Small vs. Tall...

[Breakin Wind]

Seasons Greetings all,

More of a trivia question than anything else, but I had an opportunity while visiting an eastern seaport city this past year, to get relatively close to a larger (if not officially "tall") sailing ship, and I spent more time than my wife could tolerate looking at the rigging and associated parts from the dock trying to figure things out.

I think mostly, it looked like pretty much the same stuff, just bigger and a whole lot more of it.
If anyone knows, is that generally the case? There's a ton of questions that come up, but again generally, are there just a bunch of main sails, and jibs that work together in about the same ways as our single mast boats?

Just curious if anyone knows... Thanks

[GreenLake]

Square rigged sails work quite differently from "our" type of sails, but there are more than similarities in the way the fore-and-aft rigged sails work.

Sails operate in one of two modes, either, like spinnakers, or your mainsail when you sail deep downwind, the sail acts by resisting the flow of air, almost like a flat plate would. Or, like jib and main upwind, they produce lift by having the air stream across the surface.

For the latter, the flow hits the sail where it is attached to forestay or mast, with the former providing an aerodynamically more advantageous configuration (less disturbance of the flow and less drag). For the flow to create lift, it has to remain attached (that is follow the curve of the leeward side of the sail).

When you use the sail in resistance mode, the force is entirely drag, and points in the direction of the wind. If you use the sail to generate lift, there is some drag in the direction of the wind, but the lift is perpendicular to the wind. These two components add up (vector addition) to a total force. That total force can then be broken down into another set of components, one across the boat and one aligned with the center of the boat. As long as the total force is pointing (even a bit) forward, there's a net component that pushes the boat forward.

If you were looking at a big schooner with fore-and-aft rigged sails for example, then all the sails would work like jib and main on the Bermuda rig of the DS. Each sail deflects the wind a bit, so in trimming, the sails would all be trimmed to slightly different angles. Traditional boats have many different kinds of for-and-aft rigged sails, like gaff sails, etc. Their main difference is in the way they are set, and in their aspect ratio.

A gaff sail is not as tall, which makes it aerodynamically less efficient for close upwind work. However, it sits lower, and therefore provides less of a lever arm in heeling the boat, so you can carry perhaps a bit more area - and that area can be useful when you go downwind. You can also drop the gaff without dropping the sail, which "scandalizes" the sail, and works like a quick reef.

So, from a practical point of view, all these different types of sails want to be operated somewhat differently, with a square rigged ship probably being the most different from what you are used to on the DS. If you attempt to establish a flow across the surface of a square-rigged sail, you'll find that the leading edge is unsupported. That makes any close hauled work impossible and you find that ships employing these sails don't go upwind very well (and for the longest time, not at all).

The lines controlling the spar and the sail are also rather different (and more per sail) than what you are used to.

There are many excellent books on the subject of traditional sails and associated sailing techniques. If you are interested, you might start browsing your local library (might need external loan from some regional library) and or online. I've seen many excellent books on this subject at a local second hand bookstore for nautical books, but didn't have the funds to acquire them. Most impressive among them was a detailed book on Chinese Junks, but the price was in the four digits.