Ocean Sailing Basics

We've noticed that a lot of non-sailors, lake sailors, and coastal sailors are coming to YachtPals to learn more about ocean sailing, and particularly ocean racing. With the Volvo Ocean Race underway and Vendee Globe race coming up, we realized that there were a few general concepts many are unclear about, and we thought that we could make things a bit more understandable for our readers with a brief glossary. Feel free to print this out and hand it to people when they stare blankly at your watercooler stories of some boat "sailing along the rhumb line and pitchpoling during a gybe."

What is "Tacking?"

Sailboats cannot sail directly up wind, they have to take an angle on the wind, usually about 45 degrees or so. So, in order to go upwind, a sailboat must first go a little to the right of the wind, and then a little to the left, creating a zig-zag line. Each turn in which the bow of the boat crosses through the wind is called a tack. When sailors complain about how many times they had to tack, it means that they had to turn through the wind several times in order to make headway or forward progress.

 

 

What is "Gybing" (Jibing)?

To gybe (jibe) is the exact opposite of tacking. A gybe is when the stern of the boat crosses through the wind, and it is one of the more dangerous maneuvers on a sailing craft. When tacking, the forces on the sails are basically nil while the boat heads into the wind. When gybing, however, the forces remain constant, and the sails must be tended to prevent damage to the boat. One of the most dangerous situations on a boat is the "accidental gybe," when the stern crosses the wind without the crew being prepared.

Many sailors, when in bad conditions or when short-handed, will prefer to turn all the way around and actually tack through the wind rather than gybe. This is called a "chicken gybe."

[A gybe is most easily seen on a small sailboat]

 

 

 

What is "Planing?"

We won't delve into hydrodynamics here any more than we have to. Basically, a boat is restricted in speed by its length. A boat can only move THROUGH the water so fast. Planing is when a boat actually rises ABOVE the water and skims along the surface. Think of a waterskier, or skipping a stone. Traditional monohull sailboats with big keels cannot plane, but many racing boats, dinghies and multihulls can. This is why a boat like an Open 60 can make 25 knots (nautical miles per hour) while a 60 foot cruising boat is stuck at 8 knots.

What is "Surfing?"

Surfing is surfing - like on a surfboard. It is falling down the face of a wave in a controlled way. Even a large, heavy boat can increase its speed dramatically when surfing, and it is one of the most intensely fun things to do on a sailboat - like playing in the waves with a several ton surfboard.

 

What is "Broaching?"

Sailboats rely on the wind for power and the water for leverage. In a multihull, the leverage is provided by the distance between the hulls, and in a monohull, it is provided by the keel (a dinghy uses a centerboard and the sailor's own weight). Broaching generally means when a sailboat is suddenly overpowered, and the wind literally blows the boat over, stopping it in the water. Generally boats round up (steer toward the wind) when they're overpowered, but in certain conditions they will also round down. Rounding up, just like tacking, relieves the pressure from the boat, and is relatively safe in calm sea conditions, but can be very dangerous when in larger waves. Rounding down is also not a good thing, and is generally predicted by difficult rudder control, and a rolling of the boat while sailing downwind. Broaching is never good, and can be disastrous. The lighter the boat, the easier it is to broach.

 

 

 

What is Capsizing?

Capsizing is when a boat flips upside down, and usually refers to the boat flipping sideways or rolling. Most monohulls will roll right back up from a capsize, but some may not, particularly if they have lost their keel. Multihulls simply will not turn back over, and will end up turtling (see below).

 

 

What is Pitchpoling?

Pitchpoling is perhaps the most terrifying event on a sailboat, and is another form of capsizing. Pitchpoling is when a boat capsizes end-over-end, as opposed to rolling. This usually happens when a boat is surfing down the face of a wave too fast. The boat buries its bow at the bottom of the wave (the trough), and then flips over itself, driven by the momentum. It is generally catastrophic when a vessel pitchpoles.

 

 

What is Turtling?

Turtling is when a boat capsizes and can't turn back over (like a turtle - get it?). Multihulls are the most susceptible to this, as without heavy keels or a single, narrow hull, the most stable position for a catamaran or trimaran is upside down. Many multihulls have been built with "turtle hatches" on the underside of the boat, so that crew can escape.

 

What is a Canting Keel?

Generally speaking, a keel is the heavily weighted "fin" at the bottom of a sailboat. Traditionally, this is solidly attached to the hull of the boat, but recent innovations in racing have proven that by putting the keel on a hinge, and moving it from one side to the other - pushing it toward the windward side for more leverage - gives the boat much more speed and control. An added benefit of this is used in designs like the open 60, where the canting keel is actually used to right the boat when it is turtled, and each boat in the Vendee Globe must prove its ability to escape from a turtling with this method.

 

 

What are Running, Reaching, and Polars?

Sailing downwind is "running" with the wind, sailing upwind is "beating" against the wind, usually meaning a boat is "close-hauled" or sailing as close to the wind as possible. In between is called reaching, with a broad reach meaning the boat is almost running, a beam reach meaning that the wind is coming from the side, and a close reach meaning the boat is sailing against the wind. How a boat performs in all of these directions can be expressed in a polar diagram, also known as a boat's "polars." When a skipper is "sailing by the polars" he is trying to get the best performance he can, rather than trying to stick precisely to his course.

 

 

 

What is a "Nautical Mile?"

One minute (one 60th of a degree) in latitude is one nautical mile(nm), or about 1.15 regular (statute) miles. The reason why sailors (and pilots) have used nautical miles instead of any other measurement of distance is that nautical miles represent the curvature of the earth rather than the length of a straight line - something quite important if you believe the Earth to be round. However, because the Earth isn't perfectly round this definition might vary, so the nautical mile is now officially 1,852 meters, exactly.

A "knot" is a measurement of speed, and represents nautical miles per hour.

 

 

What is the "Rhumb Line?"

If you lay out a typical chart (a mercator projection), pick two points, and draw a line between them, that is the rhumb line. It's very easy to navigate using the rhumb line, because you simply take the heading from the chart, and sail in that direction. For most short distances (say, up to a few hundred miles), the rhumb line is perfectly adequate for navigation, and the Earth can be seen as being flat for navigation purposes.

However, the earth is not flat (apologies to the Flat Earth Society), and straight lines aren't generally the shortest distance between two points on a sphere. The shortest distance is what's known as the Great Circle, and on long ocean trips it can make a considerable difference in the distance covered.

 

 

 

What is "the Great Circle?"

The Great Circle is a concept that takes a while to understand, but then you'll never forget it. Now, the sliced orange analogy is overused, but it's a good one. Take a pen, mark two dots on an orange (not on the "equator" or straight up and down from each other on a "meridian" - as these are already "great circles"), and then slice the orange between the two dots with the knife angled toward the very center of the orange. If you were then to remove the peel in one piece and flatten it, what appeared to be a straight line on the orange becomes a curved line on the peel. So, the closest distance between two spots on a sphere is actually plotted as a long curve when using a flat representation - like a chart. Put simply: a mercator chart takes the curve out of the world, and you have to put it back in real life.

The Great Circle is difficult to navigate, as it requires a constant change in direction. If sailing from New York to London, for instance, a Great Circle route starts out as a northeast heading, and ends as a southeast heading. With modern navigation software, the Great Circle is fairly easy to follow, but when navigating by hand, most navigators will choose to break the great circle route up into several rhumb lines approximating the curve.

 

 

 

- Ocean Racing Primer by B. Hampton exclusively for YachtPals.com

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Submitted By YachtPals on 05 Nov

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