailing seas without putting too much strain on fittings. Usually a bridle system is used, whereby the individual arms are run via massive turning blocks or snap shackles to winches. The catamaran’s wide beam will give her an advantage over the monohull, as the greater bridle angle will reduce strain and improve attitude leverage, which facilitates boat rotation in respect to the sea anchor. It should be noted, however, that sea anchors should be used as a very last resort on a catamaran. In storm conditions, wave patterns aren’t always the same, and the odd rogue wave slamming beam-on could have dire consequences. If the cat is tied to a sea anchor she will not be able to dissipate the shock, other than being thrown on her sides. A monohull would theoretically right herself after a roll.

When running, either with or without a drogue, should a cat be taken straight downwind or angled off the waves as the folks on the Lagoon 380 did?

It is more advantageous to run downwind at a slight angle, as this will increase the effective length of the cat by presenting its diagonal distance (the distance from the port stern to the starboard bow), which is longer than the overall length of the boat, to following seas. This diagonal distance is the most important aspect of multihull stability. By running at a slight angle the bows of the multihull will bury less, and the risk of pitchpoling is minimized. The drogue can be deployed if there is a steering failure and/or to reduce speed to manageable velocities to be in sync with the wave pattern.

Does it make sense to run off from a storm with minimal sail in a catamaran?

Running before seas and wind with minimal sail is my preferred tactic in dealing with the very big stuff, if there is room. I remember a three-day winter North Atlantic Force 10 system that we ran before under triple reefed main and small Solent on a 64-foot cat on one of our trans-Atlantic crossings. We never once touched the helm, as the autopilot was doing its job flawlessly. Our cat’s twin non-yawing, always-vertical rudders and keels kept the boat on track, making it much easier for our autopilot to cope with seas.

What is the effect of high winds — not taking into consideration sea state — on a catamaran, and does that differ from a monohull?

Reducing windage is a considerable factor in successfully dealing with storms. The power of the wind on a structure increases by the cube of the wind speed. In storm-force winds of 55 knots, air pressure on your vessel will affect her ability to cope with the conditions. Superstructures on cats can be substantial, and although this has benefits in terms of buoyancy and habitability, many of today’s cruising catamarans will be less aerodynamic than the average monohull. This disadvantage, however, is often offset by a cat’s twin keels or daggerboards, which help tracking, and the lack of heel or roll, which facilitates boat handling. It should be noted that there are very well-designed, sleek cats out there that are not only beautiful looking but also rival any monohull’s windage. My brother, who is a business jet pilot working in Europe, always reminds me, “Gregor, what looks good, probably flies well.” I apply the same principles to cats.

Does the length of a catamaran affect its ability to survive monster seas?

Absolutely. Length makes a huge difference. In terms of seaworthiness, length is more important than any other factor, all things being equal. As long as the crew can handle the boat, a cat with a longer waterline will be able to combat high winds and towering seas easier than a smaller one. The motion will be easier, facilitating crew maneuvers; boat weight will be higher, resisting being tossed about by wind and convoluted seas; and usually speed will be greater, which will aid in running and tracking before the storm. In a short-handed, heavy-weather situation I would rather be in the longest catamaran I can handle. On the downside, longer boats will be associated with higher loads, so if you experience a gear failure, dealing with a broken system will challenge all of your single-handed seamanship skills.

Are the catamarans sold for island cruising and chartering suitable for crossing oceans, any more so than some production monohulls are unsuitable for bluewater voyages?

In today’s catamaran market, as in the monohull world, one can find vessels more suitable for serious long-distance voyagers versus ones that would make better coastal cruisers. To mind come the many notable French production catamarans, such as those built by the world’s No. 1 cat builder, Fountaine Pajot. [Tarjan’s Aeroyacht dealership sells Fountaine Pajot multihulls.] In the last 30 years its good-looking and capable cats have safely crossed oceans on their own bottoms to be used as either private or charter yachts. With many thousands built, these well-constructed and -designed European vessels have probably racked up countless open ocean miles — possibly more than all other production multihulls combined. An offshore-capable cat must not only be well-designed but also expertly built, as stiffness is more crucial with a multihull than a monohull. Overall beam-to-length ratio should not exceed 53 percent, and bridge decks should be as high off the water as possible. Aerodynamics of the coachhouse are just as important. Boxy-looking boats should be avoided (and there are plenty). They will present dangerous vertical surfaces to wind and breaking seas.

Are catamarans inherently less seaworthy or stable in heavy weather than monohulls?

Seaworthiness really is a combination of seamanship, boat design and construction. Whereas a monohull often can fend for herself in a storm, a multihull will require more attention. Higher speeds and loads will demand a vigilant crew who need to “dial-in” the catamaran in order to find the safest and most comfortable setup. Fortunately, fast catamarans have an edge in speed over equal-length monohulls and can often avoid bad conditions by smart weather monitoring and routing. The stable platform of a cat will also fatigue the crew less than on a monohull. Catamarans are far stiffer than keelboats because of their immense righting moment, which is many times that of a monohull. In fact, the stability of a wide-stance multihull is so great that, technically, a shroud would fail before the wind pressure alone could turn the boat on its side. A monohull would heel, roll uncomfortably, and spill the wind. Finally, a properly designed cruising cat is unsinkable, sheltering the crew in a catastrophic event, whereas the monohull would disappear from sight, forcing the crew into a tiny rubber raft. Maybe this is the “ultimate” answer to seaworthiness.

What design features improve the chances of a catamaran resisting a capsize in huge, breaking seas?

Well-designed systems, such as reliable steering and adequate buoyancy, are as important as a catamaran that is not too beamy. Too much beam and a multihull will become stable athwartships but less so fore and aft. It is the diagonal stability of a catamaran that is most important to consider. Very few properly designed cruising cats capsize. If they do they will likely pitchpole (flip stern over bow), and this is mostly a matter of seamanship error. Full bow and stern sections and centered weights will be imperative in preventing the bow from digging into a steep wave face. Catamarans often are overloaded, which will reduce bridge deck height and make them more sluggish. In the end, it is the skipper who will master his ship and assure the safety of vessel and crew. A well-built and -designed boat will only assist him or her in overcoming the worst the sea has to offer.

Gregor Tarjan has performed dozens of offshore deliveries and trans-Atlantic crossings, racking up 80,000 miles in 30 years of sailing monohulls and multihulls. He has crewed under such sailing icons as Dennis Conner and Yves Parlier on boats ranging from America’s Cup yachts to 120-foot monster cats. Tarjan also is founder and president of Aeroyacht Ltd. of Long Island, N.Y., which specializes in sail and power catamarans. His recently published book, “Catamarans, Every Sailor’s Guide,” is available on Amazon.com. This summer, Tarjan will attempt to break the New York-to-Bermuda record in his Blubay TC45 power cat. For sponsorship opportunities and more information call (800) 446-0010 or visit www.aeroyacht.com .