Hi
Do you let out/ease a mainsail with a mainsheet on a sailboat? I’m confused about the terminology?
I look forward to your feedback.
Sheets control the trim of the sails. You let out/pull in the main with the mainsheet. Jib sheets control the job and are run outside the stays (the lines or wires run from the mast to the sides of the boat to help stabilize the mast). Rookie move is to feed the jib sheets inside the stays.
You raise/lower the sails with the halyard.
Thanks John Mace. So by let out/easing the main I’m increasing the surface area of the sail. And by doing so am I increasing the speed? What impact does easing the sails have exactly?
Yes. The word “sheet” is confusing. It does not refer to an area of fabric. It refers to a rope used to control a sail. As a good approximation there is only one “rope” on a sail boat. The anchor rope. All others have names. Sheets are known by the sail they control. Mainsail - mainsheet. Jib - jibsheet. However spinnakers have guys, and square rigged boats are mor complex again. On a sailboat “sheet” is also a verb. To “sheet” a sail is to haul on the sheet and cause the sail to set, or to otherwise alter its trim, similarly “sheet on” and “sheet off”.
Nothing to do with area directly. Sails are wings. Sheeting alters the angle of attack. It also changes the overall shape of the sail. It is a bit of a balance, but fortunately you need a flatter sail at the same time as you need a shallow angle of attack.
Raceboats have some curious rules about how many sheets can be used on a sail (one) and where the sheet may be lead to (it must be inside the deck). This leads to compromises in how a sail can be trimmed. Especially for downwind sailing. But, in general you will be trimming a sail to provide an optimal angle of attack to the apparent wind. This provides the greatest lift and thus power. If the wind strength is too heat things become a mess of compromises. A big boat can reduce sail area. Swap to a smaller headsail, reduce the area of the main by “reefing”. Smaller boats can r douce power in the rig by sheeting off slightly or by managing the 3D shape of the sail with other controls. Flattening the sail by applying tension along the luff of themainsail (the edge along the mast) will reduce power. Flexible masts can be controlled to reduce power as well. Eventually sheeting off is all that that is left. Downwind even this doesn’t help.
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Missed the edit window to fix typos. Posted agin. (Posting from iPhone).
Nothing to do with area directly. Sails are wings. Sheeting alters the angle of attack. It also changes the overall shape of the sail. It is a bit of a balance, but fortunately you need a flatter sail at the same time as you need a shallow angle of attack.
Raceboats have some curious rules about how many sheets can be used on a sail (one) and where the sheet may be lead to (it must be inside the deck area). This leads to compromises in how a sail can be trimmed. Especially for downwind sailing. But, in general, you will be trimming a sail to provide an optimal angle of attack to the apparent wind. This provides the greatest lift and thus power. If the wind strength is too great, things become a mess of compromises. A big boat can reduce sail area. Swap to a smaller headsail, reduce the area of the main by “reefing”. Smaller boats can reduce power in the rig by sheeting off slightly or by managing the 3D shape of the sail with other controls. Flattening the sail by applying tension along the luff of the mainsail (the edge along the mast) will reduce power. Flexible masts can be controlled to reduce power as well. Eventually sheeting off is all that that is left. Downwind even this doesn’t help. Just sheeting off does not always produce the best way of depowering as you want to get rid of the power high up in the rig and keep it down lower. Power up high has the additional height of the mast to provide heeling moment.
Thanks Francis Vaughan. Terrific explanation!
I’ll add the other complication to make at least the second round of compromises pretty much complete. Sails twist. The tension in the leech (the vertical edge of the sail that isn’t fixed - either to the mast or to the forestay) controls how much the sail twists. The more tension, the less it twists. Twist is important. The speed of the wind increases with height above the water (in principle touching the water the speed is zero, and it increases from there.) This means that the angle of attack the wind makes with the sail changes with height. The apparent angle depends thus on a mix of - the boat’s angle to the true wind, the boat’s, current speed, and the height above the sea. In order to cope with the latter a sail is allowed to twist. Or not. It depends upon what the best angle is. The angle the sheet forces makes with the sail will control both the overall sheeting angle and the tension in the leech, thus controlling the twist in the sail. Jib sheets will often have moveable “fairleads” - the device which turns the sheet where it first meets the deck, and main-sheets often have a moveable sheeting system on a track (called a traveller) that allows the sheeting angle to be adjusted reasonably indepently of the leech tension. This results in a system where sheeting angle is predominantly controlled by traveller, and leech tension is predominantly controlled by main-sheet tension. Modern sails have evolved to the point where very high sheet loads are common - in order to control twist. Sails may be made of composite fabrics, often involving carbon fibre, kevlar, spectra and the like. They can take insane loads, and can be made to follow very precise forms. Advanced forms of these sails are actually moulded in the right shape, lesser sails have the shape created by stitching together panels with precise shapes. The stresses in the sail are controlled with precise layout of the direction of the fabric threads. Many modern boat designs have moved to a square topped mainsail. These often require very high sheet loads to control the shape of.
In the 33rd America’s cup the difference between a solid wing and a soft sail was very apparent. Because a solid wing has a defined shape, control of twist is accomplished easily by segmenting the wing. It does not rely upon tension along the leech. Alinghi’s soft sail had ridiculous loads on it, whilst Oracle’s wing could be trimmed with about one tenth the forces.
Finally, in a Bermudan rigged (ie jib and mainsail) sailboat, the jib and mainsail work as a single wing. It is essentially a wing with a leading edge slot. Control of the airflow in the slot (the gap between the jib and the mainsail) is critical and thus the precise sheeting of the jib makes a bigger difference that you would expect. Again, twist is important, and this controls the slot shape along the length of the mast. It controls the angle of attack seen by the mainsail, and in particular is critical in avoiding flow detachment. Precise location of the jib fairlead is critical here.
Thanks Francis Vaughan. Do you know of any autobiographies or perhaps good works of fiction that give an accurate and fairly comprehensive account of modern sailing? I know there are plenty of manuals on the market, but I’m looking for real experiences and how these 'by the book" sailing procedures play out in real life.
What do you define as modern?
20th century to recent times. As long as it includes modern sailing terminology/jargon, I’m happy.
Sir Robin Knox Johnson comes to mind immediately. He is something of a sailing god and has written of his efforts. Eric Tarbaly would have been good, there is a nice movie of his life, but he was lost too young, and didn’t write.
Thanks Francis Vaughan. I’ll look them up immediately. Much appreciated!
I’m skeptical that this is in common use. The term “anchor rode” certainly is, as is “anchor line”.
Other “ropes” aboard a sailing vessel are bolt ropes (sewn around the edge of a sail), manropes (flexible handholds / railings) and bell ropes (pull to ring the bell).
You are probably right. I forgot about bolt rope. Pedantically the anchor rode is the whole cabooble, rope and chain. I was really trying to make a point that every rope or line has a name. Those names can be less than obvious.
Sailors rarely use the term “rope” when referring to sheets or halyards an such. They would normally use the generic term “line”.
Up to a point. You also get many “hauls” In-haul, out-haul, up-haul, down-haul. Collectively these are all control lines. Sheets are never called anything but sheets, and halyards are never called anything but halyards. They can be made of rope, but are never called ropes. That perhaps is the critical issue. You can have coils of rope awaiting use, but the moment the rope is actually put to use, it becomes the named entity, and no longer “rope”.
An interesting thing I just learned: “know the ropes” is certainly used aboard ship, but may not have a nautical origin - it may have originated in the theater. It’s first attested in R.H. Dana’s Two Years Before the Mast, where it appears in quotes (as if it’s a well-known expression).
Yep. “Trim that there rope over there” would get you laughed at if you issued that as a command on a sailboat. I grew up around sailboats, and much of the first class I took was focused on nomenclature. It’s a whole different world of words once you step on that boat!
Fore, aft, starboard, port, lee, windward, weather, fall off, head up, tack, jibe, tiller, centerboard, keel, telltale… the list goes on and on.
Yes do get the correct terms down. Boat people get QUITE upset when I say things like “The pointy end of the boat”, etc.